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Learning about heat and temperature : a study of a grade nine science class Haggerty, Sharon May 1986

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LEARNING ABOUT HEAT AND TEMPERATURE: A STUDY OF A GRADE NINE SCIENCE CLASS by SHARON MAY HAGGERTY B . A . , U n i v e r s i t y of Saskatchewan, 1961 M . S . , U n i v e r s i t y of M i n n e s o t a , 1968 B . E d . , U n i v e r s i t y of R e g i n a , 1971 M . E d . , U n i v e r s i t y of R e g i n a , 1978 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF EDUCATION i n THE FACULTY OF GRADUATE STUDIES Department of Mathemat ics and S c i e n c e E d u c a t i o n We accept t h i s t h e s i s as c o n f o r m i n g to the r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA March 1986 © Sharon May H a g g e r t y , 1986 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Sharon M. Haggerty Department of Mathematics and Sdp.nr.e Education The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date March 27. 1986  DE-6(3/81) i i ABSTRACT Many students complete science units with l i t t l e or no understanding of the concepts taught. Such students frequently cope with d i f f i c u l t science concepts by memorizing d e f i n i t i o n s , formulas and other school science facts. Some researchers have suggested that one factor which may be related to d i f f i c u l t i e s students have i s the students' prior b e l i e f s about the topic. If a student possesses well established b e l i e f s about s c i e n t i f i c phenomena, and i f those b e l i e f s are contrary to the view presented in school science, the student is placed in a c o n f l i c t p o s i t i o n . If instruction does nothing to d i s c r e d i t a prior a l t e r n a t i v e b e l i e f , a student may reject the school science view, in favour of his/her alternative view. Students' b e l i e f s about heat and temperature were investigated prior to, and during a grade nine science unit. Many of the students' prior alternative b e l i e f s persisted in spite of ins t r u c t i o n . Instruction did not attempt to d i s c r e d i t the alternative b e l i e f s . Rather, the school science view was presented and said to be correct. Many students responded by memorizing school science d e f i n i t i o n s and facts. Some students appeared to distinguish between correct answers for school science and what they believed to be true, giving one view on the school science test and another on the posttest. School science achievement was s i g n i f i c a n t l y related to success on the lowest l e v e l questions of the posttest, but not to higher l e v e l questions, presumably because many students r e l i e d on rote learning for their success in school science. Boys outperformed g i r l s on higher l e v e l , but not lower l e v e l posttest questions. Boys contributed more to class discussion than did g i r l s , and p a r t i c i p a t i o n in class discussion was related to success on higher l e v e l posttest questions. Five factors appeared to account, in part, for many of the d i f f i c u l t i e s experienced by students: many phenomena were explained in terms of the mechanical energy of the p a r t i c l e s of matter; some phenomena were not explained, and some of the more competent students expected to have explanations; some alte r n a t i v e b e l i e f s were neither i d e n t i f i e d nor addressed during i n s t r u c t i o n ; many students seemed unaware of the function of a s c i e n t i f i c model; and, some concepts were not adequately discussed in c l a s s . iv TABLE OF CONTENTS ABSTRACT i i LIST OF TABLES X LIST OF FIGURES xi ACKNOWLEDGEMENTS x i i Chapter I: The Problem 1.0. Introduction 1 1.1. Science Concepts and Learning and Development .. 3 1.2. The Concepts of Heat and Temperature 4 1.3. Sex Differences in Learning Science 7 1.4. Junior Secondary Science 8 1.5. Problem Statement 10 1.6. Delimitation of the Study 11 1.7. Summary 12 1.8. Def i n i t i o n s 12 Chapter I I : Review of the Literature 2.0. Introduction 16 2.1. Factors Influencing How Children Learn Science . 16 2.1.1. Prior B e l i e f s and Instruction 17 2.1.2. The Influence of Gender 24 2.2. Children's B e l i e f s About Heat and Temperature .. 27 2.3. Investigating the Learning of Science Concepts in the Classroom 30 2.4. Summary 33 V Chapter I I I : Methods 3.0. I n t r o d u c t i o n 35 3.1. Phase I 37 3.1.1. The P r e t e s t 38 3.1.2. S e l e c t i o n of Target Students 41 3.1.3. Target Student Interview 42 3.1.4. Cur r i c u l u m and Textbook A n a l y s i s 43 3.1.5. Summary 43 3.2. Phase II 44 3.2.1. Lea r n i n g : How Does the Student Respond to I n s t r u c t i o n and I n s t r u c t i o n a l M a t e r i a l s ? 47 3.2.2. I n s t r u c t i o n : How Does the Teacher Provide f o r Learning? 48 3.3. Phase III 49 3.4. Summary - 50 Chapter IV: P e r s p e c t i v e s of Heat and Temperature 4.0. I n t r o d u c t i o n 52 4.1. A n a l y s i n g the Data 55 4.1.1. S c i e n t i s t s ' Science 55 4.1.2. School Science 56 4.1.3. C h i l d r e n ' s Science 56 4.2. The S c i e n t i s t s ' P e r s p e c t i v e : S c i e n t i s t s ' Science 58 4.3. The Curriculum P e r s p e c t i v e : School Science 59 4.3.1. Goals and O b j e c t i v e s of the Unit 60 4.3.2. The Content of the Unit 63 v i 4.3.3. Teaching the Un i t 69 4.4. The Students' P e r s p e c t i v e : C h i l d r e n ' s Science .. 70 4.4.1. D i s t i n c t i o n s Which Led to Student D i f f i c u l t i e s 71 4.4.2. Students' Ideas and B e l i e f s 73 4.5. Summary 107 Chapter V: C h i l d r e n ' s S c i e n c e : L e a r n i n g 5.0. I n t r o d u c t i o n 110 5.1. A n a l y s i s of Data 113 5.1.1. Q u a l i t a t i v e A n a l y s i s 113 5.1.2. Q u a n t i t a t i v e A n a l y s i s 113 5.2. L e a r n i n g : Measures of Success 116 5.2.1. Lea r n i n g : Success i n School Science 118 5.2.2. L e a r n i n g : Success on the P o s t t e s t 121 5.2.3. L e a r n i n g : Gains i n Scores From the P r e t e s t to the P o s t t e s t 122 5.2.4. Summary 124 5.3. C h a r a c t e r i s t i c s of S u c c e s s f u l Learners 125 5.3.1. Learning and P a r t i c i p a t i o n i n C l a s s Dialogue 126 5.3.2. Learning and Gender 127 5.3.3. Learning and the Target Students 134 5.3.4. Summary 137 5.4. Lack of Success i n L e a r n i n g : P e r s i s t a n t A l t e r n a t i v e B e l i e f s 137 5.4.1. The Thermal Expansion of Matter at the P a r t i c l e L e v e l 138 v i i 5.4.2. The Nature and Extent of the Spaces Between the P a r t i c l e s of Matter 144 5.4.3. The Nature of Heat and the Difference Between Heat and Temperature 144 5.4.4. The Type of Material as a Factor Related to the Heat Energy ( i . e . , Internal Energy) of Matter 147 5.4.5. When Matter i s Heated, the Rate of Temperature Change i s Not Constant When a Change of Phase Occurs 150 5.4.6. The Nature of Cold and the Difference Between Heat and Cold 153 5.4.7. The Effects of Heating on Different Kinds of Matter 155 5.4.8. How Conduction Occurs at the P a r t i c l e Level '. 157 5.4.9. The Effe c t of the Type of Material on the Rate at Which Heat i s Transferred by Conduction 158 5.4.10. How Heat is Transferred by Radiation ... 159 5.5. Summary 160 Chapter VI: School Science: Instruction 6.0. Introduction 162 6.1. Analysis of the Data 164 6.2. The Teacher as Instructional Manager 166 6.3. The Roles of the Teacher During Class Discussion 172 v i i i 6.3.1. The Teacher as Evaluator of Student Knowledge, Ideas and B e l i e f s 173 6.3.2. The Teacher as Provider or Interpreter of Science Knowledge 176 6.3.3. The Teacher as Mediator of Discrepancies Between School Science and Children's Science 180 6.4. Instruction and Alternative B e l i e f s 188 6.4.1. School Science Attempts to Explain Heat Phenomena in Terms of Mechanical Energy .... 191 6.4.2. The S c i e n t i s t s ' Science Explanation of a Phenomenon Was Omitted 192 6.4.3. Alternative B e l i e f s Were Not Id e n t i f i e d . 194 6.4.4. Confusion About the Use of S c i e n t i f i c Models 195 6.4.5. The Teacher's Explanation Was Not Understood by the Students 197 6.5. Summary 197 Chapter VII: Conclusions and Recommendations 7.0. Overview of the Study 202 7.0.1. Rationale 202 7.0.2. Summary 202 7.1. Conclusions 204 7.1.1. School Science 204 7.1.2. S c i e n t i s t s ' Science and School Science .. 208 ix 7.1.3. Children's Science: Belie f s About Heat and Temperature and the Particulate Nature of Matter 208 7.1.4. Learning and Instruction 209 7.2. Recommendations 214 ^7^.2.1. Teaching School Science 214 7.2.2. Research . — 216 REFERENCE NOTES 217 REFERENCES 218 APPENDIX A: Pretest/Posttest: Heat and Temperature 224 APPENDIX B: Protocol for Student Interview 233 APPENDIX C: Heat and Temperature Unit Test 239 APPENDIX D: Conceptual Biography: Jane 241 APPENDIX E: The Phase Change Investigation (Inv. 1.45) .... 246 X LIST OF TABLES Table 2.1. Summaries of Conceptions of Heat and Temperature 29 Table 2.2. Summary of the Kinetic Framework 30 Table 4.1. Ess e n t i a l Learning Outcomes, Grade Nine Science (1979) 61 Table 4.2. Optional Learning Outcomes, Grade Nine Science (1979) 62 Table 4.3. Contents of Chapters 7, 8 and 9 64 Table 5.1. Test Scores for' Three Selected Target Students. 111 Table 5.2. Range of Scores: Pretest and Posttest 114 Table 5.3. Students' Posttest Scores and School Science Marks 119 Table 5.4. Correlation Matrix 120 Table 5.5. Analysis of Covariance: Posttest by Talk with Pretest 128 Table 5.6. Results of the B r i t i s h Columbia Ministry Grade 12 Science Examinations, January, 1985 129 Table 5.7. Tabulation of Student-Teacher Dialogue, by Gender, During 160 Minutes of Class Discussion .... 131 Table 5.8. Analysis of Covariance: Posttest by Gender with Pretest 133 Table 5.9. Analysis of Variance: Posttest by Gender and Talk 136 Table 6.1. Class A c t i v i t i e s and Assignments 171 Table.6.2. Student-Teacher Dialogue 175 LIST OF FIGURES xi Figure 5.1. Posttest Scores as a Function of Talk, by Gender 135 x i i ACKNOWLEDGEMENTS I would l i k e to express my sincere thanks to the members of my supervisory committee, Drs. G.L. Erickson, P.J. Gaskell, P.K. A r l i n , and P.W. Matthews for their encouragement and guidance throughout the study, and to the science teacher who so agreeably tolerated my probing presence in her science class for two months. The Haggerty family assisted in many ways, and I p a r t i c u l a r l y thank Irene, Michael, Brenda, Megan and John for ensuring that I had the time needed to complete such a lengthy task. Financial assistance for the study was provided through a scholarship from The Delta Kappa Gamma Society International, and a Discretionary Grant from the Educational Research Institute of B r i t i s h Columbia, both of which are g r a t e f u l l y ac knowledged. 1 CHAPTER I INTRODUCTION 1.0. I n t r o d u c t i o n Assessments of sc i e n c e knowledge conducted i n B r i t i s h Columbia ( T a y l o r , 1982; and Hobbs, B o l d t , E r i c k s o n , Quelch and Sieben, 1979), the Un i t e d S t a t e s (NAEP, 1978) and i n t e r n a t i o n a l l y (Comber and Keeves, 1973) have r e v e a l e d s t a r t l i n g misunderstandings about many of the b a s i c s c i e n c e concepts. The 1978 B r i t i s h Columbia assessment team concluded "apparently many students leave school with l i m i t e d understanding of some very fundamental concepts" (Hobbs et a l . , 1979, p. 94). The Science C o u n c i l of Canada has a l s o expressed concern about school s c i e n c e e d u c a t i o n . In 1980 a l a r g e s c a l e i n v e s t i g a t i o n was launched, aimed at a n a l y s i n g the h i s t o r y of Canadian s c i e n c e e d u c a t i o n , i t s present purposes and c h a r a c t e r i s t i c s , and promoting " a c t i v e d e l i b e r a t i o n concerning f u t u r e o p t i o n s f o r sc i e n c e education i n Canada" (Orpwood, 1980). The Science C o u n c i l f i n a l r e p o r t (1984) p r o v i d e d a comprehensive d e s c r i p t i o n of Canadian school s c i e n c e and i d e n t i f i e d a number of q u e s t i o n s which the authors f e l t need to be addressed. Thus we f i n d not only are education o f f i c i a l s and res e a r c h e r s u r g i n g i n q u i r y i n t o the t e a c h i n g of s c i e n c e , but there i s concern w i t h i n the s c i e n t i f i c community as w e l l . - S e v e r a l s t u d i e s conducted at the U n i v e r s i t y of B r i t i s h Columbia and elsewhere ( A g u i r r e , 1981; Anamuah-Mensah, 1981; 2 Arnaudin and Mintzes, 1985; Deadman and K e l l y , 1978; E r i c k s o n , 1975, 1979, 1980; and Novick and Nussbaum, 1981, among others) have e x p l o r e d c h i l d r e n ' s ideas about a v a r i e t y of s c i e n c e concepts, mostly i n c l i n i c a l s e t t i n g s . B e l i e f s which are at va r i a n c e with the accepted s c i e n t i f i c view are sometimes r e f e r r e d to as " a l t e r n a t i ve b e l i e f s " ( D r i v e r , 1981). The term " a l t e r n a t i v e framework" may be used to d e s c r i b e an i n t e g r a t e d set of ideas or b e l i e f s which d i f f e r s from the c u r r e n t s c i e n t i f i c view. As Posner, S t r i k e , Hewson and Gertzog (1982, p. 211) have i n d i c a t e d , " i d e n t i f y i n g ' a l t e r n a t i v e frameworks,' and understanding some reasons f o r t h e i r p e r s i s t e n c e , f a l l s short of developing a reasonable view of how a student's c u r r e n t ideas i n t e r a c t with new, incompatible i d e a s . " The present study addressed t h i s l a t t e r problem, i n v e s t i g a t i n g the i n t e r a c t i o n between students' p r i o r knowledge and i n s t r u c t i o n . The study was conducted i n a n a t u r a l classroom s e t t i n g , as a grade nine c l a s s s t u d i e d a u n i t on heat and temperature. The t o p i c of heat and temperature was s e l e c t e d f o r two reasons. F i r s t , c h i l d r e n ' s ideas about heat and temperature have been p r e v i o u s l y i n v e s t i g a t e d and are well known ( E r i c k s o n , 1975, 1979, 1980; and Shayer and Wylam, 1981). Secondly, heat and temperature i s a t o p i c which i s c o n s i s t e n t l y taught at the j u n i o r secondary l e v e l a c r o s s Canada (Connelly, Crocker and Kass, 1984) and which poses many d i f f i c u l t i e s f o r students. 3 1.1. Science Concepts and L e a r n i n g and Development Much of the recent r e s e a r c h i n t o l e a r n i n g of s c i e n c e has r e v o l v e d around c h i l d r e n ' s a b i l i t i e s , or lack t h e r e o f , to demonstrate the c a p a c i t y f o r "formal reasoning," as d e f i n e d by P i a g e t i a n theory. Formal reasoning a b i l i t i e s • i n c l u d e p r o p o r t i o n a l i t y , h y p o t h e t i c o - d e d u c t i v e reasoning, c o n t r o l l i n g v a r i a b l e s and p r o p o s i t i o n a l l o g i c , among o t h e r s . These a b i l i t i e s are c o n s i d e r e d by many r e s e a r c h e r s to be b a s i c to an understanding of most sci e n c e concepts s t u d i e d at the secondary l e v e l (e.g., Lawson, 1983, 1985; Shayer and Wylam, 1981). T h i s r e s e a r c h may underestimate the i n f l u e n c e on l e a r n i n g of what c h i l d r e n a l r e a d y know about a concept, i r r e s p e c t i v e df P i a g e t i a n stage. Another approach to i n v e s t i g a t i n g l e a r n i n g i n s c i e n c e has been based on the knowledge c h i l d r e n b r i n g to the classroom. T h i s approach i s o f t e n a s s o c i a t e d with Ausubel's concept of " p r i o r c o g n i t i v e s t r u c t u r e s . " Novak (1977), i n a summary of Ausubel's theory, s t a t e d that the most important idea i n that theory was simply that the "most important s i n g l e f a c t o r i n f l u e n c i n g l e a r n i n g i s what the l e a r n e r a l r e a d y knows." The importance of c h i l d r e n ' s ideas about s c i e n c e concepts i s becoming more widely recognized as a f r u i t f u l area of r e s e a r c h . S t u d i e s have shown that many c h i l d r e n have i n f o r m a l l y developed b e l i e f s about c e r t a i n s c i e n t i f i c phenomena, and that many of these b e l i e f s are based upon a p e r s p e c t i v e d i f f e r e n t from that of the c u r r e n t s c i e n t i f i c d i s c i p l i n e . T h i s incongruency may subsequently r e s u l t , as Hawkins (1978) has suggested, in " c r i t i c a l b a r r i e r s " which act to i n t e r f e r e with 4 the c h i l d ' s l e a r n i n g . D r i v e r and E a s l e y (1978) r e f e r to s e t s of these ideas as " a l t e r n a t i v e frameworks," while Hewson and Hewson (1983) use the term " a l t e r n a t i v e c o n c e p t i o n s . " L i t t l e i s known about the e f f e c t of a l t e r n a t i v e b e l i e f s on a c h i l d ' s c a p a c i t y to l e a r n the s c i e n t i f i c a l l y accepted view of concepts. Teachers and c u r r i c u l u m developers appear to assume that p r e s e n t i n g evidence of the accepted view w i l l r e s u l t i n the students' embracing that view. Recent s t u d i e s (e.g., Hewson and Hewson, 1983; Osborne and W i t t r o c k , 1983; and Pope and G i l b e r t , 1983) suggest that t h i s assumption i s o f t e n not warranted. In t h i s study, the l e a r n e r s ' p r i o r b e l i e f s about heat and temperature were f i r s t i d e n t i f i e d , and then the extent to which those a l t e r n a t i v e b e l i e f s were r e p l a c e d by s c i e n t i f i c ideas was i n v e s t i g a t e d i n t h i s study. F i n a l l y , f a c t o r s which may be r e l a t e d to the p e r s i s t e n c e of, or changes in student b e l i e f s were ex p l o r e d . 1.2. The Concepts of Heat and Temperature • One of the f i r s t words lear n e d by many c h i l d r e n i s "hot." I n i t i a l l y "hot" and " c o l d " are i n d i s t i n g u i s h a b l e , evidenced by the t o d d l e r who exclaims "hot!" a f t e r h i s f i r s t t a s t e of i c e cream. Soon the young c h i l d l e a r n s to d i s t i n g u i s h hot and c o l d , but an understanding of the d i s t i n c t i o n between heat and temperature may never be e s t a b l i s h e d . The development of the concepts of heat and temperature in school-age c h i l d r e n has been s t u d i e d by s e v e r a l i n v e s t i g a t o r s ( A l b e r t , 1974, 1978; E r i c k s o n , 1975, 1979, 1980; Hewson and Hamlyn, 1984; Shayer and Wylam, 1981; Stavy and Berkowitz, 1980; T i b e r g h i e n , 1980 and T r i p l e t t , 5 1973). As a r e s u l t of these s t u d i e s , c h i l d r e n ' s a l t e r n a t i v e b e l i e f s about heat and temperature are r e l a t i v e l y w e l l known. The impact of those b e l i e f s on l e a r n i n g and t h e i r i n t e r a c t i o n with that l e a r n i n g , has not been i n v e s t i g a t e d . A study of f o u r t h grade c h i l d r e n in I s r a e l (Stavy and Berkowitz, 1980) re v e a l e d that completion of a u n i t on temperature d i d not r e s u l t i n the c h i l d r e n modifying the ideas they h e l d p r i o r to i n s t r u c t i o n . The c h i l d r e n measured the temperature of water i n two c o n t a i n e r s and found each to be 10°C. When the water from the two c o n t a i n e r s was combined, many c h i l d r e n expected the mixture, to have a temperature of 20°C (10 + 10 = 20). When the r e s u l t i n g temperature was found to be 10°C, many c h i l d r e n concluded there was something wrong with the thermometer. They were unable to a s s i m i l a t e the unexpected r e s u l t , although the same c h i l d r e n had p r e v i o u s l y recognized that c o l d water combined with c o l d water r e s u l t e d i n c o l d water. In t h i s case, the c h i l d r e n ' s a l t e r n a t i v e b e l i e f appears to have l e d them to r e j e c t t h e i r experimental f i n d i n g s . Although temperature i s d i s c u s s e d d a i l y by almost everyone, the d i s t i n c t i o n between heat and temperature i s not w e l l understood. Many a d u l t s cannot e x p l a i n the d i f f e r e n c e . While temperature i s r e a d i l y measured, heat cannot be measured d i r e c t l y , and t h i s i s undoubtedly much of the problem. In the grade nine s c i e n c e textbook (Schmid and Murphy, 1979) heat i s d e f i n e d as the t o t a l mechanical energy of a l l the p a r t i c l e s added up. Temperature i s s a i d to depend on the average mechanical energy of each p a r t i c l e . In these school s c i e n c e d e f i n i t i o n s , " p a r t i c l e s " r e f e r to atoms and molecules. 6 In thermodynamics, the former d e f i n i t i o n would more a c c u r a t e l y d e s c r i b e " i n t e r n a l energy," with the term "heat" being r e s t r i c t e d to energy which i s i n motion a c r o s s a temperature g r a d i e n t . T h i s d i s t i n c t i o n has not been made f o r students at t h i s grade l e v e l . Thus we f i n d terms being used d i f f e r e n t l y in d i f f e r e n t c o n t e x t s . In t h i s study we w i l l r e f e r to concepts and d e f i n i t i o n s drawn from the f i e l d of thermodynamics as " s c i e n t i s t s ' s c i e n c e . " The concepts and d e f i n i t i o n s presented i n the grade nine s c i e n c e program w i l l be r e f e r r e d to as "school s c i e n c e . " An a d d i t i o n a l category, " c h i l d r e n ' s s c i e n c e , " w i l l r e f e r to the students' ideas and b e l i e f s about heat and temperature concepts. Summers (1983) has recog n i z e d the d i f f i c u l t i e s students have with the concept of heat, and has proposed that the word "heat" should not be used as a noun at a l l . He suggested the f o l l o w i n g terminology: "heating i s the name given to the process by which i n t e r n a l energy t r a n s f e r s occur as a r e s u l t of a temperature d i f f e r e n c e . " In t h i s study however, we w i l l c o n s i d e r the terms "heat" and "heat energy" i n the school s c i e n c e sense, to i n c l u d e the concept of i n t e r n a l energy. A number of scie n c e concepts are i n v o l v e d i n an understanding of heat and temperature. B a s i c to that understanding are the k i n e t i c theory of matter ( s t u d i e d i n the B r i t i s h Columbia grade e i g h t s c i e n c e course) and the law of co n s e r v a t i o n of ' energy ( s t u d i e d i n the grade nine course, immediately before the study of heat energy). To s a t i s f a c t o r i l y complete the heat and temperature u n i t , students must understand the r e l a t i o n s h i p between p a r t i c l e motion and heat energy, and be 7 a b l e to e x p l a i n the phenomena of thermal expansion, conduction, c o n v e c t i o n , r a d i a t i o n , temperature, phase changes and i n s u l a t i o n i n terms of those r e l a t i o n s h i p s . None of the p r e v i o u s s t u d i e s of c h i l d r e n ' s b e l i e f s about heat and temperature have examined the i n t e r a c t i o n of the a l t e r n a t i v e b e l i e f s h e l d by students and the development of heat and temperature concepts d u r i n g i n s t r u c t i o n i n an a c t u a l classroom s e t t i n g . T h i s study has i n v e s t i g a t e d that i n t e r a c t i o n . 1.3. Sex D i f f e r e n c e s i n L e a r n i n g Science Sex d i f f e r e n c e s i n achievement have been r e p o r t e d i n the s c i e n c e assessments r e f e r r e d to e a r l i e r . In the B r i t i s h Columbia assessments, as i n o t h e r s , sex d i f f e r e n c e s were g r e a t e s t on p h y s i c s q u e s t i o n s and at higher grade l e v e l s . P h y s i c s concept and a p p l i c a t i o n q u e s t i o n s were p a r t i c u l a r l y d i f f i c u l t f o r g i r l s . A c l o s e r look at items r e l a t e d to heat and temperature r e v e a l s some i n t e r e s t i n g v a r i a t i o n s i n responses given by males and females (Hobbs et a l . , 1979). The number of c o r r e c t responses to items whose content was k i t c h e n - r e l a t e d ( l o o s e n i n g jam j a r l i d s by h e a t i n g the l i d and how a r e f r i g e r a t o r keeps food c o o l ) d i d not d i f f e r g r e a t l y between males and females. However, items r e l a t e d to l a b o r a t o r y a c t i v i t i e s d i d e l i c i t d i f f e r e n t responses. For example, on the 1978 grade e i g h t t e s t , 54 percent of the males and only 40 percent of the females had c o r r e c t responses on an item concerning the f i n a l temperature of water when two equal volumes i n i t i a l l y at d i f f e r e n t temperatures are combined. Another item 8 asked why the stopper popped out when a stoppered t e s t - t u b e of water was heated. On t h i s item the responses were 63 and 47 percent c o r r e c t f o r males and females r e s p e c t i v e l y . S i m i l a r d i f f e r e n c e s were observed i n 1982 ( T a y l o r , 1982). On a q u e s t i o n as k i n g f o r the f i n a l temperature i f one l i t r e of water at 50°C were combined with one l i t r e of water at 70°C, 53 percent of the males and 34 percent of the females c o r r e c t l y p r e d i c t e d 60°. The g i r l s were even l e s s s u c c e s s f u l than i n 1978. T h i r t y - t h r e e percent of the students ( u n f o r t u n a t e l y the r e p o r t d i d not i n d i c a t e percentages of males and females f o r i n c o r r e c t responses) chose 120° as t h e i r answer. Reasons f o r such sex d i f f e r e n c e s are not c l e a r . These r e s u l t s would suggest that the context of a q u e s t i o n has an e f f e c t on success r a t e s , but t h i s has not been documented. Two a s p e c t s of t h i s phenomenon were i n v e s t i g a t e d . Sex of the student was c o n s i d e r e d i n r e l a t i o n to student understanding of heat and temperature p r i o r to and upon completion of the heat and temperature u n i t . In a d d i t i o n , classroom o b s e r v a t i o n s i n v e s t i g a t e d d i f f e r e n t i a l treatment and responses of boys and g i r l s d u r i n g i n s t r u c t i o n . 1.4. J u n i o r Secondary Science The d e c i s i o n to examine j u n i o r secondary s c i e n c e was based on the g e n e r a l concern that has been expressed about s c i e n c e education at t h i s l e v e l and the apparent d e c l i n e i n a t t i t u d e s towards s c i e n c e that occurs d u r i n g the j u n i o r secondary years. The f i r s t B r i t i s h Columbia s c i e n c e assessment (Hobbs et a l . , 1979) i d e n t i f i e d the j u n i o r secondary l e v e l as the area of 9 g r e a t e s t concern at that time. S e v e r a l reasons were given to support that view. The I n t e r p r e t a t i o n Panel judged that performance was l e s s than s a t i s f a c t o r y f o r 70 percent of the items on the grade 12 achievement t e s t , compared to 30 and 18 percent r e s p e c t i v e l y f o r grades e i g h t and f o u r . Of 26,416 grade 12 students surveyed i n 1978, 36 percent had not completed any s e n i o r secondary s c i e n c e courses. These data i n d i c a t e a s u b s t a n t i a l p o r t i o n of students take no s c i e n c e beyond the j u n i o r secondary l e v e l . U n f o r t u n a t e l y , comparable data were not p r o v i d e d i n the second assessment. The Science C o u n c i l of Canada (1984) r e p o r t e d that only Manitoba r e q u i r e d a grade 11 s c i e n c e course f o r high school graduation ( B r i t i s h Columbia i s about to implement a s c i e n c e 11 requirement).and recommended that a l l p r o v i n c e s should r e q u i r e s c i e n c e every year to grade 11 as a graduation requirement. S t u d i e s i n the U n i t e d States have a l s o expressed concerns about j u n i o r secondary s c i e n c e . Buccino and Evans (1981) found that most students r e c e i v e a l l of t h e i r high school s c i e n c e i n s t r u c t i o n at the j u n i o r high l e v e l . Recent s t u d i e s i n B r i t i s h Columbia (Duncan and Haggerty, 1985) and North C a r o l i n a (Simpson and O l i v e r , 1985), and the American N a t i o n a l Assessment of E d u c a t i o n a l Progress (Yager and Yager, 1985) have a l l r e p o r t e d a steady d e c l i n e i n a t t i t u d e s towards s c i e n c e as students progress through the j u n i o r secondary years. Thus, there appears to be widespread consensus on the need f o r a c l o s e r look at the t e a c h i n g of s c i e n c e at t h i s l e v e l . 10 1.5. Problem Statement The general aim of the c u r r e n t study was to i n v e s t i g a t e ways students' p r i o r b e l i e f s about matter, heat and temperature i n f l u e n c e d t h e i r understanding of the concepts of heat and temperature as presented d u r i n g an i n s t r u c t i o n a l u n i t . In p a r t i c u l a r , e i g h t q u e s t i o n s were addressed. The f i r s t two q u e s t i o n s look at school s c i e n c e - - t h e concepts as they are presented to the students. 1. How are the concepts of heat and temperature presented to grade nine students i n school s c i e n c e ( i . e . , by the c u r r i c u l u m , the textbook and the te a c h e r ) ? 2. Does school s c i e n c e d i f f e r from s c i e n t i s t s ' s c i e n c e ? If so, i n what ways? The next two q u e s t i o n s examine c h i l d r e n ' s s c i e n c e p r i o r to and upon completion of the heat and temperature u n i t . 3. What are students' ideas about matter, heat and temperature p r i o r to studying a sc i e n c e u n i t on heat and temperature? 4. To what extent do student b e l i e f s about matter, heat and temperature change a f t e r completing a u n i t on heat and temperature? The next q u e s t i o n looks at the l e a r n e r s as they proceeded through the u n i t . 5. What c h a r a c t e r i s t i c s d i s t i n g u i s h the more s u c c e s s f u l from the l e s s s u c c e s s f u l l e a r n e r ? In p a r t i c u l a r , are there d i f f e r e n c e s i n l e a r n i n g that are r e l a t e d to gender? Two q u e s t i o n s address the i n s t r u c t i o n that was p r o v i d e d . The emphasis i s on the i n t e r a c t i o n between the teacher and the students i n the c l a s s . 11 6. How does the teacher provide o p p o r t u n i t i e s f o r students to l e a r n about heat and temperature? 7. How does the teacher respond when a l t e r n a t i v e b e l i e f s are expressed by students? The l a s t q u e s t i o n addressed the key goal of the study. 8. I f some a l t e r n a t i v e b e l i e f s p e r s i s t i n s p i t e of that i n s t r u c t i o n , what are some p o s s i b l e e x p l a n a t i o n s f o r that p e r s i s t e n c e ? 1.6. D e l i m i t a t i o n of the Study As s t a t e d e a r l i e r , t h i s study has examined a l t e r n a t i v e b e l i e f s about heat and temperature h e l d by j u n i o r secondary students, and has i n v e s t i g a t e d the i n t e r a c t i o n of these b e l i e f s with the l e a r n i n g of concepts presented d u r i n g the study of heat and temperature i n a grade nine s c i e n c e c l a s s . The study i n v e s t i g a t e d one B r i t i s h Columbia lower mainland grade nine s c i e n c e c l a s s . The f i n d i n g s can only be regarded as t e n t a t i v e , given the l i m i t e d nature of the data base. Many concerns have been i d e n t i f i e d and w i l l provide o p p o r t u n i t i e s f o r f u r t h e r i n v e s t i g a t i o n . The reader must examine the f i n d i n g s , and then, based on the d e s c r i p t i o n of the c l a s s i n v e s t i g a t e d , he/she w i l l be able to judge the extent to which these f i n d i n g s are compatible with h i s / h e r own te a c h i n g experience and/or s i t u a t i o n . 1 2 1.7. Summary This chapter has summarized the rationale behind the study. Widespread concern about students' understanding of science concepts has been i d e n t i f i e d and i t has been suggested that children's p r i o r , alternative b e l i e f s about science may be related to d i f f i c u l t i e s students have acquiring these concepts. There i s also some evidence that boys' achievement exceeds that of g i r l s . The concepts of heat and temperature were selected for study as al t e r n a t i v e b e l i e f s have been investigated for these concepts and are well known. Eight s p e c i f i c questions were addressed and are presented above. Subsequent chapters review the relevant l i t e r a t u r e , describe the methods used for the data c o l l e c t i o n and analysis and present the findings-: The f i n a l chapter presents the conclusions derived from the study and i d e n t i f i e s some areas in need of further investigation. 1.8. Def i n i t i o n s Alternative b e l i e f : a b e l i e f held by a student, which d i f f e r s from the school science view, but which the student accepts as correct. Alternative framework: a coherent set of ideas or expectations students hold about the way natural phenomena occur, which d i f f e r s from the currently accepted school science view and from the intended outcome of learning experiences (after 1 3 D r i v e r , 1981). B e l i e f : any idea that a student accepts as being c o r r e c t . C h i l d r e n ' s s c i e n c e : "those views of the n a t u r a l world and the meanings for s c i e n t i f i c words held by c h i l d r e n before formal s c i e n c e t e a c h i n g " ( G i l b e r t , Osborne and Fensham, 1982, p. 627). Composite s c o r e : a score d e r i v e d s o l e l y f o r the purpose of ranking students a c c o r d i n g to t h e i r p r e t e s t responses, and which has no value i n any a b s o l u t e sense. Conception: a set of r e l a t e d ideas or b e l i e f s which focusses around a s c i e n t i f i c concept; e.g., the concept of heat has s e v e r a l d i f f e r e n t c o n c e p t i o n s . Conceptual c a p t u r e : conceptual change which occurs when a student i s able to r e c o n c i l e new phenomena with e x i s t i n g b e l i e f s . Conceptual exchange: conceptual change which r e q u i r e s that a student r e l i n q u i s h h i s / h e r e x i s t i n g b e l i e f s , i n order to a c q u i r e the new concept. Heat: the t o t a l mechanical energy of a l l of the p a r t i c l e s added up ( a f t e r Schmid and Murphy, 1979, p. 132). 1 4 Idea: any p o s s i b l e view about a s c i e n t i f i c phenomenon; an idea has not n e c e s s a r i l y been accepted as c o r r e c t by the student. Knowledge: f a c t s , ideas and b e l i e f s known to an i n d i v i d u a l as a r e s u l t of experience and/or study. L e a r n i n g : the process of a c q u i r i n g knowledge through experience and/or study. P a r t i c l e s : atoms and/or molecules i n school s c i e n c e . School s c i e n c e : the i n t e r p r e t a t i o n of s c i e n t i f i c phenomena presented by the c u r r i c u l u m , the textbook and the teacher ( a f t e r D r i v e r and E r i c k s o n , 1983). S c i e n t i f i c p e r s p e c t i v e : the s c i e n t i f i c i n t e r p r e t a t i o n of phenomena; in t h i s case, based on the k i n e t i c - m o l e c u l a r theory of matter and energy. S c i e n t i s t s ' s c i e n c e : "the consensual s c i e n t i f i c view of the world and meaning f o r words" ( G i l b e r t et a l . , 1982, p. 627). Sequence: a grouping of q u e s t i o n s and answers d e a l i n g with a s i n g l e t o p i c , u s u a l l y c o n s i s t i n g of a q u e s t i o n , a response and a r e a c t i o n to the response. 1 5 Target students: students selected for in-depth study and representing a range of b e l i e f s about heat and temperature. Temperature: a measure that depends on the average mechanical energy of each p a r t i c l e or the hotness or coldness of something (after Schmid and Murphy, 1979, pp. 132 & 110). 1 6-CHAPTER II REVIEW OF THE LITERATURE 2.0. I n t r o d u c t i o n Three main areas of the resea r c h l i t e r a t u r e were i n v e s t i g a t e d as background to the study: 1. What i s known about how c h i l d r e n l e a r n s c i e n c e concepts--what v a r i a b l e s i n f l u e n c e that l e a r n i n g ? 2. What are c h i l d r e n ' s ideas about heat and temperature? 3. How can we i n v e s t i g a t e the e f f e c t s of c h i l d r e n ' s p r i o r b e l i e f s on the l e a r n i n g of sc i e n c e concepts i n the classroom? T h i s chapter w i l l summarize recent research d e a l i n g with v a r i o u s a spects of these q u e s t i o n s . 2.1. F a c t o r s I n f l u e n c i n g How C h i l d r e n Learn Science Learning may be thought of as the process of a c q u i r i n g knowledge and developing s k i l l s . Hence, i t may seem to f o l l o w that the teacher's r o l e c o n s i s t s of p r e s e n t i n g knowledge and p r o v i d i n g o p p o r t u n i t i e s f o r students to develop s k i l l s . Ausubel has d i s t i n g u i s h e d between two kinds of l e a r n i n g - - r o t e and meaningful l e a r n i n g (Novak, 1977). According to Ausubel, rote l e a r n i n g occurs e i t h e r when the l e a r n e r must r e c i t e something verbatim or when the l e a r n e r has no r e l e v a n t concepts a v a i l a b l e in h i s c o g n i t i v e s t r u c t u r e to which he can r e l a t e the lear n e d m a t e r i a l . For example, a student may be able to c a l c u l a t e the 17 d e n s i t y of an o b j e c t by a p p l y i n g the formula, D=M/V, and be able to repeat the d e f i n i t i o n that " d e n s i t y i s the mass per u n i t volume," yet be unable to r e l a t e the d e f i n i t i o n to the formula and/or to e x p l a i n the meaning of the d e f i n i t i o n . In meaningful l e a r n i n g the new knowledge can be r e l a t e d to r e l e v a n t concepts in the l e a r n e r ' s c o g n i t i v e s t r u c t u r e . Novak a l s o p o i n t s out t h a t these two types of l e a r n i n g are not a dichotomy, but a continuum. 2.1.1. P r i o r B e l i e f s and I n s t r u c t i o n G r i f f i n and Mehan (1981) have s t a t e d : The c o n v e n t i o n a l wisdom about s c h o o l i n g i n c l u d e s the view that c h i l d r e n enter school as t a b u l a r a s a , to be etched with the knowledge necessary not only f o r performance in s c h o o l , but f o r l i f e a f t e r school as w e l l . . . knowledge i s added to knowledge step by step u n t i l the r e q u i s i t e t o t a l amount of c o g n i t i v e and t e c h n i c a l s k i l l s i s reached. Our experience with the t e a c h i n g - l e a r n i n g process i n elementary schools suggests an a l t e r n a t i v e view. I t seems that students come to school with a wide v a r i e t y of experience and v a r y i n g i n t e r p r e t a t i o n s of the world... Thus, i n s t e a d of making e n t r i e s on a blank s l a t e , t e a c h i n g i n school seems to be i n v o l v e d i n e r a s i n g e n t r i e s from a too f u l l s l a t e . (p. 212) G r i f f i n and Mehan view the school c h i l d as an " a c t i v e p a r t i c i p a n t i n the c o n s t r u c t i o n of knowledge, not as a p a s s i v e r e c i p i e n t " (p. 213). T h i s view i s c o n s i s t e n t with P i a g e t i a n theory as w e l l as the concepts of p r i o r c o g n i t i v e s t r u c t u r e s , c r i t i c a l b a r r i e r s , and a l t e r n a t i v e frameworks or conceptions r e f e r r e d to i n the p r e v i o u s c h a p t e r . A l l express the view that c h i l d r e n do i n f o r m a l l y develop b e l i e f s about s c i e n t i f i c phenomena, and that these b e l i e f s are o f t e n incompatible with the s c i e n t i f i c v iewpoint. Pope and G i l b e r t (1983) have s t a t e d : 18 Our main premise i s that s i g n i f i c a n t l e a r n i n g i s l i k e l y to occur only i f the " f a c t s " to be le a r n e d are construed by the l e a r n e r as having p e r s o n a l r e l e v a n c e . We suggest that a " c u l t u r a l t r a n s m i s s i o n " approach to te a c h i n g and knowledge dominates s c i e n c e e d u c a t i o n . T h i s approach has neg l e c t e d the r o l e of students' p e r s o n a l experiences i n t h e i r c o n s t r u c t i o n of knowledge. (p. 193) A c h i l d ' s e s t a b l i s h e d b e l i e f s have presumably been found u s e f u l in the past and resea r c h f i n d i n g s do i n d i c a t e that students are r e l u c t a n t to r e j e c t t h e i r p r i o r b e l i e f s and accept a new po i n t of view. D r i v e r and- E a s l e y (1978) and Osborne and Wittrock (1983) have d i s c u s s e d examples of s t u d i e s i n which i n s t r u c t i o n f a i l e d to r e f u t e students' a l t e r n a t i v e b e l i e f s . Osborne and Wittrock d e r i v e d three major f i n d i n g s from t h e i r review: 1. C h i l d r e n have many f i r m l y h e l d ideas about many sc i e n c e t o p i c s , p r i o r to stu d y i n g s c i e n c e i n s c h o o l . Some of those b e l i e f s are q u i t e d i f f e r e n t from the s c i e n t i f i c view, and the b e l i e f s are not i s o l a t e d ideas, but r a t h e r are "parts of conceptual s t r u c t u r e s which p r o v i d e a s e n s i b l e and coherent understanding of the world from the c h i l d ' s p o i n t of view" (p. 490). 2. C h i l d r e n ' s b e l i e f s can be remarkably r e s i s t a n t to change. 3. I f c h i l d r e n ' s b e l i e f s are changed by s c i e n c e t e a c h i n g , the changes may be r e g r e s s i v e , r a t h e r than p r o g r e s s i v e . They pr o v i d e d the f o l l o w i n g summary of t h e i r review: While c h i l d r e n f r e q u e n t l y pass t e s t s and other formal assessment h u r d l e s , the present s t u d i e s c l e a r l y suggest that c h i l d r e n o f t e n do not r e a l l y change t h e i r ideas of how and why t h i n g s behave as they do as a consequence of sc i e n c e t e a c h i n g . (p. 491) The authors then recommend that s c i e n c e t e a c h i n g b u i l d on students' p r i o r knowledge and b e l i e f s by showing them the inadequacies of t h e i r a l t e r n a t i v e b e l i e f s and h e l p i n g them 19 recognize the v a l i d i t y and u s e f u l n e s s of the s c i e n t i f i c view. C h i l d r e n o f t e n view school s c i e n c e as being d i f f e r e n t than t h e i r r e a l world. In the words of S t r i k e : [ s t u d e nts] are not e x a c t l y overburdened with a need to have what they l e a r n i n s c i e n c e c l a s s e s be c o n s i s t e n t e i t h e r with other s c i e n t i f i c ideas or with t h e i r own experience. Somewhere they have gotten the idea that s c i e n c e i s allowed to be p a r a d o x i c a l and i s not supposed to have anything to do with t h e i r everyday e x p e r i e n c e . ( S t r i k e , 1983, p. 93), and, ...many students approach t h e i r s c i e n c e courses with a d i s t i n c t i o n between the world of ideas and the r e a l world which e a s i l y leads them to di s c o u n t c o n t r a d i c t i o n s between theory and experience. ( S t r i k e , 1983, p. 97) These f i n d i n g s suggest that when a scie n c e concept i s taught i t w i l l meet with v a r y i n g degrees of acceptance from students. Students w i l l recognize that they are expected to " l e a r n " the new concept or point of view, and that they w i l l . be t e s t e d to determine i f that l e a r n i n g has been a c h i e v e d . Some w i l l memorize c e r t a i n aspects of the concept as presented i n c l a s s and/or i n the book, and s u c c e s s f u l l y reproduce what they have " l e a r n e d " when asked. As Doyle (1979, p. 16) has p o i n t e d out, the "performance-grade exchange i s a p r e v a i l i n g r e a l i t y i n classrooms" and l e a r n i n g as determined by w r i t t e n performance does not n e c e s s a r i l y r e f l e c t understanding. The f i n d i n g s d e s c r i b e d above a l s o suggest that we should be c a u t i o u s about assuming that w r i t t e n performance i n d i c a t e s t h at a student b e l i e v e s what he or she w r i t e s on t e s t s or i n w r i t t e n ass ignments. There i s an a d d i t i o n a l concern about the p o s s i b l e e f f e c t s of students not b e l i e v i n g that school s c i e n c e i s r e l e v a n t to t h e i r p e r s o n a l e x p e r i e n c e s . I t may be assumed t h a t there i s 20 l i t t l e , i f any, harm i n t h i s . Some would say that students w i l l l e a r n school s c i e n c e , whether or not they b e l i e v e i t d e s c r i b e s the r e a l world and someday they w i l l recognize the v a l i d i t y of what they have s t u d i e d i n s c h o o l . However, f a i l i n g to see any relevance f o r school s c i e n c e may le a d to negative a t t i t u d e s toward studying s c i e n c e . Pope and G i l b e r t (1983) have suggested, "many students may be 'turned o f f scie n c e because of [the] p e r c e i v e d gap between the content of scie n c e l e s s o n s and t h e i r own world views" (p. 200). In a study i n v e s t i g a t i n g a t t i t u d e s of grade s i x to ten students towards s c i e n c e , Duncan and Haggerty (1985) found that very few students b e l i e v e d the scien c e they learned i n school had anything to do with r e a l l i f e , although they thought that s c i e n c e was very important i n our modern s o c i e t y . T r i p l e t t (1973) s t u d i e d concepts of heat and temperature among nine and ten year o l d s . He f r e q u e n t l y encountered what he c a l l e d the " r e c i t a t i o n syndrome" (which he c o n t r a s t e d to the " i n v e s t i g a t i v e syndrome"). C h i l d r e n o f t e n appeared to be r e c i t i n g i n f o r m a t i o n that had been p r e v i o u s l y a c q u i r e d , even i f t h i s i n f o r m a t i o n was i n c o n s i s t e n t with t h e i r own o b s e r v a t i o n s . T h i s appeared to be an attempt to e l i c i t p o s i t i v e feedback from the i n v e s t i g a t o r , and r e c i t a t i o n appeared to pro v i d e s e c u r i t y f o r most c h i l d r e n . R e c i t a t i o n may occur with or without any r e a l understanding of the concept as r e c i t e d . Among T r i p l e t t ' s s u b j e c t s , a l l but one c h i l d appeared more secure r e c i t i n g than using an i n v e s t i g a t i v e approach. A s i m i l a r s i t u a t i o n was rep o r t e d by D r i v e r (1973) i n her d i s s e r t a t i o n . In d i s c u s s i n g that r e s e a r c h , D r i v e r and E a s l e y (1978) s t a t e d : 21 When an alternate theory was presented either by the teacher or other pupils, which better accounted for the data i t was not necessarily understood, but was accepted and learned at a verbal l e v e l (p. .79). It appears that Ausubel's use of the term "rote" (described e a r l i e r ) i s comparable to T r i p l e t t ' s " r e c i t a t i o n " and Driver's "verbal" learning. Posner et a l . (1982) have proposed that learning i s "best viewed as a process of conceptual change" (p. 213). Kuhn's "normal science" and " s c i e n t i f i c revolutions" (Kuhn, 1970) are seen as analogous to the process of learning science. Normal science i s similar to the situation where a student i s able to incorporate new phenomena into his/her exi s t i n g framework or cognitive structure. However, i f a new phenomenon i s incompatible with an existing framework, then there must be a change in the framework to accommodate the new phenomenon (analogous to a s c i e n t i f i c revolution). The terms, "conceptual capture" and "conceptual exchange" respectively, have been used by Hewson and Hewson (1983) for these two processes. Posner et a l . (1982) i d e n t i f i e d several conditions which must be f u l f i l l e d before conceptual exchange i s l i k e l y to occur: 1. There must be d i s s a t i s f a c t i o n with existing concepts. 2. The new concept must be i n t e l l i g i b l e . That i s , the new knowledge must be understood by the student who can explain what i t means, but he/she may not believe i t i s true. For example, a grade eight student (female, age 13:9) was asked, "What is volume?" Her i n i t i a l response was "the amount of space occupied by an object." Upon probing, t h i s proved to be a memorized d e f i n i t i o n which she could not explain. When asked how she would measure volume, she 22 o f f e r e d t h r e e a l t e r n a t i v e s . One i n v o l v e d m e a s u r i n g a n o b j e c t w i t h a r u l e r a n d c a l c u l a t i n g t h e v o l u m e ( " l e n g t h t i m e s w i d t h " ) . A n o t h e r i n v o l v e d t h e n o t i o n o f v o l u m e a s t h e c a p a c i t y o f a c o n t a i n e r a n d t h e t h i r d m e t h o d u t i l i z e d l i q u i d d i s p l a c e m e n t t o m e a s u r e t h e v o l u m e o f s o l i d o b j e c t s . S h e d i d n o t r e c o g n i z e t h e s e a s a l t e r n a t i v e w a y s o f m e a s u r i n g t h e same t h i n g . R a t h e r , s h e saw t h e m a s t h r e e d i f f e r e n t k i n d s o f v o l u m e , a n d w a s q u i t e c o m f o r t a b l e w i t h t h a t d i s t i n c t i o n . H e r u n d e r s t a n d i n g o f m e a s u r i n g v o l u m e w a s i n t e l l i g i b l e , b u t s h e d i d n o t h a v e a n i n t e g r a t e d c o n c e p t i o n o f t h e t e r m " v o l u m e . " 3. T h e new c o n c e p t m u s t a p p e a r t o b e p l a u s i b l e . T h e new c o n c e p t w i l l n o t a p p e a r p l a u s i b l e u n l e s s i t i s s e e n t o h a v e t h e c a p a c i t y t o r e s o l v e a n o m a l i e s g e n e r a t e d b y t h e e x i s t i n g c o n c e p t . C o n t i n u i n g w i t h t h e e x a m p l e a b o v e , i f " t h e s t u d e n t h a d b e e n a b l e t o i n t e g r a t e h e r v a r i o u s i n t e r p r e t a t i o n s o f t h e t e r m " v o l u m e " a n d t o r e l a t e t h a t t o h e r own e x p e r i e n c e s w i t h v o l u m e ( f o r e x a m p l e , m e a s u r i n g q u a n t i t i e s o f l i q u i d s w h e n c o o k i n g ) , t h e c o n c e p t w o u l d h a v e b e e n p l a u s i b l e . 4. T h e new c o n c e p t m u s t b e f r u i t f u l . I n a d d i t i o n t o b e i n g p l a u s i b l e , t h e new c o n c e p t b e c o m e s p r e f e r a b l e t o t h e e x i s t i n g c o n c e p t . I t i s m o r e u s e f u l a n d e f f i c i e n t , a n d h a s p r e d i c t i v e p o w e r . A t t h i s p o i n t , t h e e x i s t i n g c o n c e p t h a s b e e n e x c h a n g e d f o r t h e new c o n c e p t . L e a r n i n g w h i c h o c c u r s w i t h o u t t h e s e c o n d i t i o n s h a v i n g b e e n m e t i s u n l i k e l y t o b e m e a n i n g f u l l e a r n i n g . T h i s t h e o r y p r o v i d e s a b a s i s f o r i n v e s t i g a t i n g t h e a p p a r e n t t e n a c i t y o f s t u d e n t s ' 23 a l t e r n a t i v e b e l i e f s i n s c i e n c e . The p r e v i o u s chapter r e f e r r e d to the q u e s t i o n of the r e l a t i v e s i g n i f i c a n c e of p r i o r c o g n i t i v e s t r u c t u r e s and of c o g n i t i v e development and t h e i r impact on l e a r n i n g s c i e n c e concepts. While • Shayer and Wylam (1981) recognize the importance of students' p r i o r b e l i e f s , they emphasize the need to c o n s i d e r c h i l d r e n ' s reasoning c a p a c i t i e s as w e l l . They remind the reader that only "about 15 percent of the 12 year-o l d s w i l l possess E a r l y Formal competence" (p. 433) and hence be capable of r e c o g n i z i n g the independence of the three v a r i a b l e s , q u a n t i t y of heat, mass and temperature, when stu d y i n g heat phenomena. The r e l a t i v e importance of c o g n i t i v e development and p r i o r b e l i e f s remains a c o n t r o v e r s i a l i s s u e . Some would suggest that c o g n i t i v e development i s not of p r a c t i c a l s i g n i f i c a n c e , as c o g n i t i v e stages, are not g e n e r a l i z a b l e a c r o s s content areas. I f t h i s were so, i t would mean the stage of any i n d i v i d u a l student must be re-assessed f o r each d i f f e r e n t content area. For example, an i n d i v i d u a l student might demonstrate formal reasoning c a p a c i t i e s when using a balance beam, but not when e x p l a i n i n g heat and temperature phenomena. I f formal reasoning i s not g e n e r a l i z a b l e then i t i s only of t h e o r e t i c a l s i g n i f i c a n c e , r a t h e r than p r a c t i c a l s i g n i f i c a n c e . That i s , a teacher cannot assume that because Susie performs at a formal l e v e l when assessed on one p a r t i c u l a r task, that she w i l l e x h i b i t formal reasoning i n any other s i t u a t i o n . In d i s c u s s i n g t h i s i s s u e , D r i v e r and E a s l e y (1978) s a i d : 24 We suggest t h e r e f o r e that P i a g e t ' s accounts of c h i l d r e n ' s t h i n k i n g in the c a u s a l i t y s t u d i e s , as i n o t h e r s , are important documents but should be read f o r the i n d i c a t i o n s they give of the content of c h i l d r e n ' s ideas and e x p l a n a t i o n s , r a t h e r than as ways of a s s e s s i n g the development of u n d e r l y i n g l o g i c a l s t r u c t u r e s . On the r e l a t e d issue of the uses of P i a g e t i a n tasks f o r a s s e s s i n g p u p i l s ' development i n s c i e n c e , i t would seem more v a l u a b l e i n f o r m a t i o n c o u l d be gained by both c u r r i c u l u m developers and the p r a c t i s i n g teacher through i n t e r v i e w i n g p u p i l s i n order to understand t h e i r ideas and ways of t h i n k i n g about a t o p i c in q u e s t i o n , r a t h e r than as a device f o r c l a s s i f y i n g p u p i l s and p r e s c r i b i n g programmes f o r them, (p. 79) Pope and G i l b e r t have suggested that P i a g e t ' s stage theory has been overemphasized in s c i e n c e e d u c a t i o n . Despite the f a c t that Piaget was c r i t i c a l of those who took the theory of stages to be a s e r i e s of l i m i t a t i o n s , t h i s would appear to be the ' r e c e i v e d view' of many science educators. We would argue that t h i s has been at the expense of the essence of P i a g e t ' s epistemology, i . e . , the c o n s t r u c t i v i s t and r e l a t i v i s t i c view of knowledge in which the person's present c o n s t r u c t i o n of experiences forms the b a s i s f o r the h a n d l i n g of new i n f o r m a t i o n and p r o j e c t i o n s about f u t u r e events. (Pope and G i l b e r t , 1983, p. 196) T h i s i n v e s t i g a t i o n has focussed on students' p r i o r knowledge and i t s r e l a t i o n s h i p to l e a r n i n g . I t i s based on the c o n s t r u c t i v i s t view of knowledge, espoused by P i a g e t and o t h e r s , in the b e l i e f that that view leads to a more f r u i t f u l account of student l e a r n i n g i n a classroom c o n t e x t . 2.1.2. The Influence of Gender The i s s u e of gender e f f e c t s on s c i e n c e achievement remains l a r g e l y s p e c u l a t i v e , although i t i s an issue which i s c u r r e n t l y a t t r a c t i n g a t t e n t i o n a c r o s s Canada and elsewhere. As part of i t s study of Canadian school s c i e n c e , the Science C o u n c i l of Canada sponsored a n a t i o n a l workshop devoted to the the problem of low enrollments of g i r l s i n s c i e n c e (Science C o u n c i l of Canada, 1982). The f o l l o w i n g e x c e r p t s from the B r i t i s h Columbia 25 science assessment reports indicate pronounced differences are found in the achievement of males and females: The outstanding finding of the analysis of achievement results by gender was that there is a s i g n i f i c a n t and substantial difference in knowledge of science concepts favouring boys. (Taylor, 1982, p. 244) ...clear differences were found between the results of male and female students... and [the differences] are most c l e a r l y evident in the grade twelve results (Hobbs et a l . , 1979, p. 95). Following the 1978 B r i t i s h Columbia science assessment, the Ministry of Education commissioned a study of gender and school mathematics and science (Erickson, Erickson and Haggerty, 1980). In 1982 they sponsored a p r o v i n c i a l workshop to make teachers more aware of the lower p a r t i c i p a t i o n and achievement among g i r l s in B r i t i s h Columbia secondary schools. Kelly (1978) has conducted a comprehensive review of the l i t e r a t u r e on t h i s subject. Findings indicate that on the average males outperform females on numerical, mechanical and problem solving s k i l l s . Males have also been shown to consistently achieve higher average scores in s p a t i a l a b i l i t y , which in turn has been shown to be related to achievement in science. Average scores of females are higher in verbal s k i l l s and manual dexterity and appear to be more influenced by the type and content of problems and by motivation. The r e l a t i v e roles of culture and natural or hereditary a b i l i t y in determining these differences have not been i d e n t i f i e d . However, i t seems clear that society at large does not expect or encourage g i r l s to succeed in science, or even to study science, p a r t i c u l a r l y physical science. Undoubtedly one reason for the lower average achievement of grade 12 B r i t i s h Columbia g i r l s on 26 assessment q u e s t i o n s i n p h y s i c s would be the lower enrollment of g i r l s i n s e n i o r secondary p h y s i c s courses. For example, in 1985, 799 females and 3 146 males wrote the p h y s i c s 12 p r o v i n c i a l examination (Kozlow, Note 1). Sadker and Sadker (1985) have r e p o r t e d on a study of s c i e n c e , mathematics and language a r t s c l a s s e s at the grades fo u r , s i x and e i g h t l e v e l s . F i n d i n g s were not r e p o r t e d s e p a r a t e l y by s u b j e c t , but i n a l l c a t e g o r i e s of classroom i n t e r a c t i o n , boys r e c e i v e d more a t t e n t i o n from teachers than d i d g i r l s . A study of grade nine and ten geometry classrooms found that boys were encouraged and c h a l l e n g e d more than were g i r l s (Becker, 1981). In one recent study conducted i n B r i t i s h Columbia (Duncan and Haggerty, 1985), d i f f e r e n t i a l treatment was not observed i n most of the 17 p a r t i c i p a t i n g grade s i x to ten s c i e n c e classrooms (although t h i s may have been i n f l u e n c e d by the teachers' knowledge that the purpose of the study was to i n v e s t i g a t e sex d i f f e r e n c e s i n s c i e n c e achievement and p a r t i c i p a t i o n ) . Kahle, Matyas and Cho (1985) s t u d i e d b i o l o g y c l a s s e s taught by teachers with a r e c o r d of encouraging females in s c i e n c e . Even i n those c l a s s e s , boys r e p o r t e d p a r t i c i p a t i n g in c l a s s a c t i v i t i e s to a g r e a t e r extent than d i d g i r l s . Cannon and Simpson (1985) have r e p o r t e d on a l a r g e s c a l e study of grade s i x to ten s c i e n c e classrooms and concluded that s c i e n c e a t t i t u d e was a good p r e d i c t o r of achievement. They found that boys had a more p o s i t i v e a t t i t u d e toward s c i e n c e and achieved higher i n s c i e n c e , although g i r l s were more motivated to a c h i e v e . The a t t i t u d e q u e s t i o n n a i r e s of the B r i t i s h Columbia 27 s c i e n c e assessment have not r e v e a l e d s i g n i f i c a n t gender d i f f e r e n c e s i n a t t i t u d e s ( T a y l o r , 1982). Duncan and Haggerty (1985) adm i n i s t e r e d the same q u e s t i o n n a i r e s to grade s i x to ten students, and again there were no s i g n i f i c a n t gender d i f f e r e n c e s . However, when the same students were interv i e w e d i n small groups and asked the same q u e s t i o n s that had been on the q u e s t i o n n a i r e , more negative views were expressed. G i r l s i n p a r t i c u l a r , were not i n t e r e s t e d i n pursuing s t u d i e s i n s c i e n c e . The enrollments i n grade 12 s c i e n c e s i n B r i t i s h Columbia a l s o show pronounced gender b i a s , with females comprising 64 percent of the students w r i t i n g the 1985 b i o l o g y 12 examination; 41 percent of chemistry 12; 37 percent of geology 12; and 20 percent of p h y s i c s 12 (Kozlow, Note 1). C l e a r l y , boys and g i r l s do have d i f f e r e n t views about the d e s i r a b i l i t y and/or need to study s e n i o r s c i e n c e , although the causes of these a t t i t u d e s can only be s p e c u l a t e d upon at t h i s time. 2.2. C h i l d r e n ' s B e l i e f s about Heat and Temperature E r i c k s o n (1975), A l b e r t (1974), and T r i p l e t t (1973) have completed d i s s e r t a t i o n s d e a l i n g with c h i l d r e n ' s understanding of heat and temperature. A l b e r t conducted c l i n i c a l i n t e r v i e w s with c h i l d r e n four to nine years o l d . T r i p l e t t , working with nine and ten y e a r - o l d s , a l s o used the c l i n i c a l i n t e r v i e w , but the i n t e r v i e w was based on an experimental apparatus that was p r e s e n t . N e i t h e r of the l a t t e r two s t u d i e s d e a l t with the k i n e t i c framework of heat (the s u b j e c t s were too young). E r i c k s o n , in a p i l o t study f o r h i s d i s s e r t a t i o n , conducted c l i n i c a l . i n t e r v i e w s with c h i l d r e n aged s i x to t h i r t e e n y e ars. 28 Most of the c h i l d r e n i n t e r v i e w e d expressed the f o l l o w i n g b e l i e f s : 1. "heat was thought to be a type of substance which possessed i t s own unique p r o p e r t i e s " 2. "temperature i s a measure of the hotness of an o b j e c t and i s a r e s u l t of the amount of heat that i s added to i t " ( E r i c k s o n , 1975, p. 129). Based on ten in-depth i n t e r v i e w s with 12 y e a r - o l d s , E r i c k s o n developed the "Conceptual P r o f i l e Inventory." The Inventory was then a d m i n i s t e r e d to 276 students i n grades f i v e , seven and nine. Three d i s t i n c t p e r s p e c t i v e s of heat phenomena, which he named " k i n e t i c , " " c a l o r i c " and " c h i l d r e n ' s , " emerged from the data obtained on the Inventory. E r i c k s o n a l s o c o n s i d e r e d p o t e n t i a l a p p l i c a t i o n s to the classroom s i t u a t i o n . Drawing on the tasks i n v e s t i g a t e d i n E r i c k s o n ' s Inventory, Shayer and Wylam (1981) developed a w r i t t e n t e s t , "Heat" (Appendix A ) . The t e s t i n v e s t i g a t e d seven v a r i a b l e s : composition of heat, conduction e f f e c t s , expansion e f f e c t s , chemical e f f e c t s , temperature s c a l e s , change of temperature, and heat/temperature d i f f e r e n t i a t i o n . Three l e v e l s of understanding of heat were i d e n t i f i e d f o r each v a r i a b l e , and these were l i n k e d to P i a g e t i a n stages of development (Table 2.1). The most s o p h i s t i c a t e d l e v e l was predominantly a f l u i d view. The textbook used by the c l a s s s t u d i e d f o r t h i s i n v e s t i g a t i o n (Schmid and Murphy, 1979) presents a view based on k i n e t i c theory, which i s summarized i n Table 2.2. One a d d i t i o n a l set of s t u d i e s should be c o n s i d e r e d here. Novick and Nussbaum (1978; 1981; and Nussbaum and Novick, 1982) 29 Table 2.1 Summaries of Conceptions of Heat and Temperature (Modified from Shayer and Wylam, 1981) Level 1: Phenomenological Conception: For heat, understanding i s phenomenological. It i s associated with burning, melting, etc. Expansion of gases may be seen in terms of 'hot a i r r i s e s ' and because expansion of solids i s seen phenomenologically, i t i s not associated with the necessity of r e v e r s i b i l i t y on cooling. Conduction may be d i f f e r e n t with d i f f e r e n t materials, and with mixing situations the hot gets cooler, and the cool gets warmer. For temperature, on the other hand, the one to one mapping of temperature onto a linear scale i s seen q u a l i t a t i v e l y and indeed semi-quantitatively--'the higher the hotter.' the temperature scale can even be extended with a simple additive strategy. Some but not a l l , grasp temperature as an intensive property; e.g., on mixing a l i q u i d at 25°C with another at 25°C the resultant w i l l be at 25°C. However, some add temperatures. Level 2: Undifferentiated Conception: Temperature i s well conceptualized and quantitive, with m u l t i p l i c a t i v e relations between temperature changes and changes in length of thermometric l i q u i d . Heat i s associated causally not only with the obvious effects (more heat has more e f f e c t ) , but also with less obvious ones such as conduction in gases. Expansion i is now understood as a reversible phenomenon. However, since heat i s conceptualised causally, a model of i t i s not developed at t h i s stage. Thus heat, amount of substance and temperature tend to be collapsed under the single concept of temperature. Provided that only one independent variable i s involved the process w i l l be corr e c t l y conceptualised, e.g., the more the amount of l i q u i d / s o l i d , the more heat w i l l be required to heat i t up, and the more heat that i s added to a given object, the hotter i t w i l l get. Level 3: F l u i d Conception: Interest in how heat causes i t s effects leads to the construction of models for conduction, expansion, heat transfer, etc. A more or less e x p l i c i t model of heat flowing as a l i q u i d from body to body allows quantity of heat, mass and temperature to be d i f f e r e n t i a t e d , with two being used as independent variables in simple calorimetric c a l c u l a t i o n s , i . e . , quantity of heat i s a m u l t i p l i c a t i v e function of both mass and temperature. Thus heat now becomes an extensive property. Theory can be used in contradiction of immediate experience. Although the steel blade of a spade l e f t outside overnight 'feels' colder than the wooden handle, i t i s recognized that t h e i r temperature must be the same, and that the difference in f e e l is due to the greater conductivity of the s t e e l . 30 Table 2.2 Summary of the K i n e t i c Framework (Derived from Schmid and Murphy, 1979) Observations can now be e x p l a i n e d i n terms of the k i n e t i c theory of matter. I t i s recognized that the temperature of an ob j e c t i s due to the rate of motion of the ' p a r t i c l e s . ' Whereas heat energy i s the t o t a l mechanical energy of the p a r t i c l e s , temperature depends on the average mechanical energy of the p a r t i c l e s . Heat t r a n s f e r i s seen in terms of p a r t i c l e motion. S p e c i f i c heat i s a c h a r a c t e r i s t i c p r o p e r t y of matter, and i s not synonymous with the d e n s i t y , or any other c h a r a c t e r i s t i c p r o p e r t y . Thermal expansion i s due to an i n c r e a s e in the mechanical energy of the p a r t i c l e s of an o b j e c t . As the energy-i n c r e a s e s , the p a r t i c l e s move f a s t e r , spreading f u r t h e r a p a r t and the o b j e c t expands. When matter undergoes a change of phase, i t i s due to the i n c r e a s e or decrease i n the average mechanical energy of the p a r t i c l e s ( i . e . , temperature). have i n v e s t i g a t e d c h i l d r e n ' s understanding of the p a r t i c u l a t e nature of matter. One aspect of t h e i r s t u d i e s c o n s i d e r e d the e f f e c t s of h e a t i n g and c o o l i n g on the p a r t i c l e s i n a gas. Few of the 576 students questioned (grades 7 to 12 and second year u n i v e r s i t y non-science majors) e x p l a i n e d the phenomena i n terms of p a r t i c l e motion or energy. Approximately 10 percent of the j u n i o r high students gave an energy or motion response. These f i n d i n g s are s i g n i f i c a n t to the present study, as the textbook d e f i n e s heat and temperature in terms of the mechanical energy of the p a r t i c l e s . 2.3. I n v e s t i g a t i n g the Learning of Science Concepts i n the Classroom Most classroom r e s e a r c h has been aimed at e i t h e r i d e n t i f y i n g c h a r a c t e r i s t i c s of "good t e a c h i n g " as determined by student achievement, or at i n v e s t i g a t i n g s o c i a l i n t e r a c t i o n among stu d e n t s . Most of the s t u d i e s have u t i l i z e d one of the many systems f o r c a t e g o r i z i n g and counting v a r i o u s kinds of 31 behaviour. These systems have tended to concentrate on the frequency of s p e c i f i c teacher behaviours and on learning as measured by mean scores obtained by the students in a c l a s s . One aspect of teacher behaviour which has received p a r t i c u l a r attention i s questioning. Questioning i s often seen as a key to promoting thinking and hence learning. Studies of teachers' questions have attempted to relate the kinds of questions asked to various measures of student achievement and/or attitudes. The use of class or group measures has resulted in the individual student being largely overlooked. As Magoon (1977) has noted, over 50 years of such studies of teacher behaviour have not established li n k s between pa r t i c u l a r i n s t r u c t i o n a l methods and student achievement. This l i n e of research appears to assume that there are universal standards of teaching, irrespective of individual v a r i a t i o n among students and the p r i o r b e l i e f s they bring to the classroom. One recent study of teacher behaviour i s relevant to the present study. Sadker and Sadker (1985) investigated how teachers c a l l e d on students and how they responded to student comments in 100 grade four, six and eight classrooms. Teacher responses were found to be very neutral. Over half of a l l responses were categorized as "acceptance," and consisted of a comment that implied that an answer was acceptable, but was not e x p l i c i t (e.g., "I see," "uh-huh"). There was a corresponding lack of " c r i t i c i s m " responses—that i s , responses in which the teacher c l e a r l y indicated that an answer was inaccurate. The authors suggest that the predominance of neutral responses, 32 coupled with the lack of frequent p r a i s e or c r i t i c i s m , d e p r i v e s students of adequate feedback as to the q u a l i t y of t h e i r responses. In approximately one-half of the classrooms observed, a few students r e c e i v e d a p r o p o r t i o n a l l y l a r g e share of the i n t e r a c t i o n s . In a l l classrooms, approximately one-q u a r t e r of the students d i d not p a r t i c i p a t e at a l l . The authors concluded, "Our data suggest that classroom i n t e r a c t i o n s between teachers and students are short on both q u a l i t y and e q u a l i t y . " As w i l l be seen, Sadker and Sadker's f i n d i n g s were very s i m i l a r to those of the c u r r e n t i n v e s t i g a t i o n . A l t e r n a t i v e b e l i e f s or frameworks have been s t u d i e d using the c l i n i c a l i n t e r v i e w approach (e.g., E r i c k s o n , 1975; Novick and Nussbaum, 1978; T r i p l e t t , 1973) and group t e s t s (e.g., E r i c k s o n , 1975; Novick and Nussbaum, 1981; Shayer and Wylam, 1981) and/or what might be c a l l e d "micro-teaching" s i t u a t i o n s ( c o n s i s t i n g - of a small number of students and a teacher i n a pseudo-classroom s i t u a t i o n ; e.g., T i b e r g h i e n , 1979). Only one study ( D r i v e r , 1973) has been found i n which frameworks were s t u d i e d i n an a c t u a l classroom s i t u a t i o n . Delacote (1980) has urged that d e s c r i p t i v e r e s e a r c h , emphasizing student behaviour, can f i l l t h i s need. One way to i n v e s t i g a t e the i n t e r a c t i o n of student b e l i e f s and teacher s t r a t e g i e s would be through an o b s e r v a t i o n a l study of the ways in which students make sense of an ongoing i n s t r u c t i o n a l sequence. S t u d i e s by D r i v e r (1973) and T i b e r g h i e n (1979) are c i t e d as exemplars of t h i s method. Both of these s t u d i e s emphasized i n t e r a c t i o n s w i t h i n a small group s e t t i n g . D r i v e r s t u d i e d four students i n t h e i r own classroom. The c l a s s being 33 s t u d i e d had a l a r g e area a v a i l a b l e , c o n s i s t i n g of a l e c t u r e room and two l a b o r a t o r i e s . T h i s p e r m i t t e d the students to spread out du r i n g l a b o r a t o r y p e r i o d s , minimizing the problem of c o n c e n t r a t i n g on the students being s t u d i e d . T i b e r g h i e n s t u d i e d e i g h t c h i l d r e n as they were taught about heat i n a t e l e v i s i o n s t u d i o "very c l o s e " to t h e i r own s c h o o l , r a t h e r than i n an a c t u a l classroom. The teacher was from t h e i r s c h o o l . Neither of these s t u d i e s i n v e s t i g a t e d the i n t e r a c t i o n s between a teacher and an e x i s t i n g c l a s s of students, d u r i n g r e g u l a r i n s t r u c t i o n . 2.4. Summary The review of the l i t e r a t u r e suggests that students' l e a r n i n g may be g r e a t l y i n f l u e n c e d by t h e i r p r i o r b e l i e f s ; in f a c t , p r i o r b e l i e f s may serve as a c r i t i c a l b a r r i e r to l e a r n i n g f o r some students. Because students are s t r o n g l y motivated to pr o v i d e c o r r e c t answers, they may do so based on memory rather than on understanding. Ausubel has r e f e r r e d to these two kinds of l e a r n i n g as " r o t e " and "meaningful l e a r n i n g . " Others have used d i f f e r e n t terms f o r a s i m i l a r d i s t i n c t i o n . Compared to boys, g i r l s appear to be at a disadvantage i n l e a r n i n g s c i e n c e . D i f f e r e n t i a l treatment by teachers and d i f f e r e n t i a l p r i o r b e l i e f s may be f a c t o r s i n observed d i s c r e p a n c i e s . Students' concepts of heat and temperature have been c l a s s i f i e d i n t o four l e v e l s of understanding: phenomenological, u n d i f f e r e n t i a t e d , f l u i d and k i n e t i c . At the j u n i o r secondary l e v e l few students express e i t h e r the f l u i d or the k i n e t i c l e v e l . In recent years classroom r e s e a r c h e r s have i n c r e a s i n g l y 34 concluded that studies which have concentrated on teacher behaviour have not provided the sought after answer to the question, "how can teaching be improved?" It has been suggested that looking at the b e l i e f s individual students bring to the classroom, and at the interaction of these b e l i e f s with instruction as they learn may be a more productive l i n e of research. This was the major objective of the present study. The next chapter describes the methods used to investigate t h i s problem. 35 CHAPTER I I I METHODOLOGY: COLLECTING THE DATA 3.0. I n t r o d u c t i o n T h i s study i n v e s t i g a t e d the development of the concepts of heat and temperature while these t o p i c s were being s t u d i e d by a grade nine s c i e n c e c l a s s . As t h i s type of study has not p r e v i o u s l y been rep o r t e d i n the l i t e r a t u r e , the methods were p r i m a r i l y e x p l o r a t o r y . "It was a n t i c i p a t e d that the f i n d i n g s would l e a d to the generation of hypotheses which c o u l d be t e s t e d i n f u t u r e s t u d i e s , as w e l l as ad d r e s s i n g the qu e s t i o n s posed e a r l i e r . The school s e l e c t e d f o r the study was an urban, upper-middle c l a s s , lower mainland secondary school o f f e r i n g grades e i g h t through twelve. The school was s e l e c t e d on the b a s i s of two c r i t e r i a : the absence of a l a r g e non-English speaking community, and the w i l l i n g n e s s of the s t a f f to p a r t i c i p a t e . In the former i n s t a n c e , i t was judged that the r e s u l t s of the study would depend upon the students' a b i l i t i e s to express t h e i r i deas, both o r a l l y and i n w r i t t e n work, and that f a c i l i t y with the E n g l i s h language was e s s e n t i a l . The teachers i n the school were informed that the researcher was conducting a study of d i f f i c u l t i e s students have i n understanding the concepts of heat and temperature as presented i n the grade nine s c i e n c e course, and . that t h i s t o p i c had been s e l e c t e d as i t appears to present d i f f i c u l t i e s f o r many students. 36 An a c c r e d i t a t i o n review of the school had been conducted the p r e v i o u s year. The i n t e r n a l r e p o r t of the a c c r e d i t a t i o n committee pr o v i d e d the f o l l o w i n g i n f o r m a t i o n d e r i v e d from responses to a q u e s t i o n n a i r e sent to randomly s e l e c t e d p a r e n t s : most of the respondents l i v e d i n s i n g l e f a m i l y homes and 63 percent had l i v e d i n the area more than 10 y e a r s ; 64 percent were s i n g l e income f a m i l i e s , but only 14 percent were s i n g l e parent f a m i l i e s ; E n g l i s h was the language spoken i n 97 percent of the homes; 97 percent of the parents expected t h e i r c h i l d r e n to continue to post-secondary education a f t e r completing high s c h o o l ; 69 percent expected t h e i r c h i l d r e n to a t t e n d u n i v e r s i t y ; 21 percent gave the school an o v e r a l l r a t i n g of " e x c e l l e n t " and 64 percent r a t e d the school as "good." The s c h o o l emphasized academic programs. The committee noted t h a t , as a r e s u l t , " U n f o r t u n a t e l y , many students whose i n t e r e s t s and a b i l i t i e s l i e elsewhere are f o r c e d to pursue programmes with which' they cannot cope." The reviewers a l s o noted that two of the s c i e n c e classrooms were very small and had only one s i n k . T h e i r storage space and number of e l e c t r i c a l o u t l e t s were judged to be inadequate. One such classroom was the s e t t i n g f o r t h i s study. The room had o r i g i n a l l y been a r e g u l a r classroom, and was l a t e r c onverted to a s c i e n c e l a b o r a t o r y . O v e r a l l , the school and community were such that there was an absence of many of the disadvantages faced by some s c h o o l s . I t was assumed that i f students a t t e n d i n g t h i s school experienced d i f f i c u l t i e s with the u n i t on heat and temperature, then we c o u l d a n t i c i p a t e that s i m i l a r d i f f i c u l t i e s might be expected to occur i n many, i f not most, s c h o o l s . 37 The data were co l l e c t e d in three phases. Phase I was intended to provide background information on the textbook as a source of information, on the students in the class and on the teacher's approach to teaching science. Interviews were conducted with selected target students. It also provided time for the investigator to " s e t t l e i n " and become an accepted member of the c l a s s . Phase II involved recording the dai l y happenings of the class during i t s study of the chapters on heat and temperature. The target students had been selected for more in-depth study during t h i s phase. The f i n a l phase consisted of the unit test and the posttest. A p i l o t study provided a preliminary view of student responses to the unit. 3.1. Phase I Phase I of the study was conducted before the unit on heat and temperature was taught. The teacher was interviewed to discuss the researcher's plans, to ensure that the teacher was a w i l l i n g participant and to discuss her approach to teaching the unit. The teacher expressed willingness to participate and interest in the questions being addressed by the study. Before the study of heat and temperature began, the investigator sat in on the science classes, in order to accustom the teacher and the students to her presence. A two week period was o r i g i n a l l y planned. However, for a variety of reasons, the teacher did not begin the unit u n t i l much later than intended. As a r e s u l t , the Phase I observation period lasted six weeks. Observations recorded during that period were used to investigate the f e a s i b i l i t y of p a r t i c u l a r data-gathering 38 techniques. They were not used as data f o r the study. 3.1.1. The P r e t e s t During the f i r s t week, one c l a s s p e r i o d was p r o v i d e d to t e s t students' concepts of heat and temperature. Two students were absent that day and were sent to the l i b r a r y the f o l l o w i n g p e r i o d to complete the t e s t . The t e s t used was "Heat" (Appendix A), developed at Chelsea C o l l e g e , London (Shayer and Wylam, 1981). The authors a d m i n i s t e r e d the t e s t to s i x c l a s s e s of students aged nine to t h i r t e e n . The r e l i a b i l i t y (KR20) of the t e s t was 0.894. F a c t o r a n a l y s i s i d e n t i f i e d only one s i g n i f i c a n t f a c t o r , accounting f o r 38.8 percent of the v a r i a n c e . In the c u r r e n t study, s c o r i n g of the t e s t items was based on the authors' c r i t e r i a , p r ovided to the i n v e s t i g a t o r by Shayer (Note 3). The t e s t c o n s i s t s of 60 items c o v e r i n g seven t o p i c s : temperature s c a l e s , change of temperature, expansion of heat, matter and heat, composition of heat, temperature and heat, and movement of heat. Each item had been c a t e g o r i z e d by the developers on the b a s i s of two c r i t e r i a - - t o p i c and l e v e l of understanding. In the l a t t e r case, each a c c e p t a b l e response to each item was c a t e g o r i z e d as one of three l e v e l s of understanding (see Table 2.1). For example, i n one set of q u e s t i o n s students are asked to p r e d i c t what w i l l happen when a n a i l which has been heated to 500°C i s dropped i n t o a g l a s s of water at 18°C (see q u e s t i o n set B, Appendix A). Students who c o r r e c t l y p r e d i c t t h a t the temperature of the n a i l w i l l drop and of the water w i l l r i s e (items B1 and B2) demonstrate L e v e l 1 understanding. Students who e x p l a i n t h i s o b s e r v a t i o n using a k i n e t i c model ( i . e . , i n terms of p a r t i c l e s and t h e i r motion) 39 demonstrate Level 3 understanding on item B3. Students are then asked to guess the actual temperatures 1, 5, 10, 15 and 30 minutes after the n a i l i s dropped into the water (item B4). Three alternative patterns of response to t h i s question were described by the authors: Level 1: a continuous drop in the temperature of the n a i l and a continuous r i s e in the temperature of the water; Level 2: the temperature of the n a i l drops, but the temperature of the water increases i n i t i a l l y and then decreases; and Level 3: the temperature of the n a i l decreases very rapidly and the temperature of the water increases at a slower rate u n t i l both are at the same temperature, and then both gradually cool to room temperature. The levels for the item responses were determined from Piaget's reported three levels of children's responses -*to experiments on the transmission, conduction and equalization of heat (Piaget, 1974) . Each item was also assigned to one or more of the seven topics. With respect to topic, the n a i l and water items were categorized as follows: Change of temperature: item B4 Composition of heat: item B3 Temperature and heat: items B1, 2 and 4, and Movement of heat: items B1, 2 and 3. The r e l i a b i l i t y (internal consistency) of the t o t a l pretest was 0.87. Subscale r e l i a b i l i t i e s for Levels 1, 2 and 3 respectively were: 0.81, 0.70 and 0.38. The r e l i a b i l i t i e s for the topic subscales ranged from 0.14 to 0.76. A low r e l i a b i l i t y indicates 40 a lack of consistency in item responses on that subscale. On the one hand, th i s may be somewhat related to the small number of items per subscale. Four topic subscales had only seven items each and their r e l i a b i l i t i e s were 0.32, 0.49, 0.52, and 0.58. However, the "composition of heat" topic (11 items) had a r e l i a b i l i t y of 0.14, and "expansion of heat" (nine items) had a r e l i a b i l i t y of 0.76. These findings suggest that the most important factor influencing the r e l i a b i l i t y was the actual inconsistency in the responses. This could be caused by students either f a i l i n g to answer many of the questions and/or guessing at the answers. A system of ranking the students according to their understanding of heat and temperature concepts was required to enable the investigator to select target students with varying levels of understanding. For each topic, each student was assigned to one of the three levels described by Shayer and Wylam (1981), with the exception that the topic "temperature scales" has only two l e v e l s . Composite scores were determined by finding the sum of the levels obtained on the seven topics. For example, a student scoring at the maximum le v e l on a l l topics would be c l a s s i f i e d at Level 3 on six topics and at Level 2 on the seventh, for a composite score of 20 (6 X 3 + 2). On the basis of the composite scores students were divided into three groups: the top t h i r d (Group T), middle t h i r d (M) and bottom t h i r d (B). 41 3.1.2. S e l e c t i o n of Target Students Target students were s e l e c t e d f o r i n t e r v i e w and f o r i n -depth study d u r i n g Phase I I , as i t was a n t i c i p a t e d t h a t i t would be impossible to c l o s e l y monitor more than e i g h t students d u r i n g c l a s s time. The f o l l o w i n g c r i t e r i a were used i n the s e l e c t i o n of the t a r g e t students: 1. There should be equal numbers of males and females. 2. Students s e l e c t e d should be among those who f r e q u e n t l y c o n t r i b u t e to c l a s s d i s c u s s i o n s to ensure maximum data. 3. The s e l e c t e d students should represent a c r o s s s e c t i o n of the range of ideas and b e l i e f s present in the c l a s s . In order to ensure that t h i s c r i t e r i o n was met, students were d i v i d e d i n t o three groups a c c o r d i n g to composite s c o r e s . One t a r g e t student of each sex was chosen from each of the top and bottom groups. The t e a c h e r ' s estimate of each student's a b i l i t y and e f f o r t was a l s o obtained and c o n s i d e r e d . 4. When one student was s e l e c t e d , h i s / h e r l a b o r a t o r y p a r t n e r was a l s o s e l e c t e d . Although i t may have seemed d e s i r a b l e to match l a b o r a t o r y p a r t n e r s a c c o r d i n g to l e v e l s of understanding, t h i s was not attempted as i t would have d i s r u p t e d the r o u t i n e of the c l a s s . Barnes and Todd (1975) have rep o r t e d on d i f f i c u l t i e s encountered when student groups were assigned by the r e s e a r c h e r , rather than s e l f -s e l e c t e d . Assigned groups were found to c r e a t e an a r t i f i c i a l s i t u a t i o n and to i n h i b i t the i n t e r a c t i o n among the students. A l l students are i d e n t i f i e d by pseudonyms. The s e l e c t e d 42 students were Jane (Group T) and her p a r t n e r , Cathy (M); Joe (T) and p a r t n e r , Alan ( T ) ; Susan (B) and p a r t n e r , Carolyn (M); and Gordon (B) and p a r t n e r , B r i a n (M). Jane had the highest s c i e n c e marks in the c l a s s and was d e s c r i b e d by the teacher as above average in both a b i l i t y and e f f o r t . Cathy was d e s c r i b e d as an above average student i n both a b i l i t y and e f f o r t . Joe was c o n s i d e r e d to be of above average a b i l i t y , but was d e s c r i b e d as " l a z y . " Alan was s a i d to be of average a b i l i t y , but to have very poor work h a b i t s . Alan was r e p e a t i n g grade nine s c i e n c e . His p r e t e s t responses i n d i c a t e d a p a r t i c u l a r l y good understanding of the concepts of heat and temperature. Susan was judged to be below average i n a b i l i t y and Carolyn to be average. Both g i r l s were c l a s s i f i e d as average with respect to e f f o r t . The teacher f e l t that Gordon was " b r i g h t , " but i n d i c a t e d that h i s achievement was below average. She a t t r i b u t e d t h i s to very poor work h a b i t s . B r i a n was d e s c r i b e d as an average student i n both r e s p e c t s . 3 .1.3. Target Student Interview Target students were i n t e r v i e w e d to o b t a i n a d d i t i o n a l i n f o r m a t i o n on p r e t e s t responses, using a c l i n i c a l i n t e r v i e w approach (Appendix B). Students were asked to e x p l a i n more f u l l y the reasons f o r t h e i r responses on the t e s t , p a r t i c u l a r l y those responses which represented lower l e v e l responses or r e v e a l e d a l t e r n a t i v e b e l i e f s . T h i s was to allow the i n v e s t i g a t o r to explore the reasoning of students who d i d not u t i l i z e the s c i e n t i f i c view. 43 3.1.4. Curriculum and Textbook Analysis A brief content analysis was conducted of the relevant sections of the curriculum guide (Curriculum Development Branch, 1979), the textbook (Schmid and Murphy, 1979) and the teachers' guide (Schmid, Murphy and Williams, 1980) to identify the following: 1. What concepts are presented in the unit? 2. What essential learning outcomes are prescribed by the curriculum? 3. What are the prerequisite concepts that students are expected to understand? 4. How do the curriculum guide and the teachers' guide assist the teacher with.respect to teaching the unit? 5. How does the textbook present and discuss the concepts? 6. To what extent do the curriculum, textbook and teachers' guide take account of the possibility that students may hold alternative beliefs? 3.1.5. Summary Phase I extended over a six-week interval, immediately preceding instruction on heat and temperature. The six weeks of observation provided ample opportunity to get to know the individual students and to determine how to most effectively record the class discussions. The pretest was administered and scored, the target students were selected and they had a l l been interviewed well before the unit began. By the time Phase I concluded, the investigator felt confident that her presence was largely overlooked by the students. This conclusion was supported by the frequent observation after the third week that 4 4 w h e n t h e t e a c h e r l e f t t h e r o o m , t h e s t u d e n t s ' b e h a v i o u r c h a n g e d i m m e d i a t e l y . When a n o t h e r t e a c h e r l o o k e d i n t o t h e r o o m , t h e y i m m e d i a t e l y q u i e t e n e d d o w n . T h e p r e s e n c e o f t h e i n v e s t i g a t o r a p p e a r e d t o h a v e n o i n h i b i t o r y e f f e c t w h a t s o e v e r . 3 . 2 . P h a s e I I T h e m a j o r p a r t o f t h e d a t a c o l l e c t i o n b e g a n w h e n t h e c l a s s b e g a n c h a p t e r s e v e n o f t h e e n e r g y u n i t , " H e a t E n e r g y . " C l a s s r o o m d a t a w e r e g a t h e r e d w i t h t w o m a j o r q u e s t i o n s i n m i n d : 1 . How d o e s t h e s t u d e n t r e s p o n d t o i n s t r u c t i o n a n d i n s t r u c t i o n a l m a t e r i a l s ? 2 . How d o e s t h e t e a c h e r p r o v i d e f o r l e a r n i n g ? T o a d d r e s s t h e f i r s t q u e s t i o n , t h e r e s e a r c h e r e x a m i n e d s t u d e n t r e s p o n s e s a n d b e h a v i o u r i n c l a s s , s t u d e n t i n t e r v i e w s a n d a l l w r i t t e n w o r k c o m p l e t e d b y t h e s t u d e n t s ( i n c l u d i n g t e s t s ) . P a r t i c u l a r a t t e n t i o n w a s p a i d t o t h e t a r g e t s t u d e n t s . T e a c h e r i n t e r v i e w s a n d c l a s s d i s c u s s i o n s p r o v i d e d d a t a t o a d d r e s s t h e s e c o n d q u e s t i o n . C l a s s r o o m d a t a w e r e c o l l e c t e d a t t w o l e v e l s : l a r g e g r o u p a n d s m a l l g r o u p . L a r g e g r o u p d a t a w e r e c o l l e c t e d w h e n t h e t e a c h e r was p r o v i d i n g i n f o r m a t i o n a n d / o r i n t e r a c t i n g w i t h t h e c l a s s a s a w h o l e . O b s e r v a t i o n s w e r e made o f t h e b e h a v i o u r a n d a c t i v i t i e s o f a l l s t u d e n t s a n d o f t h e i n s t r u c t i o n p r o v i d e d . S m a l l g r o u p d a t a w e r e c o l l e c t e d w h e n t h e s t u d e n t s w e r e w o r k i n g i n d i v i d u a l l y o r i n l a b o r a t o r y g r o u p s . A t t h o s e t i m e s , t h e t a r g e t s t u d e n t s w e r e t h e f o c u s o f a t t e n t i o n . Two t y p e s o f d a t a w e r e c o l l e c t e d . E t h n o g r a p h i c d a t a c o n s i s t e d o f n o t e s t a k e n b y t h e i n v e s t i g a t o r d u r i n g t h e c l a s s e s . T h i s w r i t t e n r e c o r d o f a l l 45 c l a s s o b s e r v a t i o n s i n c l u d e d d e t a i l s s u c h as i n f o r m a t i o n w r i t t e n on t h e c h a l k b o a r d o r o v e r h e a d p r o j e c t o r , a c t i o n s o f s t u d e n t s and a r e c o r d o f t h e names of s t u d e n t s who were s p e a k i n g . In a d d i t i o n , a l l c l a s s e s were a u d i o - t a p e r e c o r d e d . The t a p e s and t h e w r i t t e n o b s e r v a t i o n s were u s e d t o p r e p a r e a r o u g h t r a n s c r i p t o f e a c h l e s s o n . S t u d e n t - t e a c h e r d i a l o g u e d u r i n g c l a s s d i s c u s s i o n s was t h e n c o d e d on a d a t a form u s i n g t h e t r a n s c r i p t s , o b s e r v a t i o n s and t h e t a p e d r e c o r d . A t o t a l o f 160 m i n u t e s ( f r o m e i g h t of t h e n i n e p e r i o d s ) were d e v o t e d t o d i s c u s s i o n o r d i a l o g u e between t h e t e a c h e r and t h e e n t i r e c l a s s . The d i a l o g u e was c o d e d w h i l e l i s t e n i n g t o t h e t a p e s and f o l l o w i n g a l o n g . w i t h t h e t r a n s c r i p t s . The f o l l o w i n g c a t e g o r i e s f o r t h e s t u d e n t s ' r e s p o n s e s a r e b a s e d on t h e e x t e n t t o which t h e r e s p o n s e was c o n s i s t e n t w i t h t h e s c h o o l s c i e n c e v i e w : C o r r e c t : t h e answer was c o m p l e t e and c o r r e c t . A l t e r n a t i v e b e l i e f : • t h e answer was not c o m p l e t e l y c o n s i s t e n t w i t h t h e s c h o o l s c i e n c e p e r s p e c t i v e , but was a l o g i c a l i d e a and was a b e l i e f h e l d by more t h a n one s t u d e n t . P a r t i a l l y c o r r e c t : t h e answer was e i t h e r p a r t i a l l y i n c o r r e c t o r i t was i n c o m p l e t e . I n c o r r e c t : t h e r e s p o n s e was c o m p l e t e l y i n c o r r e c t . No r e s p o n s e : t h e s t u d e n t d i d n o t a t t e m p t t o answer t h e q u e s t i o n . A l l s t u d e n t r e s p o n s e s were c o d e d as t o t h e i d e n t i t y of t h e r e s p o n d a n t a s w e l l . Two a s p e c t s of t h e t e a c h e r ' s r e s p o n s e s t o s t u d e n t answers were o f c o n c e r n . The f i r s t was how t h e t e a c h e r e v a l u a t e d t h e a c c u r a c y of t h e s t u d e n t s r e s p o n s e . S e c o n d l y , i f t h e s t u d e n t answer was n o t c o m p l e t e and c o r r e c t , how d i d t h e t e a c h e r go 46 about e l i c i t i n g the d e s i r e d response or i n f o r m a t i o n . The f o l l o w i n g c a t e g o r i e s were used to code the teacher's responses to the student answers: Acknowledge: a comment was made to i n d i c a t e acceptance of the student's answer; e.g., t h a t ' s r i g h t ; very good; mhmm. Wrong answer: the teacher s p e c i f i c a l l y s t a t e d that the answer was not c o r r e c t . Encourage/explore: the teacher probed or questioned the respondant to draw out more i n f o r m a t i o n . R e d i r e c t : the teacher asked another student to respond to the same q u e s t i o n . Provide i n f o r m a t i o n : a b r i e f response i n which the teacher p r o v i d e d s p e c i f i c f a c t s about the t o p i c i n q u e s t i o n . E x p l a n a t i o n : the teacher e x p l a i n e d , o f t e n at l e n g t h , a concept that the respondant d i d not understand. Demonstration: the teacher used a p h y s i c a l demonstration to i l l u s t r a t e a phenomenon. Repeat: the teacher repeated the student's response. Ignore/di smi s s : the teacher e i t h e r ignored the response or i n d i c a t e d t h at she d i d not want to hear what the respondant had to say at that time. M a n a g e r i a l : the teacher's response addressed the student's behaviour, r a t h e r than the content of a response. The coding a l s o i n d i c a t e d i f the teacher c a l l e d on a s p e c i f i c student by name ( i f a gesture was used i t was not recorded as the data were d e r i v e d from an a u d i o - t a p e ) . Sometimes a student i n i t i a t e d d i a l o g u e on a p a r t i c u l a r t o p i c . T h i s was a l s o coded to i n d i c a t e whether i t was i n the 47 form of a quest i o n or a statement of i n f o r m a t i o n . Each coded category was t a b u l a t e d by gender of student to o b t a i n i n f o r m a t i o n on any d i f f e r e n c e s i n responses to or from male and female students. Summary t a b l e s of student-teacher d i a l o g u e were prepared from the coded data forms. Small group data were d e r i v e d from the recorded o b s e r v a t i o n s and t r a n s c r i p t s of the c l a s s e s . These data were e s s e n t i a l l y q u a l i t a t i v e and anecdotal i n nature, and r e l a t e d to the a c t i v i t i e s of the t a r g e t students d u r i n g l a b o r a t o r y i n v e s t i g a t i o n s . 3.2.1. L e a r n i n g : How Does the Student Respond to I n s t r u c t i o n and I n s t r u c t i o n a l M a t e r i a l s ? T h i s aspect of the data c o l l e c t i o n looked p r i m a r i l y at the ta r g e t students, although r e l e v a n t data on other students were a l s o c o n s i d e r e d . I n t e r a c t i o n s between the teacher and students, as w e l l as student-student i n t e r a c t i o n s were examined 1. In l a r g e group a c t i v i t i e s the teacher was the primary " a c t o r . " However, students both responded to and r a i s e d q u e s t i o n s , and made comments d u r i n g the l e s s o n s . Observations were made to determine what students d i d when they appeared to be having d i f f i c u l t i e s understanding presented m a t e r i a l or when they had qu e s t i o n s or comments to make du r i n g the l e s s o n . During l a b o r a t o r y i n v e s t i g a t i o n s the i n v e s t i g a t o r observed the t a r g e t students to determine the ways i n which they approached an a c t i v i t y , i n v e s t i g a t i o n or assignment, the s t r a t e g i e s used to complete the task, i n c l u d i n g the r o l e s p l a y e d by each student, and the r e s u l t s o btained. Photocopies were made of a l l w r i t t e n work submitted by the t a r g e t students. 48 C h e c k - l i s t s were used to summarize the w r i t t e n work of other students and i n d i c a t e d whether answers were c o r r e c t or i n c o r r e c t , as w e l l as i d e n t i f y i n g the a l t e r n a t i v e b e l i e f s expressed by the students. The summaries made i t p o s s i b l e , f o r example, to r e a d i l y recognize that one assigned q u e s t i o n which was fundamental to understanding the meaning of the c a l o r i m e t r y i n v e s t i g a t i o n (1.42), was answered i n c o r r e c t l y by a l l but one student. A l l of the students' w r i t t e n work was examined in r e l a t i o n to the observed a c t i v i t i e s . The data were recorded with the f o l l o w i n g kinds of q u e s t i o n s i n mind: 1. How does the student r e l a t e the i n v e s t i g a t i o n / a c t i v i t y to the concept(s) being studied? 2. How does the student e x p l a i n the concept being i n v e s t i g a t e d ? Is an a l t e r n a t i v e b e l i e f u t i l i z e d ? What evidence does the student provide to support h i s / h e r a l t e r n a t i v e b e l i e f ? 3. Does the student who expresses an a l t e r n a t i v e b e l i e f r e c o g n i z e anomalies i n that view? 4. To what extent does the student see the school s c i e n c e view as i n t e l l i g i b l e ? p l a u s i b l e ? f r u i t f u l ? Whenever p o s s i b l e , student b e l i e f s expressed i n c l a s s were checked out by r e f e r r i n g t o t h e i r w r i t t e n work as w e l l . 3.2.2. I n s t r u c t i o n : How Does the Teacher Provide f o r Learning? Two major types of a c t i v i t i e s o ccurred i n the l a r g e g r o u p -l e c t u r e or e x p l a n a t i o n i n which the teacher d i d most of the t a l k i n g , and d i s c u s s i o n or question-answer s i t u a t i o n s i n which students c o n t r i b u e d to a major p o r t i o n of the c o n v e r s a t i o n or d i a l o g u e . 49 In l a r g e group a c t i v i t i e s the teacher may have been i n t r o d u c i n g new m a t e r i a l or concepts, conducting a " p r e l a b . " or " p o s t l a b . " s e s s i o n , r e - t e a c h i n g m a t e r i a l that was not w e l l understood p r e v i o u s l y or t a k i n g up assignments. Data were c o l l e c t e d with the f o l l o w i n g kinds of qu e s t i o n s i n mind: 1. How does the teacher introduce new concepts? 2. How does the teacher p r o v i d e f o r student input and feedback? For example, does the teacher e x p l o r e student's p r i o r b e l i e f s about r e l e v a n t concepts while i n t r o d u c i n g new ideas? 3. What s t r a t e g i e s does the teacher use to take i n t o account student feedback? Does the teacher c h a l l e n g e students to modify t h e i r a l t e r n a t i v e b e l i e f s ? 4. What s t r a t e g i e s does the teacher provide to allow students to s h i f t from an a l t e r n a t i v e b e l i e f to the school s c i e n c e view? 3.3 Phase III Upon completion of the u n i t , students were r e - t e s t e d using a very s l i g h t l y r e v i s e d v e r s i o n of the p r e t e s t . For example, numbers and names of substances and o b j e c t s were changed where f e a s i b l e . The purpose of the p o s t t e s t was to i d e n t i f y the conceptions used by each student upon completion of the u n i t . The r e l i a b i l i t y of the t o t a l p o s t t e s t was 0.90; f o r L e v e l s 1, 2 and 3 r e s p e c t i v e l y , i t was 0.81, 0.85 and 0.58. There was no change i n the r e l i a b i l i t y of the L e v e l 1 s u b s c a l e . The other subscales showed an i n c r e a s e i n r e l i a b i l i t y . The responses on the u n i t t e s t (Appendix C), prepared by the teacher and 50 administered the same day as the p o s t t e s t , were a l s o used as a data source. 3 . 4 . Summary T h i s chapter has d e s c r i b e d the methods used to c o l l e c t and analyse the data. Phase I c o n s i s t e d of an o r i e n t a t i o n p e r i o d for the i n v e s t i g a t o r . The students' p r i o r b e l i e f s about heat and temperature were assesssed using a p r e t e s t and i n t e r v i e w s with e i g h t s e l e c t e d t a r g e t s t u d e n t s . The u n i t on heat and temperature was s t u d i e d d u r i n g a two-week i n t e r v a l , comprising Phase II of the study. A l l l e s s o n s were audio-taped and t r a n s c r i b e d . The i n v e s t i g a t o r also' recorded the a c t i v i t i e s of the students and the teacher i n note form d u r i n g the l e s s o n s . Student-teacher d i a l o g u e was coded and analysed as d e s c r i b e d in t h i s chapter. The students' w r i t t e n work was c o l l e c t e d and analysed. - The f i n a l day of the study, Phase I I I , the students wrote the p o s t t e s t and the teacher-made u n i t t e s t . Chapters IV through VI present and d i s c u s s the f i n d i n g s . Chapter IV w i l l present three p e r s p e c t i v e s of the concepts of heat and temperature: s c i e n t i s t s ' s c i e n c e , school s c i e n c e and c h i l d r e n ' s s c i e n c e . The ideas and b e l i e f s expressed by the students i n the c l a s s w i l l be presented and those t o p i c s which provided the g r e a t e s t d i f f i c u l t i e s w i l l be i d e n t i f i e d . Chapter V w i l l focus on the students and on l e a r n i n g . Three measures of l e a r n i n g w i l l be compared in an attempt to i d e n t i f y f a c t o r s that might be r e l a t e d to l e a r n i n g . The success or l a c k of success students experienced i n l e a r n i n g the v a r i o u s concepts w i l l be c o n s i d e r e d . The next chapter w i l l examine i n s t r u c t i o n i n an 51 attempt to shed f u r t h e r l i g h t on the d i f f i c u l t i e s t h a t students experienced with some of the heat and temperature concepts. 52 CHAPTER IV PERSPECTIVES OF HEAT AND TEMPERATURE 4.0. Introduct ion If a cup of b o i l i n g water i s l e f t s i t t i n g at room temperature.for two or three hours, the temperature of the water w i l l drop to that of the room. Two hundred years ago i t would have been s a i d that the water had l o s t some " c a l o r i c . " Today many people would say i t had l o s t some "heat," without g i v i n g much thought to the c o r r e c t meaning of the term "heat." Our everyday language s t i l l suggests that heat and c o l d are substances which move from h o t t e r matter to c o l d e r matter, or v i c e v e r s a . In the winter we speak of keeping the heat i n a house or keeping the c o l d out. We keep a r e f r i g e r a t o r door shut to prevent c o l d from escaping. Few of us are i n s p i r e d to ponder the r e a l nature of heat or- of c o l d . , As the w r i t e r worked on t h i s d i s s e r t a t i o n , - many people f r e q u e n t l y asked about the sub j e c t of the r e s e a r c h . When t o l d i t i n v o l v e d ideas about the d i s t i n c t i o n between heat and temperature, many of the q u e s t i o n e r s were p u z z l e d . I t i s o f t e n assumed that temperature i s a measure of heat. With the excep t i o n of those with s c i e n c e backgrounds, none understood the d i s t i n c t i o n u n t i l presented with the f o l l o w i n g i l l u s t r a t i o n : 53 Three i d e n t i c a l saucepans are p l a c e d on three i d e n t i c a l burners of a stove. One pan c o n t a i n s two l i t r e s of water, another c o n t a i n s two l i t r e s of cooking o i l , and the t h i r d c o n t a i n s f i v e l i t r e s of water. A l l of the l i q u i d s are at room temperature. The burners are turned on f o r f i v e minutes and then the temperature of each l i q u i d i s recorded. W i l l a l l of the l i q u i d s be at the same temperature? If not, which w i l l be h o t t e s t ? C o o l e s t ? Why? Everyone p r e d i c t e d that the o i l would be h o t t e s t , and that the f i v e l i t r e s of water would be c o o l e s t . They then recognized that the amount and the kind of substance, as w e l l as the amount of heat energy, i n f l u e n c e the temperature change. T h i s i l l u s t r a t i o n makes i t meaningful to say that the temperature of matter depends not only on heat, but a l s o on the mass of the matter or o b j e c t , and on the kind of substance being heated. The idea that temperature i s a measure of heat i s not the only l a y view of heat that d i f f e r s from the view of today's p h y s i c i s t . T h i s chapter w i l l examine t h i s and many other a l t e r n a t i v e b e l i e f s about matter, heat and temperature. Three views or p e r s p e c t i v e s of heat and temperature w i l l be d e s c r i b e d . They i n c l u d e the p e r s p e c t i v e s of s c i e n t i s t s ' , of school s c i e n c e , and of the students. A glimpse at the s c i e n t i s t s ' p e r s p e c t i v e w i l l b r i e f l y d i s t i n g u i s h the concepts of heat, thermal (heat) energy and temperature, and compare these to the school s c i e n c e d e f i n i t i o n s . School s c i e n c e w i l l be examined i n more d e t a i l . The school s c i e n c e view has much i n common with s c i e n t i s t s ' s c i e n c e , although each has i t s own unique f e a t u r e s . School s c i e n c e attempts to make the concept of heat, as a form of energy, r a t h e r than a f l u i d , understandable to the average grade nine student. The g o a l s , content and the a c t i v i t i e s p r o v i d e d i n 54 t h e c u r r i c u l u m a n d t h e t e x t b o o k c h a p t e r s d e a l i n g w i t h h e a t a n d t e m p e r a t u r e w i l l be p r e s e n t e d . The m a j o r p o r t i o n o f t h e c h a p t e r w i l l i d e n t i f y and e x a m i n e t h e v a r i o u s i d e a s a nd b e l i e f s e x p r e s s e d by t h e s t u d e n t s - - t h a t i s , c h i l d r e n ' s s c i e n c e . The s e c t i o n on c h i l d r e n ' s s c i e n c e i n t r o d u c e s t h e c o m p l e x m i x o f t h e many a n d v a r i e d i d e a s e x p r e s s e d by t h e s t u d e n t s i n t h i s c l a s s . Some o f t h e i r b e l i e f s w ere r e l a t i v e l y s o p h i s t i c a t e d , w h i l e o t h e r s were v e r y n a i v e . M o s t o f t h e i d e a s c h a r a c t e r i z i n g s c h o o l s c i e n c e a n d s c i e n t i s t s ' s c i e n c e were a l s o e x p r e s s e d by one o r more s t u d e n t s . However, p r i o r t o i n s t r u c t i o n , e v e n t h e most s u c c e s s f u l s t u d e n t s r e v e a l e d c o n f u s i o n a b o u t b a s i c a s p e c t s o f h e a t and t e m p e r a t u r e phenomena. Most o f t h e a l t e r n a t i v e b e l i e f s e x p r e s s e d by t h e s t u d e n t s were a d d r e s s e d a s t h e u n i t was t a u g h t , a nd some o f t h e s t u d e n t s d i d e x p r e s s b e l i e f s on t h e p o s t t e s t t h a t were more c o n s i s t e n t w i t h s c h o o l Science, t h a n t h e i r p r e t e s t b e l i e f s . However, a number of a l t e r n a t i v e b e l i e f s p e r s i s t e d t h r o u g h o u t t h e u n i t a n d were e x p r e s s e d on t h e u n i t a n d / o r p o s t t e s t . M o r e o v e r , some a l t e r n a t i v e b e l i e f s were e x p r e s s e d on t h e p o s t t e s t t h a t h a d n o t been s t a t e d on t h e p r e t e s t ( a s s u g g e s t e d by O s b o r n e and W i t t r o c k , 1 9 8 3 ) . A l t e r n a t i v e b e l i e f s w h i c h were s t i l l p r e s e n t a t t h e end o f t h e u n i t a n d were e x p r e s s e d on e i t h e r t h e u n i t t e s t o r t h e p o s t t e s t were c a l l e d " p e r s i s t e n t " a l t e r n a t i v e b e l i e f s . T h a t i s , t h e y p e r s i s t e d i n s p i t e o f i n s t r u c t i o n . C h a p t e r V w i l l l o o k a t t h e s u c c e s s a n d / o r l a c k o f s u c c e s s s t u d e n t s e x p e r i e n c e d i n l e a r n i n g t h e h e a t and t e m p e r a t u r e c o n c e p t s . I n t h a t c o n t e x t , t h e p e r s i s t e n t a l t e r n a t i v e b e l i e f s w i l l be e x a m i n e d , a n d some p o s s i b l e r e a s o n s f o r t h e i r 55 persistence w i l l be explored. 4.1. Analysing the Data An understanding of the pa r t i c u l a t e nature of- matter i s essential to an understanding of the concepts of heat and temperature as presented, as students were expected to explain their observations and ideas in terms of p a r t i c l e behaviour. For this reason, that topic was included in the study and was i d e n t i f i e d as the f i r s t of the major topics. The science content covered during the study i s presented in three chapters of the textbook (chapters seven to nine). Based on the organization of the text and the essential learning outcomes prescribed by the curriculum guide, the investigator organized that content into four major topics: heat energy and i t s e f f e c t s on matter, temperature and how i t i s measured, the d i s t i n c t i o n between heat and temperature, and heat transfer. With the inclusion of the particulate nature of matter, t h i s resulted in a t o t a l of f i v e major topics. 4.1.1. S c i e n t i s t s ' Science The primary data source for the s c i e n t i f i c d e f i n i t i o n s of heat, thermal energy and temperature, and related concepts, was a commonly used college introductory physics textbook (Giancoli, 1980) . 56 4.1.2. School Science In B r i t i s h Columbia, the junior secondary science curriculum i s prescribed by the Ministry of Education. Therefore, a l l schools in the province are required to use the same textbook for grade nine science. Relevant sections of the curriculum guide (Curriculum Development Branch, 1979, hereafter referred to as "the curriculum guide"), the textbook (Schmid and Murphy, 1979, hereafter referred to as "the textbook") and the teachers' guide (Schmid et a l . , 1980, hereafter referred to as "the teachers' guide") and interviews with the teacher provided the data for thi s section. The relevant sections of each source were c a r e f u l l y examined for several types of information. The following questions guided the examination: 1. What are the ov e r a l l goals for grade nine science? 2. What i s the rationale for including the unit in the program? 3. What are the s p e c i f i c goals and objectives for the heat and temperature unit? 4. What content i s prescribed? How is i t sequenced? 5. What assistance do the various sources provide to al e r t teachers to potential d i f f i c u l t i e s students may experience? 6. To what extent does the textbook take account of known d i f f i c u l t i e s when presenting the more complex concepts to the students? 4.1.3. Children's Science The ideas and b e l i e f s expressed by the students have been organized according to the major curriculum topics. As an understanding of the par t i c u l a t e nature of matter is a 57 prerequisite to understanding the concepts of heat energy as presented in t h i s unit, i t has also been considered in t h i s study, and appears as the f i r s t major topic. Each idea was examined in terms of three c r i t e r i a : 1. i t s consistency with the school science perspective, 2. how many students expressed the idea, and 3. the persistence of the idea (this w i l l be p a r t i c u l a r l y relevant for alternative b e l i e f s ) . From th i s examination ten persistent alternative b e l i e f s have been i d e n t i f i e d . . Several steps were involved in identifying the students' ideas and b e l i e f s about heat and temperature. The f i r s t step was the preparation of the conceptual biographies. Each conceptual biography consisted of a detailed decription and analysis of the ideas and b e l i e f s of one target student. The introduction to each biography provided general information on the student, including the teacher's view of the student's a b i l i t y and work habits, and the investigator's comments on the behaviour and work habits demonstrated during the heat and temperature unit. The pretest and posttest responses of the target students were also c a r e f u l l y examined. A l l of the ideas were organized according to the f i v e major topics i d e n t i f i e d above. The student's pretest interview, assignments and laboratory reports, and contributions to class discussions were also examined and categorized under the five topics. Based on these data, a description was prepared, presenting the student's prior b e l i e f s , analysing the changes which occurred in those b e l i e f s during the unit and concluding with the student's 58 b e l i e f s as expressed on the unit test and the posttest. These descriptions of the student's b e l i e f s constituted the major portion of each biography and emphasized the contrast between the pretest and posttest b e l i e f s of the student. The analysis stressed accounting for changes in b e l i e f s wherever possible (Appendix D ) . The next l e v e l of analysis consisted of a compilation of a l l of the ideas and b e l i e f s expressed by a l l 23 students in the cl a s s . A l l of the pretests, posttests, unit tests, transcripts of class discussions and written laboratory reports and other assignments were examined for a l l students. A l l of the ideas were again categorized under the major topic headings. The textbook and curriculum guide were also examined to ensure that a l l of the ideas presented in "school science" were included. After the complete range of ideas and b e l i e f s had been i d e n t i f i e d , a brief description was prepared for each idea. The descriptions indicated the extent to which each idea was expressed by the students and included quotations from the various data sources to i l l u s t r a t e the range of ideas expressed. These descriptions are presented i n . section 4.4.2, and constitute the major portion of th i s chapter. 4.2. The S c i e n t i s t s ' Perspective: S c i e n t i s t s ' Science This rather brief section i s included to indicate the extent to which the concept of heat has been modified for presentation to grade nine students. The term "heat energy" in the textbook (Schmid and Murphy, 1979) includes the two d i s t i n c t concepts of "heat" and "i n t e r n a l energy" (sometimes referred to 59 as heat energy or thermal energy) recognized in modern science. This terminology i s in contrast to that in a college level physics textbook used in B r i t i s h Columbia (Giancoli, 1980), where the following d i s t i n c t i o n is made between temperature, heat and internal energy: Using the kinetic theory, we , can now make a clear d i s t i n c t i o n between temperature, heat, and internal energy. Temperature i s a measure of the average kinetic energy of individual molecules. Thermal o_r internal energy refers to the t o t a l energy of a l l the molecules in the object. ... Heat, f i n a l l y , refers to a transfer of energy (usually thermal energy) from one object to a second which i s at a lower temperature. Heat, as Count Rumford saw, can be generated i n d e f i n i t e l y , but the thermal energy of a body i s s t r i c t l y l i m i t e d . (Giancoli, 1980, p. 228-229). These d e f i n i t i o n s are more consistent with s c i e n t i s t s ' science than with those provided in the grade nine textbook. 4.3. The Curriculum Perspective: School Science . A major revision of the Science 9 program was completed in 1979, and included the production of a new textbook. In July of that year a decision was made, based on the results of the 1978 Science Assessment (Hobbs et a l . , 1979), to completely revise the Junior Secondary Science Program (grades 8, 9 and 10) in B r i t i s h Columbia. Thus, the newly revised 1979 curriculum was i d e n t i f i e d as a "preliminary" guide and intended to be in effect only u n t i l the new program could be developed and implemented, expected to be in September, 1981. A revised curriculum for grades eight through ten was published in 1983. Preparation of new textbooks was underway. Because the existing grade nine textbook had been so recently revised, the grades ten and eight books were given p r i o r i t y . At the present time (1985/86 school year), the new grade eight and ten books are in use, but the new 60 grade nine textbook i s not yet ava i l a b l e . In the revised program the study of heat and temperature has been moved to grade eight. In the 1979 grade nine program, four broad f i e l d s of science are examined: physics, space science, chemistry and biology. Energy provides the theme for the entire text, and teachers are urged, both in the text i t s e l f and in the teachers' guide, to study the energy (physical science) unit f i r s t . In the curriculum guide, the following physical science topics are identi f ied: ...what energy i s , present and future sources of energy; kinds of energy (some po t e n t i a l , some k i n e t i c ) ; how each kind can be transformed to other kinds; how f r i c t i o n transforms kinetic energy to heat energy; how forces are involved in transformations of energy; how simple machines can change the force necessary to transform energy; what energy converters are used in everyday l i f e ; what we mean by the power of an energy converter; how we measure temperature; how heat energy and temperature are involved in phase changes; how temperature can be used to measure heat energy; how heat energy i s transferred and how useful energy can be saved. (Curriculum Development Branch, 1979, p. 8) . The l a s t five of these are the subject of th i s study. 4.3.1. Goals and Objectives of the Unit The curriculum developers recognized that few teachers have specialized t r a i n i n g in a l l branches of science, and hence have provided not only a comprehensive rationale and program goals, but also detailed learning outcomes for the program. The teachers' guide states: The basic aim of [the energy] unit i s to enable students to understand energy s u f f i c i e n t l y for them to make wise decisions about the use of energy in the future and the conservation of energy in the present. (Schmid et a l . , 1980, p. 1) The learning outcomes for this unit have been i d e n t i f i e d as 61 either "essential" (Table 4.1) or "optional" (Table 4.2). It was recommended that a minimum of 100 hours be provided for the entire Science 9 course. Table 4.1 Essential Learning Outcomes Grade Nine Science (1979) Describe the steps by which various forms of energy are eventually transformed into heat energy. Recognize kinetic energy of p a r t i c l e s as heat energy. Describe and read a l i q u i d - i n - g l a s s thermometer. Distinguish between the heat energy of an object (the t o t a l energy of a l l i t s p a r t i c l e s ) and i t s temperature (which depends on the average kinetic energy per p a r t i c l e ) . Recognize that when two bodies of di f f e r e n t temperatures are in contact, heat energy i s conducted from the hotter to the cooler u n t i l both bodies reach the same temperature. Understand that the conduct ion of heat i s in terms of p a r t i c l e s . Observe that metals are good conductors and a i r a good insulator. Describe convection as a means of transferring heat energy. Recognize from observations that objects that radiate infra-red rays w i l l lose heat energy. Infer from observations that d u l l , dark objects absorb infra-red radiation best, while l i g h t , shiny objects r e f l e c t i t best. Describe the insulation in a house and how i t slows down the transfer of heat energy by conduction, convection and radiat ion. Discuss the use of present and future energy sources, considering environmental e f f e c t s , p r a c t i c a l ways of using less energy and safety considerations. Table 4.2 Optional Learning Outcomes Grade Nine Science (1979) 62 Describe some other thermometers and their uses. Explain how, during a phase change, the heat energy of water can change without i t s temperature changing. Compare the amount of heat energy necessary to: 1) melt a given amount of water, 2) bring the same amount of water to the b o i l i n g point and 3) change this water to steam. Recognize that the b o i l i n g temperature of water can be increased and the freezing temperature decreased by increasing the pressure on the water. Understand and define s p e c i f i c heat. Calculate the amount of energy necessary to raise the temperature of a given mass of material a given amount. Calculate the f i n a l temperature when given masses of similar materials are mixed. Recognize that heat energy i s conducted from one body to another faster when the temperature difference between them is greater. Recognize that a hot f l u i d w i l l f l o a t on a colder amount of the same f l u i d . Understand that higher temperature objects lose heat energy by radiation faster than objects of lower temperature. The curriculum guide i d e n t i f i e s learning outcomes from the a f f e c t i v e and psychomotor domains, as well as the cognitive. It is ' pointed out that although the last two of these are more ea s i l y achieved, the a f f e c t i v e domain must not be overlooked. Af f e c t i v e content is d i f f i c u l t to is o l a t e and tends to be a result of successfully teaching the other two domains. It includes the following l e v e l s : receiving, responding, valuing, organization and characterization, with each of these further divided in r e l a t i o n to the students' awareness, willingness, 63 acceptance and extent of implementation or action. The curriculum guide also provides suggestions for teaching the course, including the use of the laboratory, selected science readings, suggested evaluation techniques and recommended audio-visual and print resources. 4.3.2. The Content of the Unit Temperature and heat energy are the focus of the present study and a l i s t of the topics examined in the three textbook chapters dealing with heat energy and temperature i s provided in Table 4.3. The balance of thi s section w i l l b r i e f l y review the content and rationale of these three chapters as' presented in the textbook and the teachers' guide. In "addition, any comments in the teachers' guide that refer to common misunderstandings or to d i f f i c u l t i e s experienced by students w i l l be i d e n t i f i e d and summarized. The stated rationale for the chapter on heat energy i s to make certain the students understand the meaning of temperature, at this point "best defined as a reading on a thermometer" (Schmid et a l . , 1980, p. 98) and to introduce the concept of heat energy. This use of an operational d e f i n i t i o n ignores the actual meaning of the term, "temperature." The chapter begins by defining heat energy as follows: "The heat energy that any object has i s the mechanical energy of a l l i t s p a r t i c l e s added up." (Schmid and Murphy, 1979, p. 101 ). A narrative section explains that heat energy i s produced in a l l energy transformations and students do an investigation in which a chaos machine serves as a model to dis t i n g u i s h the mechanical 64 Table 4.3 Contents of Chapters 7, 8 and 9 Chapter 7. Heat Energy 1.34 Heat energy and energy transformations 1.35 Investigation: Heat engine 1.36 The energy of p a r t i c l e s 1.37 Investigation: Measuring temperature with a mercury thermometer 1.38 Investigation: Measuring temperature by expanding so l i d s (demonstrat ion) 1.39 Investigation: Absolute zero o 1.40. Thermometers 1.41 Review Chapter 8. The Difference Between Temperature and Heat Energy 1.42 Investigation: The heat energy- and temperature of di f f e r e n t objects 1.43 Heat energy and temperature 1.44 Differences in s p e c i f i c heat 1.45 Investigation: Heat energy and temperature in phase changes 1.46 Review Chapter 9. The Transfer of Heat Energy 1.47 What happens to heat energy 1.48 Investigation: Conduction 1.49 Investigation: Convection 1.50 Investigation: Radiation of infra-red rays 1.51 What happens when energy i s transferred 1.52 Infra-red radiation 1.53 Insulation 1.54 Review 65 energy of the individual p a r t i c l e s from the c o l l e c t i v e energy (heat energy) of a l l of the p a r t i c l e s . The teachers' guide points out that students tend to think of heat energy as a f l u i d that i s added to or removed from an object, and teachers are advised to stress the idea that heat energy i s the energy of the p a r t i c l e s . However, the textbook does not use th i s approach ( i . e . , i t does not acknowledge the p o s s i b i l i t y that students may have th i s alternative b e l i e f and point out how that belief i s inconsistent with school science). The guide also states: The statement that gas p a r t i c l e s have nothing smaller to give their energy to i s a s i m p l i f i c a t i o n of the facts. Thinking students may know that many p a r t i c l e s are made of atoms which, in fact-, are made of smaller p a r t i c l e s s t i l l . ... However, because the number of component parts of a p a r t i c l e i s small (compared to the number of component p a r t i c l e s of a macroscopic object) energy can be given back by the component parts to the p a r t i c l e as a whole. In contrast, the chance of energy being given back to a large object by i t s p a r t i c l e s is p r a c t i c a l l y n i l . (Schmid et a l . , 1980, p. 106) Such an explanation could confuse teachers as well as students, as i t i s incorrect from the s c i e n t i s t s ' science perspective. Celsius and Kelvin temperature scales are introduced. Using a mercury thermometer, students measure temperature and learn how a thermometer i s ca l i b r a t e d . They learn that the mercury thermometer depends on the property of thermal expansion. The kinetic model of thermal expansion is given a great deal of emphasis. Students are told that when matter i s heated i t s p a r t i c l e s gain mechanical energy and h i t each other harder and that the spaces between the p a r t i c l e s become larger. They are asked to explain why: "a) l i q u i d s expand when the temperature goes up; b) l i q u i d s contract when the temperature goes down" (Schmid and Murphy, 1979, p. 110). The teachers' 66 guide suggested answers are: a) that the mechanical energy of the p a r t i c l e s increases so the p a r t i c l e s h i t each other harder and move farther apart; and b) the p a r t i c l e s lose mechanical energy, do not h i t each other as hard and "the forces of at t r a c t i o n between them, p u l l them closer together" (Schmid et a l . , 1980, p. 109). Next, the bimetallic s t r i p i s demonstrated and i t s uses as a thermometer are described. Students are asked what happens when a s o l i d object i s heated: a) to the size of i t s p a r t i c l e s ; b) to the mechanical energy of i t s p a r t i c l e s ; and c) to the spaces between the p a r t i c l e s (Schmid and Murphy, 1979, p. 112). The idea that, the spaces, not the p a r t i c l e s , are responsible for the expansion i s stressed. A question at the end of the chapter asks what happens to the spaces between the p a r t i c l e s of a i r when a i r i s heated and how t h i s a f f e c t s the density of a i r . An optional investigation uses a gas-* thermometer to extrapolate the value of absolute zero. The concept of absolute zero i s intended to help develop some understanding of the amount of heat energy in matter at normal temperatures. The aim of chapter eight i s to c l a r i f y the d i s t i n c t i o n between temperature and heat energy. Three controlled calorimetry experiments demonstrate that an increase in the temperature of matter depends not only on heat energy, but also on the mass and the kind of material being heated. The teachers' guide advises stressing the idea that these experiments are controlled, and recommends having students id e n t i f y the constants and the variables. The three experiments include comparisons of the temperature change that occurs when 67 the following are placed in water: equal masses of a metal at dif f e r e n t i n i t i a l temperatures; d i f f e r e n t masses of the same metal at the same i n i t i a l temperature; and, equal masses of two dif f e r e n t metals at the same i n i t i a l temperature. A reading section provides an explanation of the difference in heat energy and temperature in terms of p a r t i c l e s . Students are told that p a r t i c l e s have mechanical energy and that matter has heat energy. They are to l d that the temperature of mercury "depends on how much mechanical energy each mercury p a r t i c l e has, on the average" (Schmid and Murphy, 1979, p. 132). Heat energy, on the other hand, depends not only on how much energy each p a r t i c l e has, but also on how many p a r t i c l e s there are. That i s , heat energy i s "the t o t a l energy of a l l i t s p a r t i c l e s added up" (Schmid and Murphy, 1979, p. 132). In the next investigation, students observe that when ice is heated u n t i l i t melts and then b o i l s , the rate of temperature change is not constant across phase changes. Because the water-ice mixture cannot be in a state of true equilibrium while being heated by a bunsen burner, the teachers' guide cautions that the temperature w i l l be seen to r i s e s l i g h t l y while the ice i s melting and suggests that the students should s t i r the mixture constantly as long as ice remains in the beaker. In spite of this l i m i t a t i o n , students observe that the temperature ri s e s much more rapidly after the ice has melted and that i t remains constant once b o i l i n g begins. The guide also warns that students should not think that the temperature of water vapour cannot exceed 100°C. The importance of these warnings w i l l become evident as the findings of thi s study are presented in later chapters. 68 The t h i r d and f i n a l textbook chapter to be considered examines the transfer of heat energy. It i s stressed in the teachers' guide "that differences in temperature cause the transfer of heat energy" (Schmid et a l . , 1980, p. 133). The chapter begins by explaining "heat transfer" and considers both desirable and undesirable examples of heat transfer. Conduction, convection and radiation are examined macroscopically and conduction i s described at the p a r t i c l e l e v e l . The chapter concludes with a discussion of conservation of heat energy in the home. Throughout the chapter, frequent reference i s made to everyday examples of heat transfer. An investigation of conduction shows that heat energy i s transferred from hotter matter to colder matter and that the rate at which heat energy i s transferred varies for di f f e r e n t materials. For example, metals conduct heat energy much faster than non-metals.' Very poor conductors are c a l l e d insulators. In the questions, students are required to explain conduction in terms of p a r t i c l e motion, and i t is pointed out that metals feel colder than non-metals because they are good conductors. Next, students observe convection currents and learn that when a f l u i d i s heated, i t s density decreases and i t r i s e s . The investigation and the questions deal with convection in both gases and l i q u i d s , but do not ask for explanations in terms of p a r t i c l e s . Infra-red radiation is observed and then students investigate factors a f f e c t i n g absorption, r e f l e c t i o n and radiation of infra-red r a d i a t i o n . A discussion section concludes the chapter by reviewing the ideas presented in the chapter. The eff e c t s of conduction, 69 convection and radiation are considered, with p a r t i c u l a r emphasis on the greenhouse effect and home insul a t i o n . The physics portion of the text concludes with chapter ten, "How our use of energy affects our world." In the introductory section, students are t o l d that t h i s chapter i s more related to their d a i l y l i v e s and that the previous chapters have provided them with an understanding of energy that w i l l allow them to "be better able to understand the very important material in t h i s chapter" (Schmid and Murphy, 1979, p. 173). The chapter i s summarized as follows: F i r s t you w i l l look back in time to see how our present world came to be. Then, you w i l l read about the many ways in which we use energy and the kinds of energy sources we are using. (Possible future sources of energy are also mentioned.) F i n a l l y , you w i l l find out what things you can do to help make the future a good time to l i v e i n . (Schmid and Murphy, 1979, p. 173) 4.3.3. Teaching the Unit The teachers' guide recommends that 13 class hours be provided for chapters seven to nine, with half of that time being devoted to laboratory investigations. In the class p a r t i c i p a t i n g in the study, nine one-hour periods were provided for the three chapters. Chapter ten was omitted due to lack of time (the end of term was two weeks away and the biology unit had not yet been taught). A l l students performed investigations two periods, and during a t h i r d period one group of students performed a demonstration investigation. The teacher also performed demonstrations on two occasions. A tenth day was devoted to the teacher-made unit test and the investigator's posttest. The instruction provided in the unit i s the subject of Chapter VI and w i l l be examined in d e t a i l then. 70 4 . 4 . The Students' Perspectives: Children's Science Prior to instruction ( i . e . , on the pretest and/or during the interview), none of the students expressed an accurate understanding of the d i s t i n c t i o n between heat and temperature. Even Alan, whose pretest responses were c l e a r l y closer to the school science perspective than those of any other student, spoke of heat and temperature as i f temperature were a measure of heat. Although almost a l l of the students gave acceptable (to the teacher) d e f i n i t i o n s of the two terms on the unit test, few revealed a clear understanding of the school science perspective on the posttest. This was to be the case for many of the concepts presented in t h i s unit, as was evident from the many alternative b e l i e f s which persisted, at the end of the unit. Three fundamental d i s t i n c t i o n s appear to l i e at the heart of most of the d i f f i c u l t i e s experienced by students. In almost every case, the problems' appeared to be related to a f a i l u r e to understand one of the following d i s t i n c t i o n s : 1 . Matter consists not only of p a r t i c l e s , but also includes the space between the p a r t i c l e s . While the distance between p a r t i c l e s can vary, the size of the p a r t i c l e s remains constant. 2. There is a d i s t i n c t i o n between the macroscopic behaviour of matter and the sub-microscopic behaviour of the p a r t i c l e s which comprise the matter. For example, when matter i s heated i t expands. The p a r t i c l e s do not expand. 3. The temperature of matter depends on the average mechanical energy of i t s p a r t i c l e s , whereas the amount of heat energy ( i . e . , internal energy) in matter depends on the t o t a l 71 mechanical energy of the p a r t i c l e s . As a l l of the students in the class completed both the pretest and the posttest, these provided a major source of the data. Most of the many alte r n a t i v e b e l i e f s i d e n t i f i e d on the pretest and/or during interviews were again expressed in the class discussions or in the written assignments completed by the students. A l l written work was-handed in and examined by the investigator, who pointed out errors to the students by either writing in the correct answer or, in the case of more complex errors or misunderstandings, d i r e c t i n g the student to discuss the question with the teacher or the investigator. Only one student, Alan, ever consulted the investigator on his own i n i t i a t i v e . This section w i l l summarize the range of ideas and b e l i e f s expressed by the students during the study. P a r t i c u l a r attention w i l l be paid to the target students to i l l u s t r a t e the range of perspectives. 4.4.1. Di s t i n c t i o n s Which Led to Student D i f f i c u l t i e s The three d i s t i n c t i o n s described above caused d i f f i c u l t i e s in a variety of contexts. This section w i l l introduce some of the problems which arose, and provide some s p e c i f i c examples of ideas which proved to be d i f f i c u l t for the students. Matter: P a r t i c l e s and Spaces A l l of the students e a s i l y spoke of matter being composed of p a r t i c l e s . The problems appeared when they had to deal with the spaces between the p a r t i c l e s . Some students believed that the "matter" included only the actual p a r t i c l e s , not the spac£S between the p a r t i c l e s . This b e l i e f should not be surprising, as 72 we do often define "space" as the absence of matter. Students recognized that p a r t i c l e s are in constant motion and that they are farther apart in gases than in l i q u i d s , and in li q u i d s than in s o l i d s . Some of the students indicated they believed that when heat i s transferred i t moves through the spaces between the p a r t i c l e s . For example, one student indicated that heat i s transferred through glass by " a i r p a r t i c l e s , " apparently thinking the spaces contained a i r . Some of the students suggested that less dense matter i s a better conductor of heat than more dense matter because i t has larger spaces for the heat to move through. The Behaviour of P a r t i c l e s and Matter The students seemed to assume that because a p a r t i c l e is a very small piece of matter, that the c h a r a c t e r i s t i c s or properties of the material also characterize the p a r t i c l e s . B e l i e f s expressed by Cathy (Jane's partner) provide a good i l l u s t r a t i o n of the d i f f i c u l t i e s that may arise i f th i s d i s t i n c t i o n i s not made. For example, Cathy said that ice melts because the p a r t i c l e s become warmer and melt, and that warm a i r rise s because the p a r t i c l e s become l i g h t e r . Thus, she was attempting to explain the macroscopic properties of matter by at t r i b u t i n g those same properties to the p a r t i c l e s making up that matter. Cathy c l e a r l y did not understand the d i s t i n c t i o n between the behaviour of p a r t i c l e s at the microscopic or molecular l e v e l , and the behaviour of matter at the macroscopic l e v e l . Other properties that students attributed to p a r t i c l e s included: the a b i l i t y to get hotter, expand and contract, dissolve, evaporate, and become heavier. These ideas are 73 inconsistent with the kinetic theory of matter, and students who expressed any of these ideas revealed a lack of understanding of that theory. The theory may have been i n t e l l i g i b l e , or even plausible to them, but i t was c e r t a i n l y not f r u i t f u l . Heat and Temperature The t h i r d and f i n a l fundamental d i s t i n c t i o n deals with heat and temperature. The teacher i d e n t i f i e d t h i s d i s t i n c t i o n as the most d i f f i c u l t idea in the unit. The textbook d e f i n i t i o n s of the terms are complex and deal with the mechanical energy of the p a r t i c l e s . Heat i s the t o t a l mechanical energy; temperature i s the average mechanical energy. For most of the students, these d e f i n i t i o n s were not even i n t e l l i g i b l e . Recognizing the d i f f i c u l t y , the textbook and the teacher advised that "hotness or coldness" would be an acceptable d e f i n i t i o n of temperature. This idea was easier to understand, but i t may have led to some other d i f f i c u l t i e s . For example, on the posttest, some very able students indicated they believed that heat and cold were di f f e r e n t thermal e n t i t i e s . Another alternative belief which may be related to t h i s d e f i n i t i o n was expressed when the students observed that a metal faucet f e l t colder than a wooden table top, and concluded that they were at diff e r e n t temperatures. As the heat and temperature d i s t i n c t i o n i s a key concept in the unit, i t w i l l be the focus of much of t h i s study. 4.4.2. Students' Ideas and Be l i e f s This section w i l l present the range of student b e l i e f s about the par t i c u l a t e nature of matter and about heat and temperature. 74 Topic A: The Particulate Nature of Matter The students had already completed the chemistry unit before beginning heat and temperature. In the chemistry section, the textbook notes that students had examined the p a r t i c l e model in grade eight science. The chemistry unit i s based on the p a r t i c l e model, and the following brief segment from the text reviews the important features of the model: In your l a s t science course, you used the p a r t i c l e model of matter. According to t h i s model, a l l materials are c o l l e c t i o n s of very tiny p a r t i c l e s that are always moving as shown in F i g . 3. The p a r t i c l e s of a material -stay together because they a t t r a c t each other. They have spaces between them because they are always moving in a l l d i r e c t i o n s . The space between the p a r t i c l e s contains nothing; i t is a perfect vacuum. (Schmid and Murphy, 1979, pp. 350 and 352) This description can be broken down into three ideas, each of which posed p a r t i c u l a r problems for the students. Idea A.1: A l l matter i s composed of p a r t i c l e s . None of the students expressed any doubt that matter is indeed composed of tiny p a r t i c l e s . Prior to the unit some of the students used the terms "atoms" and "molecules", rather than " p a r t i c l e s . " By the end of the unit only one student persisted in r e f e r r i n g to "molecules" rather than " p a r t i c l e s . " On the pretest nine students referred to either p a r t i c l e s , atoms or molecules at least once. These nine, plus an additional ten, students did so on the posttest. Four students did not mention p a r t i c l e s (or atoms or molecules) on either the pretest or the posttest. Throughout the text, " p a r t i c l e s " are referred to when matter i s discussed. In c l a s s , the teacher referred to 75 p a r t i c l e s d a i l y . Frequently when a student was asked to explain a phenomenon he or she would answer on a macroscopic l e v e l , and the teacher would say, "Talk to me about p a r t i c l e s , " or "Explain i t in terms of p a r t i c l e s . " Thus, the students were continually being bombarded by p a r t i c l e s , f i g u r a t i v e l y as well as l i t e r a l l y . We have already noted that in spite of the teacher's urging, some students did not dis t i n g u i s h between the properties or behaviour of matter and the properties or behaviour of the p a r t i c l e s . In addition, some students believed that "matter" did not include the spaces between the p a r t i c l e s , but only the p a r t i c l e s themselves. For example, on the posttest Cathy wrote that when heated, "water looks as i f i t expands. Actually only the spaces are." Cathy c l e a r l y did not have a good understanding of the kinetic theory of matter. SUMMARY: Prior to the unit none of the students revealed any doubt that matter i s composed of p a r t i c l e s . However, many revealed they did not have a good understanding of the kinetic theory of matter. The theory was i n t e l l i g i b l e , but not plausible for them. Idea A.2: The p a r t i c l e s of matter are in constant motion and therefore have mechanical energy. None of the students mentioned mechanical energy on the pretest. Jane and six others referred to i t on the posttest. There was some confusion about the d i s t i n c t i o n between mechanical energy (of the p a r t i c l e s ) and heat energy (the t o t a l mechanical energy of an object or of a defined unit of matter). For example, one boy spoke of p a r t i c l e s "heating up" on the 76 pretest. On the posttest three other students expressed the be l i e f that p a r t i c l e s have heat energy. One of these, a g i r l , also referred to mechanical energy in reference to p a r t i c l e s . Another g i r l spoke of p a r t i c l e s being heated, and Brian referred to the heat energy of p a r t i c l e s . In a laboratory report, Cathy wrote that in a s o l i d the p a r t i c l e s stopped moving and therefore there were no spaces. These d i f f i c u l t i e s are related to two of the d i f f i c u l t d i s t i n c t i o n s i d e n t i f i e d e a r l i e r . Students who do not understand the school science d i s t i n c t i o n between mechanical energy and heat energy in terms of p a r t i c l e s and their behaviour, w i l l not understand the school science view that i t is only matter, not p a r t i c l e s , that can "heat up," or the textbook d e f i n i t i o n s which distinguish temperature and heat energy on the basis of mechanical energy. SUMMARY: Students did not question the idea that p a r t i c l e s are in constant motion. Only one student suggested that t h i s i s not always the case. The precise nature of mechanical energy and i t s r elationship to heat energy were not well understood. To use the conceptual change terminology again, the concepts of heat energy and mechanical energy may have been plausible in their simplest form, but for many of the students, they were not f r u i t f u l . That i s , students appeared to believe that mechanical energy and heat energy existed, but the concepts did not have explanatory and predictive power for them. 77 Idea A.3: The spaces between the p a r t i c l e s are a perfect vacuum. Several students seemed confused about the nature of the spaces between the p a r t i c l e s . Alternative b e l i e f s were p a r t i c u l a r l y evident when students were trying to explain heat transfer and suggested that heat moved between the p a r t i c l e s . For example, on the pretest Jane said that when an ice cube melts heat gets into any cracks the ice has. It appears that she thought that cracks would be the only spaces between the p a r t i c l e s in ice and that heat only moves through spaces. On the pretest Carolyn predicted that glass would be a good conductor and that heat would get through a glass wall by " a i r p a r t i c l e s . " This suggests that Carolyn believed that'the spaces between the p a r t i c l e s contained a i r . Altogether, on the posttest six g i r l s spoke of heat moving through the spaces or through a i r spaces between the p a r t i c l e s . SUMMARY: The nature of the spaces between the p a r t i c l e s caused d i f f i c u l t y for some students. For most students, the existance of the spaces was an i n t e l l i g i b l e concept, but i t was not plausib l e . Topic B: Heat Energy and Its Effects on Matter A great variety of responses were produced when students were asked what happens to matter when i t is heated. This and other related questions were posed in several d i f f e r e n t and often ambiguous contexts and students frequently responded inappropriately. For example, during a discussion of thermal expansion, one demonstration involved heating a bimetallic s t r i p . When asked to predict what would happen to the metal 78 s t r i p some s t u d e n t s i n s i s t e d i t w o u l d m e l t . On o t h e r o c c a s i o n s when t h e t o p i c was t h e b e h a v i o u r o f t h e p a r t i c l e s o f m a t t e r b e i n g h e a t e d , s t u d e n t s r e p e a t e d l y r e s p o n d e d i n t e r m s o f what w o u l d be o b s e r v e d v i s u a l l y a n d m a c r o s c o p i c a l l y . T h i s s e c t i o n w i l l e x a m i n e s t u d e n t i d e a s a b o u t h e a t e n e r g y a n d i t s e f f e c t s on m a t t e r , b o t h a t t h e m a c r o s c o p i c a n d t h e p a r t i c l e l e v e l s . I d e a B.1: D e f i n i t i o n s o f H e a t E n e r g y A number o f s t u d e n t s e x p e r i e n c e d d i f f i c u l t y r e s o l v i n g t h e i d e a t h a t h e a t i s a f o r m o f e n e r g y , r a t h e r t h a n m a t t e r . T h i s s h o u l d n o t be s u r p r i s i n g , a s o u r e v e r y d a y l a n g u a g e r e f e r s t o h e a t a s i f i t i s i n d e e d a f o r m o f m a t t e r ( e . g . , i n w i n t e r we k e e p t h e d o o r s a n d windows c l o s e d t o k e e p t h e h e a t i n t h e h o u s e ) . T h r e e a l t e r n a t i v e b e l i e f s a b o u t t h e n a t u r e o f h e a t were e x p r e s s e d by s t u d e n t s : h e a t i s a f o r m o f m a t t e r a n d c o n s i s t s o f p a r t i c l e s ; h e a t i s s o m e t h i n g t h a t moves b e t w e e n t h e p a r t i c l e s o f m a t t e r ; h e a t i s s o m e t h i n g t h a t p u s h e s t h e p a r t i c l e s o f m a t t e r . E a c h o f t h e s e b e l i e f s h a s a s u b s t a n c e o r i e n t a t i o n . F o u r d i f f e r e n t i d e a s a b o u t t h e n a t u r e o f h e a t were i d e n t i f i e d . An a d d i t i o n a l a n d r e l a t e d i d e a was t h e b e l i e f t h a t c o l d a n d h e a t a r e two d i s t i n c t " t h i n g s . " T h i s i d e a i s a l s o e x a m i n e d i n t h i s s e c t i o n . B.1.1: The h e a t e n e r g y o f an o b j e c t o r o f m a t t e r i s t h e sum o f t h e m e c h a n i c a l e n e r g y o f t h e p a r t i c l e s i n t h e o b j e c t o r m a t t e r . T h i s t e x t b o o k d e f i n i t i o n was p r o v i d e d by 12 s t u d e n t s on t h e u n i t t e s t . A s t h e s t u d e n t s were n o t r e q u i r e d t o e x p l a i n t h e d e f i n i t i o n , i t i s n o t p o s s i b l e t o d e t e r m i n e how many s t u d e n t s u n d e r s t o o d i t s m e a n i n g . 79 B.1.2: Heat i s a form of matter and consists of p a r t i c l e s . Three students referred to heat p a r t i c l e s or molecules. Carolyn mentioned heat p a r t i c l e s three times during the pretest interview. F i r s t , when discussing heat being transferred from the hot n a i l to the water, again when explaining the transfer of heat through the metal rod ("the heat p a r t i c l e s are moving"), and f i n a l l y to explain the movement of a needle, which was actu a l l y moved due to a metal rod expanding as i t was heated. In the last instance, Carolyn said, "the heat p a r t i c l e s cause the needle and the pointer to move." S i m i l a r l y , in the interview Gordon said that when the hot n a i l was put in the water, "the water molecules h i t the heat substance and then somehow i t sucks i t in and changes." When asked where heat energy would go as the water cooled, Gordon replied, " . . . i t could just go, just evaporate, yeah, I guess, i t evaporates i f i t ' s steam." In a laboratory report, Susan also suggested that "heat turns to steam" when l i q u i d s are heated (Inv. 1.37). Gordon also spoke of a i r picking up heat molecules during the class discussion of conduction, and was corrected by the teacher who interjected, "heat energy transferred." On the posttest one other g i r l said that heat moves through a wall by "heat p a r t i c l e s . " A l l of these students used terminology which suggested they were thinking of heat, as a form of matter. Gordon and Susan both spoke of heat turning to steam, and Gordon made one reference to heat molecules. The other two g i r l s spoke of heat p a r t i c l e s on only one occasion each. As these ideas were not consistently expressed by any of these students, i t seems l i k e l y that they r e f l e c t e d confusion about the exact 80 mechanism of heat transfer, rather than an e x p l i c i t belief that heat is a form of matter. B.1.3: Heat is something that moves between the p a r t i c l e s of matter. Attempts to explain conduction sometimes involved references to heat moving through spaces or cracks. As noted e a r l i e r , Jane suggested that ice melts because heat gets in cracks in the ice. She also suggested that heat may move between water p a r t i c l e s on the pretest. Another g i r l referred to heat moving through " a i r holes" on the pretest and to heat moving through spaces on the posttest. Somewhat surprisi n g l y , six g i r l s spoke of heat moving through spaces or a i r spaces on the posttest, indicating that t h i s idea was more prevalent at the end of the unit than i t had been prior to the unit. For example, on the posttest Susan said that styrofoam would be a good conductor because i t was f u l l of holes and that heat travels better when p a r t i c l e s are farther apart. Another g i r l said that heat moves through the a i r spaces in a glass rod. On one of the assigned questions, Susan wrote that heat goes through a metal pan "because the p a r t i c l e s are farther apart." These six g i r l s obviously did not understand the school science explanation of conduction as the transfer of energy from p a r t i c l e to p a r t i c l e . B.1.4: Heat i s something that pushes the p a r t i c l e s of matter. One g i r l spoke of heat pushing p a r t i c l e s on. the pretest. She did not repeat this idea on the posttest, where she indicated that when matter i s heated the mechanical energy of the p a r t i c l e s increases, so that the p a r t i c l e s h i t one another 81 more and are farther apart. This posttest response r e f l e c t s the explanation presented in class and may or may not have been rote learned. B.1.5: Cold i s a d i s t i n c t thermal e n t i t y . A c a r e f u l reading of some of the students' responses revealed that at least three of them thought of cold as being something d i f f e r e n t from heat. Jane and Joe were among the three. For example, on the posttest, Jane said that metal feels colder than wood "because i t conducts cold better." SUMMARY: Several students spoke of heat p a r t i c l e s or molecules, although they did not use these terms consistently. The extent to which this idea was believed i s not c l e a r . The idea that heat moves between p a r t i c l e s of matter was expressed by more students on the posttest than on the pretest. The idea of heat pushing p a r t i c l e s was mentioned by one student, and only on the pretest. The notion o f "pushing" was expressed in other contexts, and w i l l be discussed again. The concept of heat energy may be plausible in i t s simplest form, but for many of the students, i t was not f r u i t f u l . Idea B .2 : When matter is heated/cooled many changes in the matter can be observed. As indicated above, there was often ambiguity in questions that were posed for the students. For example, on the f i r s t day of the unit, the teacher asked, "What happens to substances when p a r t i c l e s slow down?" Although the teacher was in the midst of a discussion about the rela t i o n s h i p between temperature and the speed at which the p a r t i c l e s were moving, Jane answered, "become 82 s o l i d ? " The teacher looked surprised and responded, "It's kind of a hard question," (considering i t had been discussed minutes before, i t r e a l l y was not that "hard"). Jane however, repeated her answer. The teacher then affirmed Jane's response, "Become s o l i d , " and added, "They r e a l l y get cold." When students were asked what happens when matter i s heated, they tended to focus on a change that could be seen macroscopically. The most commonly given response involved a change of phase or a change in p o s i t i o n . Usually, one or more of the following responses was given: B.2.1: The temperature goes up/down. This statement might seem to be the most obvious answer to the question "what happens when something is heated?" The students believed t h i s so firmly that many of them were unwilling to accept the data from the investigation of temperature change during phase changes. This idea w i l l be discussed in d e t a i l l a t e r when the d i s t i n c t i o n between heat and temperature i s examined (Topic D). B.2.2: Matter expands/contracts. A l l of the students had had experience with 1iquid-in-glass thermometers which u t i l i z e the property of thermal expansion. However, there was some confusion about what causes a l i q u i d to r i s e in a glass tube as i t is being heated. On the pretest/posttest students were asked why l i q u i d in a glass tube r i s e s when i t i s placed in b o i l i n g water, and whether the statement, "hot water r i s e s " i s a good explanation of that observation. Susan agreed on both tests that i t was a good explanation, and her partner, Carolyn, agreed on the posttest. 83 Neither g i r l explained why i t was a good explanation. Five other g i r l s and one boy agreed on the pretest and explained that when water b o i l s i t r i s e s — e i t h e r i t bubbles up, evaporates or is given off as steam. A l l of these phenomena were judged to be " r i s i n g . " On the posttest one of those fiv e g i r l s and a d i f f e r e n t boy agreed with the statement. Both students gave explanations that were derived from convection, suggesting that hot water r i s e s because i t i s less dense than cold water. Thus the explanations given on the pretest and on the posttest were quite d i f f e r e n t . The pretest explanations referred to r i s i n g due to b o i l i n g or evaporation. However, on the posttest r i s i n g was said to be due to a decrease in density. Ideas about convection appear to have led the students to an al t e r n a t i v e b e l i e f not expressed prior to i n s t r u c t i o n . One other g i r l gave a very interesting explanation on the posttest. She said i t was a good explanation "because i t ' s true but i t ' s just not s c i e n t i f i c but i t ' s good enough for the average person." The students had no d i f f i c u l t y with assigned questions asking about thermal expansion with respect to loosening the metal l i d of a jar or expansion/contraction of metal telegraph wires, bridges or railway tracks, suggesting they are comfortable with the idea that metals expand when they get hotter. However, some d i f f i c u l t i e s arose when students attempted to explain why a bimetallic s t r i p bent when heated. Gordon said that the p a r t i c l e s got more energy and spread apart and thus the s t r i p became heavier, bent and stretched. The teacher acknowledged that he was correct on the f i r s t part--the metal did expand. She did not deal with Gordon's idea that the 84 metal became heavier as i t expanded. The following period when the demonstration was being discussed, the teacher said that the rod bent because i t contained two di f f e r e n t metals which expanded d i f f e r e n t l y . Joe suggested that the rate of expansion for the two-metals was d i f f e r e n t , but that eventually both would expand by equal amounts. Alan proposed that the two metals "expand at di f f e r e n t heats," and another boy in the class said they would melt. Jane suggested that one metal expanded more than the other, and her response was accepted by the teacher. Alan then asked why his idea was not correct, and the teacher responded with a rather lengthy explanation. Alan looked very attentive throughout the explanation, and did not question the teacher further, but he later told the investigator that he had not understood the explanation. B.2.3: Matter r i s e s . On the posttest some students confused thermal expansion and convection phenomena when considering why matter " r i s e s " when heated. As mentioned above, one question on the test asked why the water l e v e l in a glass tube rose when the water was heated. The responses given on the pretest were diverse, and included: 1. the p a r t i c l e s move faster and/or spread out and/or the spaces expand (3 students). 2. the p a r t i c l e s expand (3). 3. the water wants to get out (1). 4. bubbles are pushing up the l i q u i d ; i t bubbles up (2). 5. because i t is evaporating (2). 6. hot water r i s e s (3). 85 7. a i r displaces the water and forces i t up the tube (1). 8. pressure created by the heat forces i t up the tube (1). Only the f i r s t of these i s consistent with the school science view. On the posttest fewer alternative b e l i e f s were expressed: 1. the p a r t i c l e s expand (3). 2. convection (2). 3. the spaces expand and mechanical energy pushes the l i q u i d up (1). 4. the b o i l i n g water is pushing the l i q u i d (1). 5. the water molecules are more active and push themselves up (1). Several students mentioned the idea of a push or force being involved. The students were not asked to elaborate on any of the responses in which they used these terms, but i t would have been interesting to hear more about these ideas. Later when convection i s discussed we s h a l l encounter such'forces again. Two other pretest/posttest questions dealt with warm or hot a i r . One asked where in a classroom would you expect to find the warmest a i r . Nearly a l l students replied that the warmest a i r would be near the c e i l i n g because warm/hot a i r r i s e s . The other question presented an empty syrup can with a balloon over the opening. Students were f i r s t asked what would happen to the balloon i f the can were upright and heated by a bunsen burner set below the can. Secondly, they were asked what would happen i f the can were again heated from below, but inverted so that the balloon was attached to the lower surface. Students predicted that the balloon on the upright can would be blown up by the heated a i r . Two types of reasons were given. Most 86 students said that warm a i r r i s e s . Others said that the a i r expanded into the balloon, with a few students predicting that both would occur. D i f f i c u l t i e s arose when students were explaining what would happen when the can was inverted. Most students, having said that warm a i r r i s e s , said that warm a i r would ri s e to the top and hence the balloon would not i n f l a t e . Most of those who did predict that the balloon would i n f l a t e said i t would do so because the a i r was expanding in a l l dir e c t i o n s . Only one student, a boy, gave a hint of the idea of convection on the pretest, when he said the balloon would expand because as the hot a i r ris e s i t pushes the cold a i r down. During the pretest interviews, Jane and Brian had both conceded that the balloon on the inverted can might expand a b i t i f the can were heated long enough and there was not enough room at the top for a l l of the hot a i r . •» However, neither suggested t h i s p o s s i b i l i t y on the posttest. Carolyn, Alan, Gordon and two other students (both male) did refer to convection in the i r posttest explanations. B.2.4: Matter softens, melts, l i q u i f i e s , b o i l s , evaporates/hardens, freezes, s o l i d i f i e s , condenses. Understanding the process of phase change was very d i f f i c u l t for some of the students, and a variety of alte r n a t i v e b e l i e f s were expressed. This topic w i l l be examined in d e t a i l in connection with the heat/temperature d i s t i n c t i o n (Topic D). B.2.5: Matter gets heavier/lighter. These common alternative b e l i e f s about the behaviour of matter when i t is heated/cooled appear to ar i s e from confusion about the process of thermal expansion. Some students seemed to 87 believe than i f an object gets bigger, i t w i l l also become heavier. Others appeared to think that because the object becomes less dense when i t expands, i t w i l l also become l i g h t e r . The d i f f i c u l t y appears to derive from confusion about the concept of density and/or the law of conservation of matter. Both topics had been studied prior to thi s unit, and thermal expansion was being presented with the assumption that students did have s c i e n t i f i c a l l y appropriate understandings of both density and the conservation of matter. Responses made by some of the students suggest that they believed i t was changes in the p a r t i c l e s themselves, rather than in their energy levels and the r e l a t i v e distance between the p a r t i c l e s , that was responsible for thermal expansion and contraction. Examples of such b e l i e f s are presented in the next idea. SUMMARY: Students understood that many di f f e r e n t kinds of changes occur when matter i s heated. The temperature increases, the volume usually increases and a change of phase may occur. In addition, when f l u i d s are heated, they " r i s e . " The most frequent responses involved a change of phase or rising—changes the students could see. The s c i e n t i f i c p r i n c i p l e s behind these phenomena were not always c l e a r . The ideas about temperature change and thermal expansion were i n t e l l i g i b l e and they were plausible to some. Once again, they were not f r u i t f u l . Idea B.3: We make inferences about the behaviour of p a r t i c l e s when matter i s heated/cooled. D i f f i c u l t i e s with two of the fundamental d i s t i n c t i o n s appear to account for the alternative b e l i e f s about the 88 behaviour of the p a r t i c l e s . F i r s t , both the textbook and the teacher stressed the idea that i t i s the spaces, and not the p a r t i c l e s , that "expand" when matter is heated. This is presumably intended to counteract the be l i e f held by many students, that the p a r t i c l e s themselves expand and contract. Secondly, some students confused the macroscopic behaviour of matter with the behaviour of the p a r t i c l e s . This d i f f i c u l t y i s not addressed in the textbook, nor was i t discussed in cl a s s . B.3.1: When matter i s heated: the mechanical energy of the p a r t i c l e s increases; the p a r t i c l e s move faster; the p a r t i c l e s h i t one another more frequently. The textbook presents the idea that the heat energy of an object i s the t o t a l mechanical energy of the p a r t i c l e s in the object, and hence heating an object w i l l result in an increase in that mechanical energy. None of the students referred to an increase in mechanical energy on the pretest. On the posttest Jane and three others did so, although one g i r l said, "the spaces between the p a r t i c l e s expand and gain more mechanical energy." On the pretest, she and Jane had both said the p a r t i c l e s moved faster. Most of the students talked about p a r t i c l e s moving faster when heated on the posttest. Only three students (Alan and two others) made no mention of either the p a r t i c l e s gaining mechanical energy or moving faster at that time. Altogether, ten students spoke of p a r t i c l e s moving faster on the pretest and 17 on the posttest. A few students noted that the p a r t i c l e s h i t one another more frequently when matter i s heated. Cathy and another g i r l said, this on both tests, whereas Alan, Gordon and two other g i r l s expressed t h i s idea 89 only on the posttest. B.3.2: When matter i s heated: the p a r t i c l e s are farther apart; the spaces expand or get bigger. As mentioned above, the textbook stresses the idea that when matter i s heated the spaces between the p a r t i c l e s get bigger. In the textbook, the review questions at the end of the chapter refer to spaces: What happens to the spaces between the p a r t i c l e s of a i r when a i r i s heated? How does th i s change the density of the air? Explain your answer. (Schmid and Murphy, 1979, p. 125) The suggested answers provided in the teachers' guide indicate that the students should respond that the spaces between the pa r t i c l e s become larger. It would appear that the authors f e l t that they could better emphasize the lack of expansion of pa r t i c l e s by indicating that i t i s the spaces that become larger, rather that saying that p a r t i c l e s spread apart. Susan's response to the question about what happens to the size of the pa r t i c l e s was, "The p a r t i c l e s between the a i r expand..." A l l other students (including those who were to say later that p a r t i c l e s expand when matter i s heated) responded that the spaces would become larger. Thus i t appears that emphasing the expansion of spaces did not necessarily d i s c r e d i t expanding p a r t i c l e s . B.3.3: When matter is heated: p a r t i c l e s expand, increase in mass, decrease in mass, or melt. Students who expressed one or more of these b e l i e f s had not disinguished between the observable behaviour of matter and the unobservable behaviour of p a r t i c l e s , a d i s t i n c t i o n previously i d e n t i f i e d as a key source of d i f f i c u l t y for several students. 90 As mentioned above, the idea that thermal expansion occurs because the p a r t i c l e s (atoms or molecules) have expanded i s very common. Nine of the 23 students in the class expressed t h i s idea on the pretest and/or in c l a s s . Because the question, "Do p a r t i c l e s expand when matter is heated?" was not asked d i r e c t l y , we cannot be certain about the b e l i e f s of those who did not refer to p a r t i c l e s when explaining thermal expansion. However, there were only three students who made no mention of either p a r t i c l e s , atoms or molecules on either the pretest and/or the pretest interview. On the posttest, fiv e students s t i l l e x p l i c i t l y stated the b e l i e f that the p a r t i c l e s expand when matter i s heated. . Two students spoke of p a r t i c l e s becoming heavier when they expanded. On the pretest Carolyn said that, "water p a r t i c l e s expand when they're heated so they have a greater mass." Although Carolyn's response may have been correct according to s c i e n t i s t s ' science, i t was incorrect from the school science perspective. When the bimetallic s t r i p was being heated Gordon predicted that i t was bending downwards because the p a r t i c l e s were getting more energy and spreading apart, and i t became heavier. The teacher responded that Gordon was right on the f i r s t part, but she did not deal with his suggestion that the s t r i p got heavier. The next day just before the end of the period, one of the g i r l s spoke to the teacher p r i v a t e l y and said that she thought that the mass must change when something gets bigger. She pointed out that i f we get bigger our mass changes. As the b e l l was ringing the teacher t o l d her that the mass did not change. Two days l a t e r , while discussing properties which 91 change when matter is heated, another g i r l gave mass as an example. The teacher responded by asking i f any p a r t i c l e s were to be thrown away, and the students said no. As the discussion continued some students said when water evaporates some p a r t i c l e s are given o f f . The teacher then agreed that there could be a change in mass in this s i t u a t i o n . She did not point out that the water has gone somewhere else, rather than i t s mass actually changing. Later, when Investigation 1.42 (The heat energy and temperature of diff e r e n t objects) was being discussed, the teacher herself referred to mass "changing" rather than speaking of d i f f e r e n t masses (or of changing to an object of di f f e r e n t mass), undoubtedly further confusing the issue. This investigation w i l l be discussed in more d e t a i l in the next chapter. Other students spoke of p a r t i c l e s becoming l i g h t e r when matter was heated. This idea was provided by Cathy as an explanation of why matter r i s e s when i t is heated, and w i l l be further discussed in the section dealing with convection. None of the questions on the posttest or unit test addressed the matter of mass changing, and none of the students said anything about i t on either test. A f i n a l alternative b e l i e f to be examined in thi s section is the idea that p a r t i c l e s melt when matter i s heated. On the pretest Cathy used the terms "melt" and "dissolve" interchangeably. She did not use the l a t t e r term on the post-te s t . However, when explaining why the ice cube melts she responded that the p a r t i c l e s get warmer and melt. Again, Cathy 92 did not dis t i n g u i s h between the behaviour of matter and the behaviour of the individual p a r t i c l e s . SUMMARY: Many students appear to have assumed that observable changes in matter also occur in p a r t i c l e s . That i s , i f matter expands, the p a r t i c l e s are expanding. An attempt to correct t h i s p a r t i c u l a r alternative b e l i e f by concentrating on the spaces was not e f f e c t i v e for some students. They apparently saw no c o n f l i c t in the two phenomena. None of the other s p e c i f i c alternative b e l i e f s discussed in t h i s idea (e.g., p a r t i c l e s melt) were discussed in cla s s . Topic C: Temperature and How It Is Measured Most thermometers depend on the property of thermal expansion, discussed above. The students investigated temperature by finding the freezing and b o i l i n g points of water using a mercury thermometer (Inv. 1.37). When discussing the investigation the teacher asked for d e f i n i t i o n s of temperature. One student responded, "how hot i t i s . " Another said, "the heat that's contained within the object," a response repeated by the teacher and then ignored. Brian then replied, "how hot something or how cold something i s , " whereupon the teacher said, "the hotness or coldness of an object." She then t o l d the class to write that down in their notebooks. Idea C.1: De f i n i t i o n s of Temperature C.1.1: Temperature i s a measure of the average mechanical energy of the p a r t i c l e s . This d e f i n i t i o n , provided in the textbook, was rarely 93 expressed by either the students or the teacher. When students were asked to define temperature on the unit test, only Jane and one other boy gave th i s d e f i n i t i o n (Jane also gave the alternative d e f i n i t i o n ) . Another g i r l r eplied, "an approximation of how much mechanical energy the p a r t i c l e s have each a l l together," evidently confusing the textbook d e f i n i t i o n s of heat and temperature. This d e f i n i t i o n was not i n t e l l i g i b l e to the students. C.1.2: Temperature is the hotness or coldness of an object or of matter. This d e f i n i t i o n i s also provided in the textbook (Schmid and Murphy, 1979, p. 110) and i t was emphasized by the teacher in c l a s s . Ten students used t h i s d e f i n i t i o n on the unit t e s t . Two of them, Brian and Joe, said temperature was a measure of how hot or cold something i s . Some unacceptable responses which may have been derived from t h i s d e f i n i t i o n include those of two students who simply said i t was a measure and one g i r l who replied, "how hot the p a r t i c l e s are," another instance of confusing the d i s t i n c t i o n between the properties of matter and of p a r t i c l e s . C.1.3: Temperature i s a measure of the heat of an object or of matter. A surprising number of students defined temperature as a measure of heat or heat energy on the unit t e s t . Three students said i t was a measure of heat or heat energy, while Gordon and two other students said temperature was the heat being given out, or in the words of one boy, "the heat you can f e e l on the surface." One g i r l gave a d e f i n i t i o n that would more 94 appropriately define heat, the mechanical energy of the p a r t i c l e s a l l together. More detailed discussions of the d i s t i n c t i o n between heat and temperature follow under Topic D and in Chapter V. SUMMARY: Several students were s t i l l unable to provide an acceptable d e f i n i t i o n of temperature on the unit test, although both the textbook and the teacher stressed d e f i n i t i o n s . Many students s t i l l seemed to believe that temperature i s r e a l l y a measure of heat. Memorizing the complex d e f i n i t i o n s provided by the textbook or by the teacher did not necessarily displace that b e l i e f . In such cases, the school science d e f i n i t i o n of temperature was neither plausible nor f r u i t f u l . Idea C.2: The c h a r a c t e r i s t i c property of thermal expansion allows us to use the volume of a fixed amount of matter to indicate the temperature of that matter. Although th i s idea provided the rationale for the thermal expansion investigations (1.37 and 1.38) i t was not made e x p l i c i t to the students. The chapter review questions included the following: What properties of matter are affected by temperature? How are these properties used to measure temperature? (Schmid and Murphy, 1979, p. 125) Students appeared to be unaware of the meaning of the term, "property," as only one student answered t h i s question appropriately. Several students responded, " s o l i d , l i q u i d , gas," and others said volume or mass. Noting th i s d i f f i c u l t y , the teacher discussed the meaning of the term in c l a s s , but the second part of the question was overlooked in the discussion. 95 The topic was not raised again, nor was i t addressed on either the unit test or the posttest. Another textbook question, " L i s t f i v e changes in matter that are caused by changes in temperature" (Schmid and Murphy, 1979, p. 123) was not assigned. If students had had to answer t h i s question before coming to the review question c i t e d above, they may have been more successful on the l a t t e r . On the unit test the students were asked to explain how to c a l i b r a t e a thermometer. Those who understood Investigation 1.37 and this idea should have had no d i f f i c u l t y with the explanation. In fact, only 12 students answered the question c o r r e c t l y . SUMMARY: Although the students understood that substances expand when they are heated, most of them were unable to apply that knowledge to explain how a thermometer is c a l i b r a t e d . Again, the phenomenon of thermal expansion was plausible, but i t was not f r u i t f u l . Topic D: The Difference Between Temperature and Heat Energy Many students were s t i l l not clear about the d i s t i n c t i o n between heat and temperature on the posttest. The posttest included a set of questions concerning a large and a small ice cube placed in a beaker of water. Students were t o l d the small cube would melt f i r s t and they were then asked i f both cubes were the same temperature, why they thought the small ice cube would melt f i r s t , i f they thought that both cubes needed the same amount of heat to melt them and why. Students who c l e a r l y understood the d i s t i n c t i o n between heat and temperature should not have had d i f f i c u l t y with these questions. On the other 96 hand, students who assumed that temperature i s a measure of heat could be expected to say that both cubes needed the same amount of heat to melt. On the pretest 16 students, including many of the. more successful students (among them Jane and a l l other target students except Alan), did say the cubes needed the same amount of heat. Some students also said that the bigger cube just needed more time. On the posttest Jane, Carolyn and four other students s t i l l agreed with that view. Jane's incorrect responses on the posttest suggest that this idea was not c l e a r l y addressed during instruction ( i t i s very unlikel y that Jane would give an answer which had been i d e n t i f i e d as in c o r r e c t ) . On the pretest Jane said, "yes, the larger one w i l l just take longer." During the interview she reversed her answer and. said they would not need the same amount of heat. However, on the posttest Jane went back to her o r i g i n a l position and said, "yes, but the larger one w i l l take longer to melt\" Idea D.1: The amount of heat energy contained in matter depends on: the kind of material; the amount of matter; and the temperature of the matter. The idea that the temperature and the mass of matter influence the amount of heat energy in matter caused no d i f f i c u l t i e s . On the unit test 13 students gave both of these factors, and only one student missed both. Two g i r l s said mechanical energy, rather than temperature. However, the "type of material" caused problems. The textbook refers to the type of material as being one of the factors influencing heat energy. Density i s never mentioned in the text. The students however, 97 tended to assume that the relevant property was the density of the material, and then used t h i s term in their conclusions and when answering questions. This alternative b e l i e f was common in the p i l o t study class as well. During class discussions the students usually referred to density, rather than type of material. When they did so, the teacher t o l d them i t was better to refer to the type of material rather than the density. However, when grading assignments and tests, she did not penalize students for using the term. On the unit test students were asked to " l i s t three factors which aff e c t the heat energy of an object." Most students said type of material as one of their answers. Two boys said both density and type of material. However, Gordon gave neither and a l l of the other boys but one said density. Only one of the g i r l s , a very low achiever, gave density as an answer. It i s i n t e r e s t i n g that most of the boys persisted in using the term, whereas most of the g i r l s did not. It may be that the g i r l s , being more compliant, were more w i l l i n g to do as the teacher said ( i . e . , not use the term "density"), even i f the d i s t i n c t i o n made no sense to them. The students also tended to assume that a greater density meant more heat energy for equivalent temperature changes. Joe once made a statement to t h i s effect in c l a s s , and his error was not picked up by the teacher. SUMMARY: The students had no d i f f i c u l t i e s understanding that temperature and mass are related to heat energy. The idea that a property of matter other than density was also a factor was apparently too abstract and nebulous for most of them. At no time was i t s p e c i f i c a l l y stated that i f mass and type of \ 98 material (or density), as well as temperature affect the amount of heat energy in the material, then temperature and heat cannot be the same, and temperature cannot be a measure of heat alone. The students were apparently expected to recognize t h i s themselves. In fact, most of them did not. Idea D.2: When matter is heated the rate at which the temperature increases i s not constant when a phase change occurs. As we saw in the discussion of Topic B, the students were convinced that the temperature of matter should increase as long as the matter is being heated. The second investigation in chapter 8 (Inv. 1.45) examines heat and temperature during phase changes. The introduction states, "In th i s Investigation you w i l l see what difference a material's phase makes to i t s heat energy" (Schmid and Murphy, 1979, p. 135) The questions to be answered by the investigation are: 1. Which has more heat energy--ice at 0°C or the same mass of water at 0°C? 2. Which has more heat energy—ice at 100°C or the same mass of water vapor at 100°C? 3. Which takes the most heat energy—melting ice, r a i s i n g the temperature of the l i q u i d water from 0°C to 100°C, or b o i l i n g away a l l the water? (Schmid and Murphy, 1979, p. 1 35) The investigation involved measuring the temperature of ice and water in a beaker, as i t was being heated. Readings were taken every two minutes u n t i l the water boiled. Students were expected to note that although the water was heated constantly, that during a phase change the temperature remained r e l a t i v e l y constant. However, th i s was not what they expected, and as we 99 s h a l l see, some of them did not believe the results were correct. None of the questions on the pre/posttest addressed th i s issue, but i t was a topic which Alan and one other boy had discussed e a r l i e r . Brian also expressed concern about th i s matter, a concern which was' not s a t i s f a c t o r i l y resolved. This investigation, i t s results and the confusion that arose during the discussion of the investigation, w i l l be discussed in more d e t a i l in Chapter V. SUMMARY: The d i s t i n c t i o n between heat and temperature was never c l e a r l y resolved for many of the students. Although students were able to r e c i t e d e f i n i t i o n s and d i s t i n c t i o n s , the posttest revealed that many did so with no understanding. The d i s t i n c t i o n was i n t e l l i g i b l e to some, but not a l l . Topic E: Heat Transfer Although the students appeared to be r e l a t i v e l y familiar with the concept of conduction, they knew l i t t l e about convection or radiation. Some used the term "conduction" on the pretest, while others referred to heat being either "absorbed" or "attracted" when explaining conduction phenomena. The teacher accepted both of these terms as being equivalent. Students frequently mentioned density as a factor influencing heat transfer, although t h i s idea i s not mentioned in the textbook, nor did the teacher introduce the idea. However, as was indicated e a r l i e r , neither did she t e l l them i t was incorrect. Heat transfer was dealt with very h a s t i l y . The students were given hand-outs b r i e f l y describing conduction and 100 convection, and they were not asked to read the text on these topics, although questions from the text were assigned. Conduction, convection and radiation were a l l discussed in class , and simple demonstrations i l l u s t r a t i n g the f i r s t two phenomena were performed by the teacher. As s h a l l be seen, these demonstrations did not always produce the desired r e s u l t s . Idea E.1: Conduction The students were aware that hot objects become cooler i f they are placed in a cooler environment and vice versa. E.1.1: Conduction is the "transfer of heat energy that takes place when faster p a r t i c l e s make nearby p a r t i c l e s speed up by h i t t i n g them." (Schmid and Murphy, 1979, p. 42) .On the unit test students were asked to explain conduction using the p a r t i c l e model. Thirteen students got f u l l marks on this question. Only Carolyn, Alan and four others got less than half marks (Alan described convection, rather than conduction), indicating that most students were able to s a t i s f a c t o r i l y explain the behaviour of p a r t i c l e s when heat i s conducted. E.1.2: Conduction occurs when heat i s transferred from hotter matter to cooler matter u n t i l both are at the same temperature. Everyday experience t e l l s us that i f something i s removed from a hot oven or a cold r e f r i g e r a t o r i t s temperature changes to something approximating room temperature. On both the pretest and posttest a l l students knew that i f a hot n a i l were dropped into a beaker of cold water, the n a i l would get cooler and the water would get warmer. Most students did not however, predict that they would reach the same temperature (ten 101 predicted they would become equal in 30 minutes or less on the pretest; the same ten plus two more made the same prediction on the p osttest). Another set of questions on the pre/posttest dealt with a shovel l e f t outdoors on a frosty night. Students were asked why the metal f e l t colder than the wood and what temperature they would expect the wood and the a i r to be i f the metal were -3°C. On the posttest, six students (including Alan and Cathy) predicted the a i r temperature would be -3°C. Only Alan and Susan predicted the temperature of the wood would be -3°C. Although many students recognized that the two substances conduct heat (cold) d i f f e r e n t l y , only Alan said that the wood and metal "absorb [ i . e . , conduct] heat from your hand." Three students, Jane and Joe included, referred to cold, rather than heat. A similar question, why perspiration cools the body, was assigned from the textbook. That question was discussed in class and almost a l l of the students had i t correct when they handed in the assigment. In addition, the teacher had discussed the phenomenon in class, asking as an example, why the metal gas faucets on the laboratory tables f e l t colder to the touch than did the table top. Alan responded that the tap f e l t cooler because " i t ' s taking our heat." In spite of t h i s , none of the students, except Alan, recognized that a l l parts of the shovel would be the same temperature as the a i r temperature. Students who had developed the desired understanding of conduction should have been able to answer the shovel questions c o r r e c t l y . Only Alan did so, and his answers did not d i f f e r on the pretest and the posttest. 102 E.1.3: The rate at which conduction occurs depends on the type of material. . Many students did not recognize that a metal rod would conduct .heat more rapidly than a glass rod. On the pretest six students predicted the metal would conduct faster, and 12 that the glass would. On the posttest ten predicted metal and nine glass. Jane, Gordon and two other boys predicted c o r r e c t l y on both t e s t s . Alan, two other boys and three g i r l s were correct on the posttest only. Two of those who predicted c o r r e c t l y on the pretest did not do so on the posttest, suggesting they may have guessed on the pretest. Again density was assumed to be the relevant property of the material. On both tests, Joe and Brian said the glass would conduct faster because i t is less dense. On the posttest, Cathy and two other g i r l s agreed with Joe, while Alan and two other boys said glass conducted more slowly because i t was less dense. The idea that heat i s conducted through the spaces has been discussed e a r l i e r (Idea B.1.3.). Those who predicted that a less dense object would conduct more slowly may have had one of two a l t e r n a t i v e b e l i e f s . The f i r s t p o s s i b i l i t y , mentioned e a r l i e r , i s the idea that heat moves between p a r t i c l e s of matter and hence travels faster when i t has more room. This idea was expressed by Carolyn on the pretest and by Susan and three others g i r l s on the posttest. One g i r l explained, "The heat has to move in between the p a r t i c l e s spaces." Another g i r l spoke of heat p a r t i c l e s moving through matter. The second al t e r n a t i v e b e l i e f was expressed by Brian during the interview. He said that when p a r t i c l e s of matter were farther apart they had more room to move around and 1 03 thus were able to speed up more quickly. Brian's alternative b e l i e f i s much closer to the school science view as i t recognizes the importance of the increased rate of motion of the p a r t i c l e s . On the pretest, Susan and three other g i r l s said glass would not conduct at a l l . One other g i r l said glass and metal would conduct at the same rate on both the pretest and the posttest.. SUMMARY: The students understood conduction in a q u a l i t a t i v e sense prior to the unit. At the end of the unit, when required to explain conduction using the p a r t i c l e model, half the class was able to do so. However, the posttest responses to items concerning conduction revealed that many students s t i l l held alternative b e l i e f s . Idea E.2: Convection i s the "transfer of heat energy by a hotter f l u i d moving to a colder place" (Schmid and Murphy, 1979, p. 150). Convection was not at a l l well understood. As mentioned e a r l i e r , from the beginning students believed that heat or hot a i r r i s e s . On the pretest everyone but Susan said that the a i r in a closed room would be warmest near the c e i l i n g . Susan said i t would be warmer near the middle "because of the heater." (There was no heater mentioned in the question.) The confusion began when the students were asked to go beyond that idea. Some of the students seemed to confuse thermal expansion and convection. This i s not too surprising as convection r e a l l y does occur as a result of expansion and the consequent reduction in the density of the matter. Some also confused the properties 104 of matter with those of p a r t i c l e s . For example, on the posttest both Brian and Cathy said warmer p a r t i c l e s are li g h t e r and r i s e . A more d i f f i c u l t question posed the situation in which an empty metal container had a balloon placed over the opening. Students were asked what happened in the container and to the balloon when the can was heated, f i r s t from the bottom, and secondly when i t was inverted (so that the balloon would be at the bottom). On the pretest students either said the a i r would r i s e or i t would expand or both. They therefore predicted that the balloon would fe e l warm when the can was upright and the balloon was on the top, but not when i t was inverted so that the balloon was on the bottom. Most students repeated t h i s idea on the posttest. As they did on the pretest, Jane and Joe said that when the a i r was heated i t would expand and the hot a i r would r i s e to- the top, and therefore the balloon would not expand or fe e l warm. To quote Carolyn, when the balloon is on top i t w i l l blow up because, "convection would force the a i r to r i s e . " When the can is inverted, "the balloon would not f i l l up. Hot a i r never goes downward." Thus Carolyn viewed convection as hot f l u i d r i s i n g , but not c i r c u l a t i n g . On the posttest only four boys (and no g i r l s ) i d e n t i f i e d t h i s question as an example of convection, and co r r e c t l y predicted that the inverted balloon would not only expand, but also f e e l warm. That i s , very few students appeared to understand convection as a cy c l e . On the unit test students were asked to draw arrows showing "the d i r e c t i o n of the convection current" over a land-sea interface. Seven students drew the correct cycle, among them 105 Jane, Brian and Alan. Most others either drew the cycle in reverse (eight students) or showed the a i r r i s i n g , but not cyclin g (fi v e students). One student who did the l a t t e r explained, "the cool a i r w i l l force the warm a i r upwards convection only works upwards." The above response also provides an example of another somewhat misleading belief - - t h e idea that either warm or cold a i r pushes or forces the other to move. On the handouts given to the students, diagrams show a simple a i r convection demonstration and a hot water heating system. The captions say that the cooler f l u i d (either the a i r or water) "forces the. warm a i r [or water] to r i s e . " When convection was discussed in clas s , the teacher asked i f someone could "explain how convection would work." Jane gave the following response: If you have some water and you heat up part of that water, the water that you heat up, the p a r t i c l e s w i l l move farther apart,'the water w i l l have more heat energy, so the heated water gets l i g h t e r than the cold water, so the cold water is heavier and i t pushes.the hot water and so that's how i t ' s moving around." Jane does not appear to have recognized that the warmer water tends to r i s e at the same time as the cooler water i s sinking, and thus she misses the idea of the c i r c u l a t i o n of the water. Even in the textbook this confusing view i s presented: ...the colder f l u i d sank because i t -was denser than the warmer f l u i d . Therefore, the warmer f l u i d was pushed up. When the warmer f l u i d rose, i t car r i e d i t s heat energy with i t . (Schmid and Murphy, 1979, p. 150) SUMMARY: A l l in a l l , very few students seemed to view convection as a process which involves a f l u i d c i r c u l a t i n g because one part of i t i s warmer and hence less dense than the other part. 1 06 Idea E.3: Infra-red rays, l i k e l i g h t rays, are a form of electromagnetic radiation that travel through space. They can be ref l e c t e d and refracted, just as l i g h t rays can. When an object absorbs infra-red ,rays, i t s p a r t i c l e s gain mechanical energy. When an object radiates (infra-red rays) i t s p a r t i c l e s lose mechanical energy. Therefore, infra-red rays seem to carry heat energy from one object to another. (Schmid and Murphy, 1979, p. 163) Other than the unit test, information about the students' ideas about radiation i s sparse. On the f i n a l day of cl a s s , the teacher reviewed conduction and convection, and introduced the topic of radiation. The main ideas introduced were that hotter objects radiate more heat than cooler objects, the effect of colour on r e f l e c t i o n and absorption of heat, and the greenhouse e f f e c t . At the end of the period she dist r i b u t e d copies of the review summary from the heat transfer chapter (Chapter 9), saying, "These sheets are a review for your test. They review the material." The review questions were neither handed in nor discussed in class, and no other reading or questions were assigned. Three questions on the unit test dealt with radiation. One question asked how the sun's energy reaches us. Students were also asked to describe the clothing they would wear i f the temperature were -60°C and how i t would keep them warm. The th i r d question asked which would radiate more—your body at 37°C, or your surroundings on a hot day of 30°C, and what kind of clothing would help you stay cool. A l l but fi v e students (four boys and one g i r l ) recognized that the sun's energy 107 reaches the earth by radiation. Only Joe, two other boys and one g i r l got the f u l l three marks on the question about clothing for -60,°. They were required to refer to: warm clothing (good i n s u l a t i o n ) , keeping in body heat, and dark colours. The remaining students got one and one-half or two marks. Thus, o v e r a l l the students answered t h i s question f a i r l y well, as they did the question about dressing for a hot day. However, ten students did not recognize that the body, being warmer, radiates more heat per unit area than i t s surroundings. Joe, Brian, Cathy and Susan were among the ten. Joe explained that the body radiates less heat "because your body retains i t s heat and your surroundings don't." This question required the students to apply their knowledge of radiation to a s l i g h t l y d i f f e r e n t s i t u a t i o n than had been discussed in c l a s s . Many of them were unable to do so. SUMMARY: Most of the students were able 1 to id e n t i f y factors influencing absorption and r e f l e c t i o n of radiant energy, and factors that make clothing either a good or a poor insulator. The idea that a l l matter radiates heat energy was not well understood. 4.5. Summary This chapter has examined many di f f e r e n t ideas about heat and temperature. , The s c i e n t i f i c perspective was presented and contrasted with the textbook and curriculum perspective. These perspectives have been referred to as " s c i e n t i s t s ' science" by Gi l b e r t et a l . (1982) and "school science," by Driver and Erickson (1983). 1 08 The major portion of the chapter has been devoted to a detailed examination of "children's science." That i s , of the students' ideas prior to instruction and to a discussion of how those ideas changed in the course of a unit of study. We have seen that many of the alternative b e l i e f s were related to one or more of three p a r t i c u l a r l y d i f f i c u l t d i s t i n c t i o n s i d e n t i f i e d in the section on children's science. These were: 1. the idea that matter consists not only of p a r t i c l e s , but includes the spaces between the p a r t i c l e s as well; 2. the idea that the behaviour of p a r t i c l e s i s not the same as the observable behaviour of matter; and 3. the d i s t i n c t i o n between heat and temperature. The examination of children's science i d e n t i f i e d several alternative b e l i e f s that were s t i l l expressed by some students on the unit test and/or the posttest. Moreover, some students had changed their ideas to a less s c i e n t i f i c view than they had held before, riot an unusual occurence, according to Osborne and Wittrock (1983). Students were found to have pa r t i c u l a r problems with the school science explanations of the following topics: 1. The thermal expansion of matter, at the p a r t i c l e l e v e l . 2. The nature and extent of the spaces between the p a r t i c l e s of matter. 3. The nature of heat and the difference between heat and temperature. 4. The type of material as a factor related to the heat energy ( i . e . , internal energy) of matter. 5. When matter i s heated, the rate of temperature change i s not 109 constant when a change of phase occurs. 6. The difference between heat and cold. 7. The eff e c t of heating on d i f f e r e n t kinds of matter. 8. How conduction occurs, at the p a r t i c l e l e v e l . 9. The eff e c t of the type of material on the rate at which heat is transferred by conduction. 10. How heat i s transferred by radiation. The next chapter w i l l take a closer look at learning and w i l l examine in more d e t a i l the interaction between school science and children's science. 1 10 CHAPTER V CHILDREN'S SCIENCE: LEARNING 5.0. Introduction To some, a school i s a place where teachers teach and children learn what i s taught. This view of teaching and learning seems to assume that i f teachers present information in a l o g i c a l way, at an appropriate l e v e l of complexity (or simp l i c i t y ) and i f students complete the required a c t i v i t i e s and assignments, then the' students w i l l necessarily achieve the intended learning outcomes and understanding. For students who are both i n t e l l e c t u a l l y competent and achievement-oriented t h i s view may be r e a l i s t i c . Three of the target students, Jane, Cathy and Susan, each in her own way, worked d i l i g e n t l y to learn what was taught. There is no doubt that a l l of the g i r l s did learn something about heat and temperature during t h i s unit. However, the products of their e f f o r t s were very d i f f e r e n t - - i n part, the result of d i f f e r e n t sets of prior b e l i e f s interacting with d i f f e r e n t cognitive a b i l i t i e s . For Jane, most of the learning appeared to be meaningful. For Cathy and Susan, much of i t was meaningless memorization. However, Cathy was much more successful than Susan at u t i l i z i n g what was memorized in a test s i t u a t i o n . If we examine unit test marks for each g i r l , we see that Jane and Cathy did much better than Susan (Table 5.1). However, does th i s necessarily mean that Jane and Cathy learned 111 more than Susan? On the pretest Jane and Cathy received approximately equal scores. However, Cathy's posttest score was somewhat lower than her pretest score, whereas the other two g i r l s showed substantial gains from pretest to posttest. Jane's scores increased for a l l l e v e l s , whereas Susan's gains were only on Level 1 questions (see Table 2.1 for descriptions of l e v e l s ) . Based on pretest-posttest gains, Jane and Susan appear to have learned more than Cathy. Observations such as these raise many questions as to how we should define learning. Table 5.1 Test Scores for Three Selected Target Students Jane Cathy Susan Max. Pre Post i Gain Pre Post Gain Pre Post Gain Score Level 1 18 21 3 18 17 (-1) 9 16 7 21 Level 2 7 12 5 8 3 (-5) 2 1 (-1 ) 1 5 Level 3 3 6 3 2 4 2 1 0 (-1 ) 1 1 Total Test 28 39 1 1 28 24 (-4) 1 2 17 5 47 Unit Test 94% 80% 59% 100% In the previous chapter several perspectives of heat and temperature were discussed. Many of the b e l i e f s held by the students were presented and examined. Some of those b e l i e f s are compatible with current s c i e n t i s t s ' science and/or with school science. However, without exception, on the posttest every student s t i l l held at least some of the alternate b e l i e f s that 1 12 had previously been expressed on the pretest. The great majority of these b e l i e f s had been addressed in the textbook and/or during i n s t r u c t i o n . Why did the students f a i l to revise some of their prior alternate b e l i e f s , even when these ideas were repeatedly refuted in the textbook and by the teacher? The overriding aim of t h i s study has been to try to shed some l i g h t on t h i s key question. In t h i s chapter, we w i l l examine what the students "learned" during the unit. Before t h i s can be done, we must c a r e f u l l y define what we mean by "learning." Although many would, define learning as a change in behaviour, the most commonly used measures of learning in our secondary schools assess the extent of knowledge and/or s k i l l s demonstrated by the student at various intervals throughout the school year. In t h i s study we w i l l consider three operational d e f i n i t i o n s of learning: 1. learning as demonstrated by success in school science, 2. learning as demonstrated by success on the posttest, and 3. learning as demonstrated by gains from the pretest to the posttest. The extent to which individual students and the class as a whole have been successful according to each of these c r i t e r i a w i l l f i r s t be examined. Class data w i l l be examined to id e n t i f y student c h a r a c t e r i s t i c s which were related to the various c r i t e r i a for success. P a r t i c u l a r l y successful and p a r t i c u l a r l y unsuccessful students w i l l be i d e n t i f i e d to determine the extent to which those c h a r a c t e r i s t i c s of success t y p i f y individuals. The chapter w i l l conclude with an examination of those content 1 1 3 areas where learning was not successful for many students—the persistent alternative b e l i e f s . 5.1. Analysis of the Data A l l of the data c o l l e c t e d were u t i l i z e d to investigate what the children had learned about heat and temperature. Both q u a l i t a t i v e and quantitative analyses were conducted. 5.1.1. Qualitative Analysis The previous chapter has already described the q u a l i t a t i v e analysis of student b e l i e f s about heat and temperature. A further examination of a l l of the tr a n s c r i p t s , tests and assignments was conducted to consider possible explanations as to why some alternative b e l i e f s were so persistent. 5.1.2. Quantitative Analysis The investigator scored a l l responses on the pretest and posttest as either correct or incorrect, according to the c r i t e r i a provided by the test developers (Shayer, Note 3). As described e a r l i e r , each item had been categorized according to topic(s) and d i f f i c u l t y l e v e l . The LERTAP (Nelson, 1974) program was used to score and analyse the test responses. LERTAP provided t o t a l scores and subscale scores for each of the three d i f f i c u l t y levels and each of the seven topics. For each subscale, the following were provided: subscale scores for each student, range of scores (including histograms), mean scores and subscale r e l i a b i l i t y (Hoyt's estimate of internal consistency). These data are summarized in Table 5.2. The program also provided co r r e l a t i o n c o e f f i c i e n t s for the relat i o n s h i p between the responses on each test item and the subscale and t o t a l test 1 1 4 scores, and gender. Correlations between subscale scores and t o t a l test scores were provided as well. Table 5.2 Range of Scores: Pretest and Posttest Pretest Posttest Min Max Mean r Min Max Mean r Level 1 7 21 16.5 0.81 8 21 17.7 0.81 Level 2 1 1 1 6.0 .70 1 1 5 7.7 .85 Level 3 0 4 2.1 .38 0 7 3.7 .58 Topics: Temp. Scales 1 6 4.4 .58 1 7 5.2 .83 Temp. Changes 1 6 4.7 .52 3 6 4.7 .40 Expansion 0 8 4.3 .76 1 9 5.3 .80 Matter & Heat 0 6 3.0 .32 1 5 3.4 .41 Composition of Heat 1 6 4.7 . 1 4 3 1 0 6.3 .51 Temp. & Heat 0 7 3.8 .49 1 7 4.3 .56 Movement of Heat 2 1 1 7.7 .87 5 1 4 9.5 .64 Total Test 8 36 24.6 0.87 1 3 43 29. 1 0.90 Three sets of school science marks were recorded. A mid-term mark had been provided to each student shortly before the observation period began. On the f i n a l day of the study the students wrote a unit test on heat and temperature which had been composed by the teacher. At the end of the term the teacher provided the f i n a l science mark assigned to each student. The teacher-made unit test and the posttest provided 1 15 two d i f f e r e n t measures of student knowledge at the end of the unit. The difference between the pretest and posttest scores provided a measure of the learning which occurred during the unit ( i . e . , unit learning). The coded class dialogue was summarized by tabulating and determining the r e l a t i v e frequencies of each of the various categories of dialogue, as described in Chapter I I I . The frequencies for males and females were compared to determine i f there were any gender differences in class p a r t i c i p a t i o n and/or student-teacher interactions. The number of times each individual student spoke during class dialogue was determined. Pretest and posttest scores were correlated with school science marks and with two other c h a r a c t e r i s t i c s which have been reported to be related to science learning ( i . e . , gender of student and the extent to which each student contributed to class discussions). To allow additional comparisons of the pretest and posttest responses, a c o r r e l a t i o n matrix of the subscale scores of both tests and pretest-posttest gain scores was prepared using SPSS:X (SPSS, Inc., 1983). Other measures included in the matrix were school science marks and two student c h a r a c t e r i s t i c s : gender and the measure of how many times the student spoke during class discussions ( t a l k ) . Analysis of variance and covariance were performed to further investigate s i g n i f i c a n t relationships i d e n t i f i e d by the c o r r e l a t i o n a l analysis, again using SPSS:X. The relationship between gender and talk suggested there might be a s i g n i f i c a n t interaction between these two factors. A two-way analysis of variance showed t h i s was not the case. Analysis of variance 1 16 also showed that the status of being a target student was not a s i g n i f i c a n t factor for any of the measures of learning. The relationship of gender and of talk on posttest scores was investigated using analysis of covariance, using the pretest as a covariate. The findings of the quantitive analysis must be interpreted very cautiously. There were only 23 students in the class--nine boys and 14 g i r l s . It i s impossible to make any strong claims on the basis of this small sample. However, the findings may be useful to the extent that they: 1. support or oppose any tentative conclusions derived from the tabulated data or the q u a l i t a t i v e data, and/or 2. suggest some alternative and/or additional findings which should be investigated by further studies. 5.2. Learning: Measures of Success The terms "learning" and "knowledge" can mean many things. Ausubel's d i s t i n c t i o n between rote and meaningful learning provides a basis for examining d i f f e r e n t kinds of learning and knowledge. Rote learning, for example, re s u l t s in knowledge that would allow a student to provide, verbatim, the textbook d e f i n i t i o n of a term ( i . e . , a rote response), but not necessarily to explain the term in his/her own words, identif y an example which would i l l u s t r a t e the key features of the term, or solve a problem which required an understanding of the term. Many of the student responses in t h i s study appeared to be rote responses. In such cases, i t was impossible to determine whether the response was meaningful to the student ( i . e . , 1 17 whether i t was i n t e l l i g i b l e , plausible or f r u i t f u l ) . A c r u c i a l d i s t i n c t i o n throughout this investigation has been the d i s t i n c t i o n between "learning" and "knowledge." Student knowledge can be considered to be the result of learning. For th i s study, i t i s also essential to separate a student's prior knowledge from the knowledge that was learned during the unit. Prior knowledge w i l l be assumed to be the result of prior learning. Knowledge at the end of the unit was not always the same as prior knowledge. Changes in knowledge w i l l be assumed to be the result of learning which occurred during the.unit ( i . e . , unit learning). As mentioned above, teachers are t y p i c a l l y in a position only to measure knowledge as assessed through tests such as the unit te s t . Measures such as t h i s do not separate prior knowledge from knowledge gained as a result of i n s t r u c t i o n . Nor do such measures always distinguish knowledge which has been learned by rote and is not i n t e l l i g i b l e to the students from knowledge which i s i n t e l l i g i b l e and possibly plausible and f r u i t f u l . To contrast prior knowledge with knowledge following instruction for individual students, t h i s analysis uses the difference between pretest and posttest scores. As these tests required students to apply their knowledge of heat and temperature concepts, they would have been unable to answer the questions using rote-learned d e f i n i t i o n s or facts which were not i n t e l l i g i b l e . Therefore, i t w i l l be assumed that responses on the posttest represent meaningful knowledge; that i s , knowledge which was not only i n t e l l i g i b l e and plausible, but probably f r u i t f u l as well. 1 18 Responses on the posttest were also contrasted with responses on the unit test and on written assignments to i d e n t i f y differences between rote and meaningful knowledge that would not be i d e n t i f i a b l e from the unit test or the assignments alone. As i s shown in Table 5.3, students who were successful learners according to one of the d e f i n i t i o n s of learning were not necessarily successful according to the others. Correlations between the various measures (Table 5.4) revealed that marks obtained on the unit test were more c l o s e l y related to Level 1 posttest subscale scores (r=0.590, p=0.003), than to Level 2 or 3 subscale scores (r=0.472 and 0.505, respectively; p=0.023 and 0.014, res p e c t i v e l y ) . Moreover, unit test marks were not s i g n i f i c a n t l y related to pretest/posttest gains (r = 0.230, p=0.29O. 5.2.1. Learning: Success in School Science In school, the marks attained by students on tests and assignments, and ultimately the f i n a l mark in the course provide a measure of success in learning. As was stated above, these marks more accurately r e f l e c t knowledge, rather than learning. They can not distinguish p r i o r knowledge from knowledge which has been learned as a result of i n s t r u c t i o n . They may not d i s t i n g u i s h knowledge which i s i n t e l l i g i b l e from knowledge which i s not. Seven students received marks of 80 percent or better on the unit t e s t . These students would thus be the top t h i r d of the c l a s s . Jane had the highest mark on a l l measures of school science achievement. Only three of the seven students were also in the top t h i r d on the posttest. Table 5.3 Student Posttest Scores and School Science Marks 119 Level Total Unit F i n a l Name 1 2 3 Score Test Mark Alan* 21 1 5 7 43 70% 52% Jane* 21 12 6 39 96 94 David 21 1 3 5 39 88 79 Joe* 20 14 4 38 78 77 Fred 21 13 3 37 75 76 Walter 20 9 6 35 86 75 Brian* 20 1 0 5 35 76 64 Mona 21 9 4 34 86 88 Melanie 20 8 4 32 88 73 Gordon* 1 6 9 6 31 60 38 Cindy 19 8 4 31 73 77 Laura 18 7 4 29 74 63 Lynne 19 7 3 29 71 72 Jack 13 1 1 3 27 68 60 Carolyn* 1 9 3 4 26 71 74 Marlene 1 6 8 1 25 59 70 Mary 18 5 2 25 46 66 Cathy* 1 7 3 4 24 80 62 Elle n 1 7 6 1 24 84 65 George 1 3 3 4 20 , 76 70 Susan* 1 6 2 0 18 59 55 Donna 1 3 3 1 17 22 24 *Target Students Alan, the student who scored highest on both the pretest (35) and posttest (43), got only 70 percent on the unit test (and only 52 percent as a f i n a l mark in the course). The reasons for Alan's lack of success in school science are undoubtedly complex. The teacher considered Alan to be a student of average a b i l i t y and with poor work habits. During class discussions she did not encourage him to question matters he did not understand. On two occasions he expressed an interest in pursuing a question, but the teacher did not follow up on his ideas. On those occasions, Alan was not heard from Table 5.4 Correlation Matrix Gender' Talk Pre1 Pre2 Pre3 Total Postl Post2 Post3 Total Gains Ga1n23 Unit Midt Talk -.510* PreLevI -.295 .394 PreLev2 -.305 .334 .204 PreLev3 -.259 .297 .121 .992** Pretest -.240 .331 .934** .157 .063 PostLevI -.155 .307 .704** .250 .196 .762** PostLev2 -.617** .642** .773** .232 .153 .772** .664** PostLev3 -.494* .467* .471* .218 .187 .480* .382 .544** Posttest -.499* .570** .809** .277 .206 .835** .859** .926** .672** Gain P/P -.506* .486* -.072 .241 .268 -.131 .300 .405 .426* .435 Gain 2/3 -.710** .654** .280 .249 .244 .102 .154 .623** .597** .525** .781** Unit Test -.195 .215 .526** .137 .086 .534** .590** .472* .505* .612** .230 .255 Midterm -.014 .169 .411 .018 -.019 .498* .594** .412 .292 .534** .147 .050 .708** Final Mk -.036 .127 .416* .029 -.000 .469* .606** .365 .232 .501* .135 .032 .790** .952** •Negative correlation favours males *p<.05 **p<.01 121 again that day. Alan was frequently late for cl a s s , and often needed a personal reminder to hand in an assignment. His assignments were often incomplete. His attendance was not good, and he made no evident e f f o r t to make up any work he missed, including two unit tests that were missed. Although Alan appeared to have the best understanding ( i . e . , the most meaningful knowledge or the most plausible knowledge) of the concepts of heat and temperature, he was not p a r t i c u l a r l y successful in school science (which measured both rote and meaningful knowledge, with the emphasis on the former). It seems unlikely that Alan would have gone out of his way to memorize terms, d e f i n i t i o n s , etc. On the heat and temperature unit test he lost marks for simple mistakes. He gave an inappropriate d e f i n i t i o n of temperature, did not draw a diagram that was required for one question, described conduction instead of convection, and only named two of the three types of heat transfer. Although he appeared to understand the concepts, he did not seem to remember s p e c i f i c d e t a i l s . Even so, his heat and temperature unit test mark was considerably higher than his f i n a l mark in science. Alan's f a i l u r e to complete assignments, to make up tests he missed and the lack of attention to d e t a i l s undoubtedly accounted for much of his lack of success in school sc ience. 5.2.2. Learning: Success on the Posttest Another measure of learning or knowledge was indicated by the scores obtained on the posttest. Students who had the highest scores on the posttest were those who were best able to apply their knowledge of heat and temperature concepts to 122 explain the problem situations posed on that t e s t . For purposes of t h i s analysis, i t w i l l be assumed that meaningful knowledge of heat and temperature concepts was related to success on the posttest. Knowledge which was rote learned, but not i n t e l l i g i b l e , could not have been used to answer questions on the posttest. It was assumed that students would only use concepts which were plausible to them to answer the questions. Therefore, posttest scores provided a measure of knowledge which was pl a u s i b l e . On the posttest seven students (Jane and six boys) had scores of 35 or more, of a possible 47. As already indicated, Alan had the highest score on the posttest, but his school science marks were far from high. 5.2.3. Learning; Gains in Scores from the Pretest to the Posttest To examine unit learning, a means of comparing p r i o r knowledge with knowledge at the end of the unit must be used. In t h i s study, unit learning was examined by comparing the pretest and posttest responses. A comparison of the means of subscale scores on the pretest and posttest (Table 5.2) reveals that o v e r a l l , students did do better on the posttest than they had done on the pretest. However, when individual scores were examined, three students ( a l l female) received lower scores on the posttest than they had on the pretest. For example, Cathy received a t o t a l of 28 on the pretest, and 24 on the posttest. One boy, Jack, received a lower score on the Level 1 subscale, but more than compensated for that loss by making substantial gains on the Level 2 and 3 subscales. One of two possible explanations for a decrease in subscale and/or t o t a l scores may 1 23 be pertinent. The pretest-posttest questions were scored on the basis of explanations provided for the various events. A student may have understood the phenomenon, but not given a f u l l explanation, either because (a) i t seemed so obvious to him/her that i t did not seem necessary to explain f u l l y , or (b) the student just did not take the time to write out a complete answer. In Jack's case, i t seems l i k e l y that one of these explanations was the cause for Jack's lower score on the Level 1 posttest questions. Another possible explanation for a decline in scores i s that, prior to ins t r u c t i o n , the student had an i n t u i t i v e understanding of the phenomenon, and provided that on the pretest. However, the student then became confused as a result of in s t r u c t i o n . He/she did not understand the school science explanation of the phenomenon, and was unable to provide a correct response on the posttest. Eleven students ( a l l nine of the boys, Jane and one other g i r l ) gained f i v e or more points from pretest to posttest. Only two of the 11 (Jane and one boy who was not a target student) were also among the top six.students on both the posttest and the unit t e s t . This i s not surprising, as the highest achieving students had l i t t l e or no room for improvement on Level 1 questions. When the pretest scores were examined according to le v e l s , the results indicated that the students did quite well on Level 1 items (mean score 16.5 of a possible 21), but not on Level 2 or 3 items (mean scores of 6.0 of a possible 15 and 2.1 of a possible 11, respectively). The very low r e l i a b i l i t y of the Level 3 subscale (.38) indicates r e l a t i v e l y inconsistent responses and suggests the students may not have understood 1 24 these items and were guessing or not responding much of the time. Further support for t h i s conclusion was obtained from two sources. The c o r r e l a t i o n matrix (Table 5.4) revealed that none of the other variables tested was s i g n i f i c a n t l y related to either the Level 2 or Level 3 pretest subscale scores. Level 1 pretest scores, to the contrary, were s i g n i f i c a n t l y related to almost a l l of the other variables. Furthermore, the analysis of covariance showed that for Level 1, but not Levels 2 or 3, the pretest accounted for a s i g n i f i c a n t amount of the variance in the respective posttest subscales. Compared to the pretest, Level 2 and 3 scores did improve on the posttest. More students received higher scores and the subscale r e l i a b i l i t i e s increased somewhat (from .70 to .85, and from .38 to .58, respectively), suggesting that the Level 2 posttest questions were answered more consistently than on the pretest, -and therefore indicating improved understanding. However, although Level 3 responses were more consistent than on the pretest, the consistency was s t i l l rather low, suggesting that most students did not understand the higher l e v e l quest ions. 5.2.4. Summary Tr a d i t i o n a l and commonly used measures of school "learning" do not in fact measure unit learning or gains in knowledge, but rather the extent of certain kinds of knowledge. A comparison of school science marks and pretest and posttest scores revealed that i t was not necessarily the students with the highest marks who showed the greatest gains in scores, or even the highest scores on the posttest. An examination of the teacher-made unit 1 25 test (Appendix D) reveals an emphasis on knowledge which could be rote learned, whereas the pretest and posttest required that students apply their knowledge to new situa t i o n s . When the class was divided into t h i r d s , f i r s t by posttest scores and then by science marks, some interesting contrasts appeared. When grouped according to the unit test: three of the seven highest achieving students were also in the top posttest group and two of the seven were in the lowest posttest group; f i v e of the eight lowest achieving students were also in the lowest posttest group. When grouped according to their f i n a l science marks: five of the seven top students were in the highest posttest group, but one was in the lowest posttest group; four of the eight lowest achieving students were also in the low posttest group. That i s , some of those who did poorly on the posttest did very well in school science, whereas one student who did very well on the posttest (Alan) barely passed the course. These findings suggest that some of those who were successful in school science must have r e l i e d on rote knowledge, and they were unable to apply that knowledge to the unknown situations presented on the posttest. Others, who may have understood the concepts, appeared unwilling to memorize school science facts and d e f i n i t i o n s which were meaningless to them. 5.3. C h a r a c t e r i s t i c s of Successful Learners The preceding section has examined the rel a t i o n s h i p between achievement in school science and scores on the pretest and . posttest. In this section, the relat i o n s h i p of those measures of learning and two other factors, p a r t i c i p a t i o n in class 126 dialogue and gender of student, w i l l be considered. Both of these factors have been reported in the l i t e r a t u r e to be related to achievement in science (they have also been reported to be related to one another). Talk, the measure of class p a r t i c i p a t i o n , consisted of a count of how many times the student talked during the class discussions. The duration of each instance of talking was not measured. However, i t was noted that those who spoke most often ( i . e . , the "talkers") also tended to speak at greater length than the less frequent speakers. P a r t i c i p a t i o n and gender w i l l each be examined in terms of the three d e f i n i t i o n s of successful learning. 5.3.1. Learning and P a r t i c i p a t i o n in Class Dialogue The data from the class discussions suggested that the most talk a t i v e students also tended to be the most successful students. A very interesting pattern emerged when talk was correlated with the learning measures (Table 5.4). Pretest scores and school science achievement were not s i g n i f i c a n t l y related to t a l k . However, a d i f f e r e n t picture emerged for the posttest scores. Total posttest scores and Level 2 and 3 subscale scores were s i g n i f i c a n t l y related to amount of talking (r=0.570, p=0.004; r=0.642, p=0.00l; and r=0.467, p=0.025, respectively). The Level 1 subscale score was not related to amount of t a l k . S i m i l a r l y , pretest/posttest gains were s i g n i f i c a n t l y related to amount of talking (r=0.486, p=0.0l8). As before, gains in the higher l e v e l subscales were most cl o s e l y related (r=0.654, p=0.00l for Levels 2 and 3 combined). The analysis of covariance indicated s i g n i f i c a n t differences only 127 for Level 3 by talk (Table 5.5: F=5.766, df=15, p=0.020). That i s , there was a s i g n i f i c a n t r e l a t i o n s h i p between p a r t i c i p a t i o n in class discussions and success on higher l e v e l questions on the posttest, as well as for gains in higher l e v e l questions from pretest to posttest. However, Level 1 and 2 posttest scores and school science achievement were not s i g n i f i c a n t l y d i f f e r e n t for talk (F=1.404, df=15, p=0.355, and F=2.825, df=15, P=0.103, respectively). The rela t i o n s h i p between p a r t i c i p a t i o n in class dialogue and gains in posttest higher l e v e l questions is i n t e r e s t i n g , and may warrant further study. If the s i g n i f i c a n t r e l a t i o n s h i p between p a r t i c i p a t i o n in class discussion and achievement on questions requiring higher l e v e l thinking can be replicated in other studies, i t could have important implications.for i n s t r u c t i o n . One p o s s i b i l i t y , of course, i s that students who are already capable of higher l e v e l thinking also tend to pa r t i c i p a t e more in class discussion. If so, i t could be that merely involving students in discussions w i l l not have any effect in increasing their higher l e v e l thinking a b i l i t i e s . Two other s i g n i f i c a n t relationships were found--talkers were more l i k e l y to be male (r=-0.51u, p=0.0l3) and they were more l i k e l y to be target students (r=0.572, p=0.004). These factors w i l l be examined in the next two sections. 5.3.2. Learning and Gender Research has shown that boys pa r t i c i p a t e in class a c t i v i t i e s and discussions to a greater extent than do g i r l s (Sadker and Sadker, 1985; Whyte, 1984). In mathematics classes, Becker (1981) found that boys were questioned more frequently 1 28 Source Table 5.5 Analysis of Covariance: Posttest by Talk with Pretest Sum of Squares df Mean Square Signif of F Total Test: Pretest Talk Residual Total 957.370 294.089 120.367 1371.826 1 1 5 6 22 957.370 19.606 20.061 62.356 47.722 0.977 0.000 0.552 Level 1: Pretest Talk Residual Total 124.198 98.589 28.082 250.870 1 1 5 6 22 124.198 6.573 4.680 it 11.403 26.536 1 .404 0.002 0.355 Level 2: Pretest Talk Residual Total 19 761 305.809 43.300 368.870 1 1 5 6 22 19.761 20.387 7.217 16.767 2.738 2.825 0. 149 0. 1 03 Level 3: Pretest Talk Residual Total 2.465 63.967 4.437 70.870 1 1 5 6 22 2.465 4.264 0.740 3.221 3.333 5.766 0.118 0.020 1 29 than g i r l s , and that they were asked more higher order questions. With respect to achievement, i t has been reported that boys outperform g i r l s on standardized tests of knowledge in the physical sciences (Erickson and Erickson, 1984; Kelly, 1978). Recent assessments of science in B r i t i s h Columbia have revealed that boys c l e a r l y outperform g i r l s on physical science questions and on higher l e v e l questions (Hobbs et a l . , 1979 and Taylor, 1982). G i r l s do as well as, or better than, boys on questions in the b i o l o g i c a l sciences and on lower l e v e l questions. Similar differences have been found world-wide (Kelly, 1978). However, gender differences are generally not found in school science achievement. For example, average marks obtained by male and female students writing the 1985 B r i t i s h Columbia p r o v i n c i a l science examinations were almost the same (Table 5\6, adapted from Kozlow, Note 1). Table 5.6 Results of the B r i t i s h Columbia Ministry Grade 12 Science Examinations, June 1985 Number of Students F i n a l Mean Score Male Female Male Female Biology 2353 4228 66. 1 66. 1 Chemistry 3098 21 56 69.8 68.3 Geology 331 191 64.6 62.7 Physics 271 0 669 69. 1 70.4 1 30 Two sources of data have been u t i l i z e d to examine the relat i o n s h i p between gender and learning about heat and temperature. The results of the dialogue analysis show the r e l a t i v e p a r t i c i p a t i o n in class discussion by males and females. School science achievement and pretest/posttest scores provide information about knowledge and learning. Although g i r l s made up 61 percent of the c l a s s , they only provided 42 percent of the student responses and one-third of the s t udent-initiated dialogue (Table 5.7). This i s p a r t i c u l a r l y s t r i k i n g as 30 percent of the female responses were from Jane. Only Joe talked more often than Jane. If Jane had not been in the c l a s s , the male-female differences would have been much greater. Moreover, only 39 percent of the teacher responses were directed to female students. Additional, but small, differences were revealed when the type of response was examined. A greater proportion of the g i r l s ' responses were correct, suggesting that g i r l s may be more reluctant to respond i f they are not certain they have a correct answer. Differences in teacher responses to males and females were less s t r i k i n g . Proportionally more of the teacher responses to g i r l s consisted of encouraging responses and explanations. The teacher was more l i k e l y to repeat a g i r l ' s response than a boy's (possibly because the g i r l s tend to be more soft-spoken?). Proportionally more of the teacher responses to boys consisted of t e l l i n g them their answer was wrong and providing information. The teacher was more l i k e l y to ignore a boy's response or redirect a question to another student when a boy responded. In addition, four of the five managerial responses were directed to boys. 1 3 1 Table 5.7 Tabulation of Student-Teacher Dialogue, by Gender, During 160 Minutes of Class Discussion Male Female Total Number of Students Students Called on by Teacher Student Responses to Questions Correct Answer Incorrect Answer P a r t i a l l y Correct Alternative Belief No Response TOTAL Student I n i t i a t e d Dialogue Question Information TOTAL Teacher Responses to Students Encourage, Explore Acknowledge Answer Wrong Answer Provide Information Explanation Demonstration Redirect Question Repeat Ignore or Dismiss Managerial TOTAL N % N % N 9 39. 1% 14 60.9% 23 43 58.1 31 41 .9 74 100 63.7 86 75.4 186 1 4 8.9 13 11.4 27 13 8.3 10 8.8 23 21 13.4 6 5.3 27 6 3.8 2 1 .8 8 157 100.0% 1 14 100.0% 271 37 55.2 12 36.4 49 30 44.8 20 60.6 50 67 100.0% 32 100.0% 99 100 33.9 71 38.2 171 65 22.0 44 23.7 109 1 1 3.7 2 1 .1 13 38 12.9 19 10.2 57 28 9.5 27 14.5 55 2 0.7 0 2 7 2.4 1 0.5 8 24 8.1 19 10.2 43 16 5.4 2 1 . 1 18 4 1 .4 1 0.5 5 295 100.0% 186 100.0% 481 1 32 None of these differences i s great, except for the o v e r a l l finding that far more responses came from and were directed to male students than from or to females. In addition to gender and class dialogue, the relationship between gender and the three d e f i n i t i o n s of learning was examined. School science achievement was not s i g n i f i c a n t l y d i f f e r e n t for males and females (Unit t e s t : F=0.831, df=1 , p=0.372; Midterm mark: F=0.004, df=1, p=0.951; F i n a l mark: F=0.028, df=1, p=0.869). Therefore, according to the f i r s t d e f i n i t i o n of successful learning, there were no s i g n i f i c a n t gender differences in learning. However, this was not the case for the other d e f i n i t i o n s . Boys c l e a r l y outperformed g i r l s , p a r t i c u l a r l y on the posttest. The analysis of covariance showed that boys' and g i r l s ' scores on the t o t a l posttest, and on the Level 2 and 3 subscales (but not Level 1 alone) were s i g n i f i c a n t l y d i f f e r e n t , with the pretest as a covariate (Table-5.8). As was mentioned e a r l i e r , three g i r l s had lower scores on the posttest than on the pretest. A s t r i k i n g pattern between gender, talking and pretest/postest gains was i d e n t i f i e d . It has been noted that there was a s i g n i f i c a n t relationship between gender and success on Levels 2 and 3 of the posttest. Eleven students gained four or more points in the Levels 2 and 3 combined subscale scores. Nine of those 11 were male; that i s , a l l of the males in the class were among the top half with respect to gains on Level 2 and 3 questions. The two females who showed the greatest gains were Jane and Cindy. Jane and Cindy were the two most talkative g i r l s in the c l a s s . Together they accounted for 43.1 percent of 1 33 Source Table 5.8 Analysis of Covariance: Posttest by Gender with Pretest Sum of Squares df Mean Square Signi f of F Total Test: Pretest Gender Residual Total 957.37,0 129.162 285.295 1371.826 1 1 20 22 957.370 129.162 14.265 62.356 67. 114 9.055 0.000 0.007 Level 1 : Pretest Gender Residual Total 124.198 0.763 125.908 250.870 1 1 20 22 124.198 0.763 6.295 1 1 .403 19.728 0.121 0.000 0.731 Level 2: Pretest Gender Residual Total 19 761 121.456 227.653 368.870 1 1 20 22 19.761 121.456 1 1 .383 16.767 1 .736 10.670 0.203 0.004 Level 3: Pretest Gender Residual Total 2.465 15.110 53.295 70.870 1 1 20 22 2.465 15.110 2.665 3.221 0.925 5.670 0.348 0.027 134 the talking by g i r l s (leaving 12 g i r l s responsible for the remaining 56.9 percent). However, as results in Table 5.9 reveal, there was a s i g n i f i c a n t main eff e c t for gender (F=14.956, df=1, p=0.0l2), but no effect for talk (F=5.536, df=15, p=0.034), and no s i g n i f i c a n t interaction between gender and talk (F=3.186, df=1 r p=0.134). The explanation for the lack of a s i g n i f i c a n t interaction may be the small numbers involved and the occurrence of two students who did not f i t the pattern. Jane was a frequent talker and a high achiever, and one boy, George, was neither. George was an ESL (English was his second language) student, and he only spoke when c a l l e d upon by the teacher. His overa l l achievement was low (Table 5.3). These two students were exceptions. With those two exceptions, the boys talked more than did the g i r l s , and six of the nine boys had higher posttest scores than a l l of the g i r l s except Jane (Figure 5.1). Boys and g i r l s did equally well in school science and on lower l e v e l questions, but boys outperformed g i r l s on higher l e v e l questions. Boys participated in class discussions more than did g i r l s . Gains in scores from pretest to posttest were greater for boys. Declines in scores occurred for three g i r l s (none of the boys had lower scores on the posttest than on the pretest). Findings such as these underline the importance of looking beyond s t a t i s t i c a l tests of s i g n i f i c a n c e , to examine the performance and c h a r a c t e r i s t i c s of individual students. 5.3.3. Learning and the Target Students There was concern that the fact of having been selected as a target student may have influenced learning. Two potential influences were i d e n t i f i e d . F i r s t , the target students were 1 35 . + — -+ — p o s t t e s t S c o r e 43 + 40 + 37 + 34 + * 31 + 28 + 25 + ** Cathy o George 22 + 19 + 16 + 13 + * _ + + + . 1 7 - + + + + + + -o A 1 an C a r o l y n Susan Jane o B r i a n o Jack o Gordon Joe o 13 19 25 3 1 37 4 3 49 55 Key: *Female "Mai e T a l k F i g u r e 5.1. P o s t t e s t Scores as a F u n c t i o n of T a l k , by Gender Table 5.9 Analysis of Variance: Posttest by Gender and Talk Sum of Mean Si g n i f . Source Squares df Square F of F Main Effects 1 279 .326 1 6 79. 958 7 .076 0. 020 Gender 169 .000 1 169. 000 1 4 .956 0. 012 Talk 938 .389 1 5 62. 559 5 .536 0. 034 2-Way Interaction: Gender X Talk 36 .000 1 36. 000 3 . 186 0. 1 34 Residual 56 .500 5 1 1 . 300 Total 1 371 .826 22 62. 356 interviewed about the pretest after i t was administered, and t h i s may have had some "treatment" e f f e c t . That i s , the students who discussed the pretest with the investigator may have remembered the topics and questions better than' they would have without the interview. If so, their posttest scores might have been somewhat i n f l a t e d . The second cause for concern derived from two of the c r i t e r i a used to select the target students. Four of the target students were chosen p a r t i a l l y because they were frequent talkers, and talkers were found to do better on the posttest. In addition, there were equal numbers of males and females among the target students, whereas only 40 percent of the t o t a l class was male. Again, males did better on the posttest. Analysis of variance revealed no s i g n i f i c a n t differences between the posttest scores of the target students and the other students (F=1.422, df=1, p=0.246). 1 37 5.3.4. Summary This section has examined the relat i o n s h i p between success in learning and two learner c h a r a c t e r i s t i c s : class p a r t i c i p a t i o n and gender. The effect of being a target student was also examined to ensure that t h i s had not unduly influenced learning. It was found that students who showed the greatest p a r t i c i p a t i o n in class dialogue were more l i k e l y to be successful on higher l e v e l posttest questions and to increase their scores from the pretest to the posttest. They were not more successful in school science. Male students performed s i g n i f i c a n t l y better than females on higher l e v e l posttest questions, but not on lower level posttest questions or in school science. Males participated in class discussions more frequently than females (except for Jane and George!). The next section w i l l focus on lack of success in learning. In Chapter IV, ten topics for which unit learning was not always successful, were i d e n t i f i e d . Each of these topics w i l l be examined in an attempt to identi f y some possible reasons for the persistance of alternative b e l i e f s . 5.4. Lack of Success in Learning: Persistant Alternative B e l i e f s Several topics which caused p a r t i c u l a r d i f f i c u l t i e s for the students were i d e n t i f i e d in the previous chapter. Alternative b e l i e f s about these topics persisted throughout and in spite of inst r u c t i o n , and they were expressed on the unit test and/or the posttest. 138 5.4.1. The Thermal Expansion of Matter at the P a r t i c l e Level The authors of the textbook (Schmid and Murphy, 1979) apparently recognized that many students believe that p a r t i c l e s expand, as they have stressed the idea that i t i s the spaces, not the p a r t i c l e s , that expand. The teacher also emphasized the idea that the spaces, not the p a r t i c l e s , expand. The students however, did not appear to see the two ideas as mutually exclusive. The expansion of p a r t i c l e s was discussed in class on two d i f f e r e n t days. On the f i r s t occasion, an investigation to measure temperature using a mercury thermometer was being discussed. Jane was asked what had happened to the mercury when the thermometer was put in b o i l i n g water. The discussion continued as follows: Jane: Umm, i t gets heated up and the p a r t i c l e s move faster and farther apart and so i t has to expand. Teacher: [writing on overhead projector] £).K. We'll put that down. When mercury i s warmed or heated up, I'm finding i t hard to hear [pause while teacher closes door to hallway]. Now, what did you say happens to the p a r t i c l e s , Jane? Jane: The p a r t i c l e s speed up and moved farther apart. Teacher: Are the p a r t i c l e s themselves getting bigger? Several students: No. Teacher: What's getting bigger? Students: The spaces. Jane: The spaces between the p a r t i c l e s . Teacher: O.K. So the spaces are getting bigger. What's happening to the quantity of mercury? The volume of i t ? Male student: Stays the same. Teacher: Lynne? Lynne: The volume's increasing. Teacher: The spaces are getting bigger. The p a r t i c l e s stay the 139 same size , but the spaces get bigger. The whole quantity has an increase in volume. Female student: The volume increases. Teacher: And what do we c a l l that? When we say the volume increases, the mercury? Student: Expands. Teacher: So i t sounds l i k e the p a r t i c l e s are getting bigger. They're not r e a l l y , of course. Just the whole blob of mercury in the bulb of your thermometer expands. Where does i t go? Jane: Rises up'the tube. [Teacher points to Susan] Susan: Goes up the tube. Fifteen minutes later the teacher performed the b a l l and ring demonstration for the clas s , and asked: Teacher: What's happening to the p a r t i c l e s inside the b a l l as I heat i t ? Several students: Expands Teacher: Careful now. Listen to the question. What happens to the p a r t i c l e s ? Susan? Susan: The p a r t i c l e s are expanding. [Several hands raised] Teacher: Are they? Students: Nooo Teacher: Jane? Jane: They're speeding up and moving apart. Teacher: How do they speed up? What kind of energy are they gaining? Students: Heat/Mechanical Teacher: They're moving farther apart and what's expanding? Students: The spaces Teacher: The spaces and therefore the whole b a l l . . . 140 In the f i r s t segment, while discussing a mercury thermometer, the students who contributed to the discussion seemed quite clear that the p a r t i c l e s do not expand. Jane provided her opinion on two occasions—when the teacher asked Susan to respond, Susan gave the answer Jane had just c a l l e d out. Although the students seemed to agree that l i q u i d mercury p a r t i c l e s did not expand, a few minutes later many of them said that the p a r t i c l e s of metal in the b a l l - r i n g apparatus would expand. For example, although Susan had been paying attention during the e a r l i e r discussion, she replied that the metal p a r t i c l e s were expanding. The teacher then redirected the question to Jane who gave the desired response. Susan's alternative b e l i e f was not dealt with.directly. This was one of several times that a question was redirected to Jane after another student had responded with an alternative b e l i e f . In class three days l a t e r , Brian, a student who had talked about p a r t i c l e s expanding during the pretest interview, was asked i f p a r t i c l e s get bigger when a metal s t r i p i s heated. Brian said he wasn't sure. The discussion continued: Teacher: You're not sure. If the p a r t i c l e s got bigger, how would they get bigger? Brian: They would expand. Teacher: The p a r t i c l e s would expand. Now i f something expands, there has to be something pushing i t to make i t get bigger—something pushing harder to make i t get bigger, right? What i s there inside a p a r t i c l e to make i t get bigger? Brian: There i s thi n g s — s m a l l e r things. Teacher: 0. K., but according to the p a r t i c l e model, the p a r t i c l e ' s the smallest thing. Now, i f you want to c a l l p a r t i c l e s atoms, there are things inside atoms c a l l e d 141 neutrons, protons and electrons, that we saw in chemistry. But then we wouldn't use i t ' a s a p a r t i c l e model. So i f you're going to c a l l atoms p a r t i c l e s , then you would have to be looking at the properties or c h a r a c t e r i s t i c s of these, and i t might be quite complex i f you start looking at the inside of p a r t i c l e s as the smallest part of matter. REMEMBER, THIS IS NOT REALITY, IT'S A MODEL--a model we use to explaing how things happen--like building a model airplane—you're not going to f l y that airplane. So i t ' s a model that approximates the real thing, but i t ' s never going to be r e a l . After t h i s rather lengthy, complicated explanation, the teacher turned to another student to answer a question on an e n t i r e l y d i f f e r e n t t o p i c . Brian's uncertainty was not explored and dealt with. In the assigned questions for the chapter and on the posttest, both Brian and Susan said that p a r t i c l e s expand. For example, one assigned question asked how adding more heat energy to the a i r in a balloon would change the force of a i r on the inside of the balloon. Brian responded, "It expands the p a r t i c l e s making more room." When assignments were returned to students, i t was indicated on their papers that such statements were not correct. Yet, on the posttest Brian said that heat causes pipes to expand because " i t expands their p a r t i c l e s . " On another assigned question, Susan said that when l i q u i d in a tube is heated and rises up the tube, i t is "because of expanding p a r t i c l e s . " Thus, although a l l of the students apparently accepted the idea that the p a r t i c l e s move farther apart (and/or a l t e r n a t i v e l y , that the spaces expand) when matter i s heated, five students were so convinced that p a r t i c l e s expand that they stated t h i s on the posttest. We have no idea how many other students may have retained the same b e l i e f , but did not mention 1 42 i t . We can only speculate as to why the students persisted in t h i s b e l i e f . Three of the f i v e had been i d e n t i f i e d by the teacher as weak students who had d i f f i c u l t y in science. Susan and two other g i r l s may have simply been so confused that they were not aware of any contradictions. A fourth g i r l was i d e n t i f i e d as a student of average a b i l i t y . She was not one of the target students and did not p a r t i c i p a t e in class discussions, so i t was impossible to even speculate as to why she may have had d i f f i c u l t y with t h i s idea. Brian's b e l i e f s are somewhat better known. Brian was one of two boys who challenged the p a r t i c l e model used in the text. The model is summarized as follows: In your l a s t science course, you used the p a r t i c l e model of matter. According to t h i s model, a l l materials are c o l l e c t i o n s of very tiny p a r t i c l e s that are always moving as shown in F i g . 3. The p a r t i c l e s of a material stay together because they are always moving in a l l d i r e c t i o n s . The spaces between the p a r t i c l e s contain nothing; i t i s a perfect vacuum. (Schmid and Murphy, 1979, pp. 350 and 352) Brian and Joe p e r s i s t e n t l y argued that atoms and molecules are not single p a r t i c l e s and are not the smallest p a r t i c l e s of matter. This issue p a r t i c u l a r l y surfaced during a discussion of the idea that heat energy i s the energy of p a r t i c l e s (one of the key points made in the textbook). Students were to l d that, unlike other energy transformations, there was no heat loss due to c o l l i s i o n s among p a r t i c l e s . As was pointed out in- the previous chapter, the teachers' guide warns the teacher that problems may occur with t h i s model. The following quotation from the teachers' guide bears repeating, as the teacher t r i e d to present t h i s idea to Brian and Joe during t h i s discussion. 143 The statement that gas p a r t i c l e s have nothing smaller to give their energy to i s a s i m p l i f i c a t i o n of the facts. Thinking students may know that many p a r t i c l e s are made of atoms which, in fact, are made of smaller p a r t i c l e s s t i l l . ...However, because the number of component parts of a p a r t i c l e i s small (compared to the number of component p a r t i c l e s of a macroscopic object) energy can be given back by the component parts to the p a r t i c l e as a whole. In contrast, the chance of energy being given back to a large object by i t s p a r t i c l e s i s p r a c t i c a l l y n i l . (Schmid et a l . , 1980, p. 106) When the teacher t r i e d to present t h i s view i t simply was not accepted by either Brian or Joe. Both "knew" that neither an atom nor a molecule consists of a single p a r t i c l e . In the dialogue between Brian and the teacher quoted e a r l i e r , Brian said there were smaller .things within p a r t i c l e s . It i s possible that Brian believed that sub-atomic p a r t i c l e s must also be able to move apart, thereby causing the atom to expand. Although there was no opportunity to v e r i f y t h i s p o s s i b i l i t y , i t would account for Brian's persistence in the idea that particles-* expand. When learning and knowledge were discussed e a r l i e r in t h i s chapter, i t was pointed out that one student might hold a b e l i e f that was d i f f e r e n t than his/her knowledge of school science. If a student were to give a "correct" answer on the unit test which was d i f f e r e n t from an answer given on the posttest, i t may indicate that the student did not r e a l l y believe the "correct" answer. For example, on the unit test both Susan and Brian drew diagrams to show the difference between a bar of iron at room temperature and one at 100°C. Both drew the p a r t i c l e s the same size at both temperatures, and showed the p a r t i c l e s farther apart in the bar at the hotter temperature. However, on the posttest (written during the same science period), both Susan 144 and Brian said that p a r t i c l e s expand when matter i s heated. 5.4.2. The Nature and Extent of the Spaces Between the  Pa r t i c l e s of Matter Some students did not di s t i n g u i s h between matter and p a r t i c l e s . B e l i e f s expressed by Cathy i l l u s t r a t e the d i f f i c u l t i e s that may arise i f t h i s d i s t i n c t i o n i s not made. For example, she wrote that when heated, "water looks as i f i t expands. Actually only the spaces are." The posttest revealed that Cathy s t i l l believed that "matter" did not include the spaces between the p a r t i c l e s , but only the p a r t i c l e s themselves. Carolyn's b e l i e f that heat could be transferred through a glass wall by a i r p a r t i c l e s also reveals a lack of understanding of the nature of the spaces between the p a r t i c l e s . These ideas were not discussed in class, presumably because i t was assumed that the students had an accurate understanding of the particulate nature of matter. 5.4.3. The Nature of Heat and the Difference Between Heat and  Temperature An entire chapter i s devoted to distinguishing between heat and temperature based on the findings of two major investigations. Unfortunately, the questions i d e n t i f i e d for the investigations do not make the aim of distinguishing heat and temperature clear to the student. In the textbook, "Questions to be investigated" are i d e n t i f i e d for each investigation. The students had been told that those questions indicated the purpose/s of the investigations. The investigation e n t i t l e d , "The heat energy and temperature of di f f e r e n t objects" (1.42), introduces the 1 45 chapter. The major aim of this investigation is to demonstrate that temperature i s not a direc t measure of heat energy. This experiment uses calorimetry to show that when heat is transferred from one substance to another, the temperature change varies for d i f f e r e n t substances. Students learn that the type of material and the amount of material both a f f e c t the size of the temperature change. In the teachers' guide, the following overview is given for the investigation.: "A series of controlled experiments show that the heat energy of an object (as measured by i t s effect on a fixed mass of water) depends on i t s mass and i t s material as well as i t s temperature" (Schmid et a l . , 1980, p. 121). Sim i l a r l y , in the student text (Schmid and Murphy, 1979, p. 126) the introduction t e l l s the students that the investigation w i l l show that heat and temperature are di f f e r e n t , but that an object's temperature can t e l l us something about i t s heat energy. In spite of th i s o v e r a l l aim, the i d e n t i f i e d questions to be investigated are: 1) If two objects with the same mass are made of the same material, which has more heat energy--the one with the higher temperature or the one with the lower temperature? 2) If two objects made of the same material have the same temperature, which has more heat energy--the one with more mass or the one with less mass? 3) If two objects with the same mass have the same temperature do they have the same amount of heat energy i f they are made of d i f f e r e n t materials? (Schmid and Murphy, 1979, p. 126) At no time are the students asked to explain how these observations show that heat and temperature d i f f e r . It i s apparently assumed that they w i l l recognize the -difference i f they are able to answer the three questions. As we have seen, 146 thi s was not so. Because the questions were used to indicate the purpose of the investigation, there i s no doubt that they, not the introductory statement, would be given primary emphasis. Thus, i t should not be surprising that the heat-temperature d i s t i n c t i o n did not surface during class discussion. Indeed, we may conclude that t h i s was not the teacher's view of the importance of the investigation either. On the unit test, one question dealt with t h i s investigation. That question was, " L i s t three factors which a f f e c t the heat energy of an object." Therefore, i t appears that neither teacher nor students viewed the heat-temperature d i s t i n c t i o n as the purpose of the investigation. The investigation i s followed by a reading section in the textbook, "Heat Energy and Temperature," which provides an explanation of the d i s t i n c t i o n in terms of p a r t i c l e s . This reading and i t s questions were assigned but they were never discussed in c l a s s . The questions did not ask students to explain the d i s t i n c t i o n between heat and temperature. The second investigation, "Heat and temperature in phase changes," caused the most d i f f i c u l t y . This investigation w i l l be discussed in more d e t a i l in a l a t e r section. However, one of the assigned questions i s important for the heat and temperature d i s t i n c t i o n . The question asked: During this Investigation, you added heat energy steadily, but the temperature did not go up st e a d i l y . How does th i s Investigation show that heat energy and temperature are not the same thing? (Schmid and Murphy, 1979, p. 138) Eleven of the 17 students who handed in this assignment had the correct answer for th i s question in their notebooks. Yet, few, i f any, appeared to understand the implications of the answer. 147 The answer was not i n t e l l i g i b l e to many. When the questions were taken up in cl a s s , the following dialogue occurred: Teacher: [reading] "During t h i s Investigation, you added heat energy steadily, but the temperature did not go up ste a d i l y . " At the beginning and at the end i t l e v e l l e d o f f . "How does th i s Investigation show that heat energy and temperature are not the same thing?" That's a d i f f i c u l t question! "How does th i s Investigation show?" This i s the question Lynne had e a r l i e r . How does i t show that the two are not the same thing? Jane: This investigation shows that heat energy and temperature are d i f f e r e n t , because i f they were the same, the temperature would have increased at the same rate as heat energy. Teacher: Mhmm. If they were applying heat energy and the heat energy was increasing, the temperature'd have gone straight up. The heat energy, i f we could've read i t , would have gone straight up. The temperature went l i k e t h i s - - i t l e v e l l e d o f f . That's a good answer. Less than one minute was spent on t h i s question. Jane was asked to give her answer. The teacher acknowledged that i t was a d i f f i c u l t question, but she did not ask the students i f there were any questions, not did she ask anyone to explain the answer in his/her own words. She proceeded d i r e c t l y to the next question. 5.4.4. The Type of Material as a Factor Related to the Heat Energy ( i . e . , Internal Energy) of Matter Many students believed that the s p e c i f i c heat capacity of more dense matter exceeded that of less dense matter (although the term " s p e c i f i c heat capacity" was not used). This idea would have been addressed i f the f i n a l part of investigation 1.42 (described in the preceding section) had not been omitted. The experiment consists of three parts and would need at least two periods to complete in f u l l . Each of the questions i d e n t i f i e d previously refers to one part of the experiment. The 148 f i r s t part determines the temperature change in 100 ml of room temperature water when two equal masses of metal are added. I n i t i a l l y , one piece of metal i s at 50°C and the other at 100°C. Part 2 compares the temperature change that results when 50g and I00g masses at 100°C are each added to 100 ml of room temperature water. Part 3 compares equal masses of two di f f e r e n t metals and of water, a l l at 100°C, added to 100 ml of room temperature water. The teacher reduced the time required by having d i f f e r e n t groups of students work with d i f f e r e n t types of metal for part 2, and omitting part 3. This omission meant that the students did not have an opportunity to compare the change caused by the metals with that caused by an equal mass of hot water. Had they done so, they would have seen that the s p e c i f i c heat capacity of water i s much greater than that of metal. The observed temperature changes for the two metals, zinc and n i c k e l , were very small. In fact, when discussing the temperature change for the two metals, the teacher asked, " A l l rig h t . Read me the statements you made please, for d i f f e r e n t matter at the same temperature." Joe responded, "Different matter at the same temperature i f i t ' s denser has more heat energy," whereupon the teacher repl i e d , "Good." In fact, there is a tendancy for a rela t i o n s h i p between density and s p e c i f i c heat capacity, but the relationship i s inverse, rather than d i r e c t . The students were then directed to do the assigned questions, the f i r s t of which asked: 1 49 Which has more heat energy--a) 1 kilogram of water at 30°C or 1 kilogram of water at 70°C? b) 1 kilogram of water at 30°C or 1 gram of water at 30°C? c) 1 kilogram of water at 30°C or 1 kilogram of iron at 30°C? (Schmid and Murphy, 1979, p. 129) Everyone answered "a)" co r r e c t l y ; a l l but one student answered "b)" c o r r e c t l y ; and only one student answered " c ) " c o r r e c t l y . That i s , a l l but one student believed that iron, which is more dense than water has more heat energy than water. This answer fr i s consistent with Joe's statement given above, and approved by the teacher. Either the teacher did not l i s t e n c a r e f u l l y to Joe's answer, or she did not recognize that less dense materials tend to have a greater s p e c i f i c heat capacity than more dense materials. Perhaps the confusion about this r e l a t i o n s h i p would have been avoided altogether had the students not omitted the th i r d part of the investigation. The teachers' guide notes that i t i s important for students to add the hot water to the cold to demonstrate that i t takes far more heat energy to raise the temperature of water than i t does to raise the temperature of metal. The students did not do the one experiment that would have shown them that one kilogram of water at 30°C does have more heat energy than one kilogram of iron at 30°C. Density was again dealt with when the chapter review questions were being taken up. The following question was discussed: If two objects have the same mass and the same temperature, but one i s made of water and the other i s made of lead, then the one made of has more heat energy. Melanie: Lead. Several students: Nooo. 1 50 Male student: That's denser, so i t should be. Teacher: What's the problem using density? Jane: You have the same mass of each of them, so 50g of lead and 50g of water, and the water i s going to have more heat energy because the p a r t i c l e s are moving faster and so they have more mechanical energy. In spite of Jane's explanation, many students continued to believe that denser matter has more heat energy than less dense matter. It i s interesting to note that i f s p e c i f i c heat were defined in terms of volume, rather than mass, the students' i n t u i t i o n s about the effect of density would be more accurate. As many students did appear to think of quantity in terms of volume (a quantity which can be seen), rather than mass, their i n t u i t i o n s may have been more l o g i c a l than they seem. The implications of t h i s way of thinking of quantity may warrant further investigation. Another factor may also be relevant in this p a r t i c u l a r instance. Jane was frequently c a l l e d upon to explain d i f f i c u l t concepts or answer d i f f i c u l t questions. Some of the students may not have understood Jane's explanation and therefore not remembered what she said. Some students may have become accustomed to Jane giving complex answers and made no attempt to follow her explanation. 5.4.5. When Matter i s Heated, the Rate of Temperature Change is Not Constant When a Change of Phase Occurs Many d i f f i c u l t i e s arose with the phase change investigation (1.45). The investigation involved heating ice u n t i l the water reached the b o i l i n g point. The temperature of the water was recorded every two minutes. F i r s t of a l l , neither the text nor the teacher t o l d the students that the horizontal scale (time) 151 represented the increase in the amount of heat supplied to the water. The students' responses to the questions reveal that they assumed i t was the temperature scale that represented the amount of heat. For example, in her conclusion Jane wrote that r a i s i n g the temperature of the l i q u i d water from 0° to 100°C took more heat energy than b o i l i n g away the water. This idea was probably reinforced by the teacher, who said at the beginning of the discussion, ...we're not measuring heat energy d i r e c t l y . We can't measure those l i t t l e p a r t i c l e s moving around and sum up the mechanical energy to give us heat energy d i r e c t l y . What we do i s measure i t i n d i r e c t l y by measuring the temperature, hotness or coldness. This misunderstanding was not detected during the discussion. Some of the students were asked to read their conclusions ( i . e . , their answers to the questions to be investigated). One boy gave an incorrect answer to one question (he said that r a i s i n g the temperature of water from 0°C to 100°C takes more heat energy than b o i l i n g away the water). The teacher did not notice the error (the boy was one of the students she considered to be very b r i g h t ) . Alan then asked i f the temperature of water vapour could exceed 100°C, and the teacher said no. This was a question Alan and another boy had raised while doing an e a r l i e r investigation (the mercury thermometer) and i t had not been resolved at that time. Brian also joined the discussion. Alan next asked i f ice could not get colder than 0°, arguing that lowering the temperature, would lower the heat energy. The teacher responded that t h e o r e t i c a l l y i t should be possible, but in fact i t was not. The teacher was mistaken on this as well, but she was unwilling to reconsider her p o s i t i o n . At t h i s point 1 52 Jane interjected, challenging the incorrect answer given e a r l i e r and Alan's concern was forgotten. The teacher accepted the correction by Jane. Additional problems arose with respect to the temperature plateau which occurred as the ice was melting. The investigation had been performed as a demonstration by Alan and Joe, with Jane recording the data on an overhead projector. A l l students copied the data and completed a laboratory report. Jane obviously expected the temperature to increase at a constant rate. When the ice had melted and the rate increased sharply, Jane would not accept the res u l t s . She was more w i l l i n g to believe that the boys had made an error than to abandon her alternative b e l i e f . In the end she inserted additional readings to the data to make the changes in the slope less conspicuous (for more d e t a i l s on the discussion which took place among Jane, Joe and Alan, see Appendix E). In t h i s s i t u a t i o n , l i k e the grade four children studied by Stavy and Berkowitz (1980), Jane was unwilling to accept results which were contrary to her prior b e l i e f s . During the discussion of t h i s investigation the teacher apparently assumed there was a d i s t i n c t plateau on the graphs. As we have already noted, the teachers' guide indicates that the temperature would not be constant during the change from s o l i d to l i q u i d phase because the rapid heating prevents the system from reaching an equilibrium. The teacher had not examined either the data or the graphs and i n s i s t e d that the temperature did not increase before the ice . had melted. Brian t r i e d to argue about t h i s , but the teacher was not w i l l i n g to discuss i t 153 further. The discussion l e f t the students with two dilemmas. F i r s t , the teacher i n s i s t e d there was no increase in temperature while the ice was melting, yet the data indicated that there had been an increase. Secondly, some of the students were confident that the teacher was wrong about the temperature of ice and of water vapour being constant. 5.4.6. The Nature of Cold and the Difference Between Heat and'  Cold When the pre/posttest was being p i l o t - t e s t e d , one student came to a question which referred to cold, and said to the investigator, "I thought you said t h i s test was about heat." I replied, "It i s . " The student then said, "But t h i s question i s about cold." Daily conversation about heat and cold not only refers to heat as i f i t were a f l u i d substance, but in addition, refers to cold as i f i t were another f l u i d substance. "Hot" is the sensation of something that feels hot, r e l a t i v e to our body surface. "Cold" i s the sensation of something that feels cold, r e l a t i v e to our body surface. H i s t o r i c a l l y , we find that early investigators of heat and temperature phenomena also considered "cold" to be something d i s t i n c t from "heat" (Wiser and Carey, 1983). Posttest explanations of why the metal blade of a shovel f e l t cooler than the wooden handle revealed that many of the students in the class assumed that cold i s a d i f f e r e n t thermal entity than heat. Neither the textbook nor the teacher appear to have recognized t h i s idea as a possible alternative b e l i e f , and consequently, the idea was never discussed. Moreover, the d e f i n i t i o n of temperature as "hotness or coldness" may have been 1 54 perceived as a confirmation of the existance of the two thermal e n t i t i e s . On three occasions, the idea of cooling (as opposed to heating) was discussed in cla s s . The f i r s t instance was when the teacher was taking up the assigned questions from the phase change investigation. One question asked why you fee l cool when perspiration evaporates. One g i r l r eplied, "You feel cool because your perspiration evaporates and you're losing heat energy." The teacher responded, "In order for evaporation to occur, we have to use heat energy. Heat energy i s supplied by your body and you fee l cooler." The second occasion was when conduction was being discussed. The teacher asked why a metal faucet" f e l t colder than the table top. Alan responded, "It's taking our heat." The teacher accepted this response and went on to a d i f f e r e n t topic. Apparently many of the students did not recognize the implications of perspiration or the faucet "taking our heat." They did not relate cooling to a loss of heat. In another instance, the teacher performed a demonstration of conduction. She set a bunsen burner under a paper cup f i l l e d with water and the cup did not catch f i r e . When she put the burner under an empty paper cup, the cup did catch f i r e . The teacher asked why the cup with the water did not burn. This discussion went as follows: Jane: The water i s cooling i t o f f . Teacher: Heat energy i s coming through the bottom, isn't i t ? Jane: Yeah, but the water i s cooling i t from the top, too, so a l l the coolness from the water reaches through the paper, so i t ' s s t i l l not gonna burn, 'cause.it can't reach i t s kindling temperature. 155 Teacher: What's happening to the heat that i s being applied to the bottom? Male student: It's making the water warmer. Later, during the discussion of conduction, the teacher said: ...the bottom of [the class handout on conduction] t e l l s you something very important. Usually we think of conduction as transferring heat to warm something up. What sort of [examples] do you know of where you cool something down by conduction? Jack: Fridge. Joe: Umm, where you pour cold water, things l i k e that. Teacher: That's true, because once you pour cold water over you, you reduce the heat energy from your body. Alan: Radiator. [This response was ignored] Jane: Ice in a drink. It can be seen that i f a student believed that heat and cold were d i f f e r e n t , these discussions would not necessarily refute that b e l i e f . As was noted in the previous chapter, both Jane and Joe, two very capable students, expressed the be l i e f that cold was d i s t i n c t from heat on the posttest. In the preceding section, a si t u a t i o n was described wherein Jane rejected very strong evidence that another of her alternative b e l i e f s was incorrect. In t h i s instance, nothing was said during the class discussion that would have suggested to Jane that her b e l i e f about cold was inconsistent with school science. 5.4.7. The Ef f e c t s of Heating on Different Kinds of Matter It has already been noted that when an open question of the sort, "What happens when X i s heated?" was asked, the students often responded inappropriately. For example, students replied that a paper c l i p would melt, although the topic being discussed 1 56 was conduction. E a r l i e r that day, the teacher had demonstrated the bimetallic s t r i p and had asked what would happen i f she were to continue heating the s t r i p . Joe replied, "It should melt." The teacher responded, "Oho! Before i t melts. We're not going to l e t i t melt." 'Joe then suggested the s t r i p would straighten out because some metals expand more rapidly than others and the metal which expanded more slowly would eventually catch up. At that point, another boy (one considered to be a good student), raised his hand and then predicted, "The brass would melt before the steel would melt." Although the teacher had indicated that melting was not relevant, the students persisted in coming back to i t . After reviewing a l l such inappropriate responses, i t appeared that the students tended to respond with an observation that could be seen. In p a r t i c u l a r , a change of phase was often predicted. That i s , i f the object were s o l i d , such as ice or metal, they tended to say i t would melt. A l i q u i d in an open container usually boiled. Expansion and r i s i n g were also common responses. If a l i q u i d in a closed container were being heated, the students usually said either i t expanded or i t rose. Gases, such as a i r , r i s e when they are heated. Each of these responses was an isolated incident, at no time were a l l of these phenomena presented together. Neither the book, nor the teacher pointed out that when matter i s heated (for example, during the phase change experiment or when heat transfer was being investigated) and when the mechanical energy of the p a r t i c l e s increases, several things happen. The temperature of a s o l i d increases u n t i l i t reaches the melting point, and the matter expands as i t s p a r t i c l e s gain mechanical energy (unless i t is i c e ! ) . As 157 the s o l i d melts, i t s temperature remains r e l a t i v e l y constant. When a l l of the substance has melted, the temperature increases more rapidly as heat energy i s no longer being used to change the substance from a s o l i d to a l i q u i d . At the same time as the l i q u i d i s getting hotter, i t continues to expand, u n t i l i t reaches the b o i l i n g point, etc., etc. Perhaps i f the class discussion had pulled a l l of these ideas together i t would have helped some students. Instead, each was treated in i s o l a t i o n , and the students were l e f t to put the ideas together themselves. 5.4.8. How Conduction Occurs at the P a r t i c l e Level Many students were able to provide reasonable explanations of conduction, based on the p a r t i c l e model, on the unit test. However, b e l i e f s expressed on the posttest revealed that many of the students did not understand the. implications of the transfer of mechanical energy by c o l l i s i o n s among p a r t i c l e s . For example, students for whom thi s idea was f r u i t f u l would have known that a shovel l e f t outdoors overnight would have been the same temperature as the a i r temperature. Only Alan answered that question c o r r e c t l y . Some alternative b e l i e f s were revealed by the d e f i n i t i o n s provided on the posttest. For example, Carolyn r e p l i e d : The p a r t i c l e s of two objects touching a t t r a c t each other and the heat of the hotter object is attracted. In th i s way the heat energy i s transferred. The p a r t i c l e s never move out of their places in conduction. Metals conduct better than non-metals. The teacher had stressed two features which distinguish conduction from other types of heat transfer: heat moves from matter with more mechanical energy to matter with less mechanical energy and the p a r t i c l e s stay in one place. The 158 teacher concentrated on the mechanical energy of the p a r t i c l e s , rather than emphasizing that i t was a difference in the temperature of the objects that was important. In the textbook, conduction i s introduced as follows: Hot objects cool down because they give heat energy to the cooler objects around them. Cold objects warm up because they gain heat energy from the hotter objects around them. When a hotter object gives heat energy to a colder object, we say that heat energy i s being transferred from the hotter object to the colder one. (Schmid and Murphy, 1979, p. 140) This description i s in terms of concrete objects and would probably be more meaningful to most students than was the teacher's explanation, expressed in terms of the mechanical energy. 5.4.9. The E f f e c t of the Type of Material on the Rate at Which  Heat i s Transferred by Conduction An e a r l i e r section (5.4.4) discussed the belief that density i s the property of'matter which affects the amount of heat energy in an object. This section w i l l focus on the rate of heat transfer by conduction in d i f f e r e n t types of material. Some students believed that less dense so l i d s conduct heat more rapidly than more dense s o l i d s , while others believed the opposite. Those who predicted that a less dense object would conduct more rapidly may have had one of two alternative b e l i e f s . The f i r s t i s the idea that heat moves between p a r t i c l e s of matter and hence travels faster when i t has more room. This idea was expressed by Carolyn on the pretest and by Susan and three others g i r l s on the posttest. (A sixth g i r l spoke of heat p a r t i c l e s moving through matter.) The other a l t e r n a t i v e b e l i e f was expressed by Brian during the interview. 159 He said that when p a r t i c l e s were farther apart they had more room to move around and thus they were able to speed up more quickly in less dense matter. During the class discussion, Gordon's explanation of conduction also dealt with why d i f f e r e n t materials conduct heat energy at d i f f e r e n t rates: ...heat conducts through d i f f e r e n t p a r t i c l e s [pauses-teacher says, "Uhuh"] and also at d i f f e r e n t speeds, and penetrates these lev e l s by, ummm, one molecule passes the heat, that's based on the model, and then i t h i t s that one and i t gets the heat and then i t h i t s that one and i t gets the heat and they carry on. That's why the a i r , since there's not enough, as many p a r t i c l e s as s o l i d , heat passes through slower. The students a l l recognized that conduction does occur at d i f f e r e n t rates in d i f f e r e n t materials and they answered assigned questions which dealt with everyday applications of th i s p r i n c i p l e . For example, the students recognized that cooking pans usually do not have metal handles, because metal i s a good conductor. Although the students a l l answered such questions c o r r e c t l y , many of them were unable to explain these phenomena in terms of the mechanical energy of the p a r t i c l e s . 5.4.10. How Heat is Transferred by Radiation Radiation was dealt with very s u p e r f i c i a l l y . No reading or questions were assigned. The class discussion concentrated on factors which influence absorption and r e f l e c t i o n of radiant energy. The greenhouse ef f e c t and the idea that hotter objects radiate more heat energy than cooler objects were discussed b r i e f l y . The unit test included a question addressing the l a t t e r idea and which was answered co r r e c t l y by 13 of the 23 students. The mechanism whereby radiant heat energy i s transferred was not addressed at any time. 160 5.5. Summary This chapter has focussed on "learning." It began by examining three alternative measures of learning: school science marks, posttest scores and pretest/posttest gains. It was shown that individual students demonstrated varying degrees of success in learning according to the d i f f e r e n t d e f i n i t i o n s . Quantitative analysis showed that gender of student and class p a r t i c i p a t i o n were both related to some, but not a l l , measures of learning. Students who were most successful on the higher l e v e l items of the posttest tended to pa r t i c i p a t e more in class discussions, and were more l i k e l y to be male. However, boys and g i r l s school science marks were not s i g n i f i c a n t l y d i f f e r e n t . Tabulations of the di f f e r e n t categories of dialogue showed more frequent student-teacher interactions for boys than for g i r l s . F i n a l l y , some examples of lack of success in learning were examined. Ten topics were i d e n t i f i e d as posing p a r t i c u l a r problems for students. Alternative b e l i e f s about these topics were i d e n t i f i e d and factors which may have been related to these d i f f i c u l t i e s were explored. In some cases, notably the be l i e f that "cold" i s an entity d i s t i n c t from and equivalent to "heat," the al t e r n a t i v e b e l i e f was apparently not i d e n t i f i e d by the teacher or by the textbook authors. Some alternative b e l i e f s were addressed in cla s s , but the discussion did not adequately c l a r i f y the concepts for some students. On one pa r t i c u l a r occasion (the discussion of the phase change investigation), the teacher was not at her best, and many students never did resolve the d i f f i c u l t ideas developed in that investigation. 161 The role of the teacher was c r i t i c a l in resolving alternative b e l i e f s . While th i s chapter has concentrated on the students and on learning, the next chapter w i l l examine the instruction provided during the unit. The focus w i l l be on the teacher and how she planned and implemented instruction in t h i s unit of the grade nine science program. 162 CHAPTER VI SCHOOL SCIENCE: INSTRUCTION 6.0. Introduction The ov e r a l l aim of t h i s study has been to investigate the interaction between students' prior b e l i e f s and in s t r u c t i o n . The previous chapter showed that although many students learned much about heat and temperature, there were s t i l l several alternative b e l i e f s held by students at the end of the unit. This chapter w i l l focus on the instruction provided by the teacher as she guided her students through the unit and suggest some tentative explanations as to why instruction did not always successfully resolve those alt e r n a t i v e b e l i e f s . A variety of i n s t r u c t i o n a l a c t i v i t i e s are' used in science classes. In this class, as in most junior secondary classes, the students were a c t i v e l y involved in learning. This active learning emphasized the acq u i s i t i o n of knowledge through the use of student investigations and class discussion, in contrast to lectures presented by the teacher. The various i n s t r u c t i o n a l a c t i v i t i e s that occurred w i l l be examined in terms of the roles played by the teacher in that p a r t i c u l a r a c t i v i t y or instance. One c r i t i c a l role f u l f i l l e d by a teacher i s that of managing, planning and implementing in s t r u c t i o n . The teacher must select d a i l y a c t i v i t i e s for the students. That selection i s influenced by the constraints of the curriculum, the textbook, the teacher's own values, interests and expertise, the 163 background and a b i l i t y of the students, and the available time and equipment. The teacher may choose to supplement or replace portions of the prescribed textbook, either to enrich, simplify or abbreviate i n s t r u c t i o n . The pressure of time i s always a l i m i t i n g factor, and frequently influences how a teacher chooses to present a p a r t i c u l a r topic or idea to the c l a s s . Time, as was evident in the present study, may become es p e c i a l l y c r i t i c a l as the end of term approaches. One of the major i n s t r u c t i o n a l formats in many science classes is class discussion. Ideally, discussion should involve the students and teacher exchanging ideas in such a way that the students' thinking i s steered l o g i c a l l y and systematically toward a s c i e n t i f i c a l l y acceptable understanding of the phenomenon being considered. A l l students should be equally involved in the dialogue. In practice, t h i s l a t t e r ideal i s a l l but impossible to a t t a i n . Some students are anxious to answer every question, while others are very reluctant to say anything and when required to respond, do so as b r i e f l y as possible. For less complex science topics, the ideal of a l l students understanding the topic of discussion may be achieved quite re a d i l y . For example, the students in this class were a l l able to read a thermometer and to define temperature as "hotness or coldness" with confidence at the end of the unit. For the more complex topics, however, understanding was achieved by only a few students. Although the teacher did provide opportunities for students to do investigations and the results of those investigations were discussed in cl a s s , many students did not achieve the desired understanding of heat and temperature 164 concepts. This chapter w i l l f i r s t examine how the teacher organized the unit and her approach to i n s t r u c t i o n . Class discussion w i l l be p a r t i c u l a r y emphasized. Instructional and school science factors which may have been related to the persistance of alt e r n a t i v e b e l i e f s w i l l then be i d e n t i f i e d and examined. 6.1. Analysis of the Data Instruction w i l l be examined in terms of the " r o l e " played by the teacher at any p a r t i c u l a r time. Two aspects of instruction were explored—how instruction was organized and, in p a r t i c u l a r , how the teacher and students interacted in class discussion. F i r s t , the teacher's role as " i n s t r u c t i o n a l manager" w i l l be considered. This role involved the planning and implementation of the d a i l y a c t i v i t i e s . Two types of large group teaching situations were also i d e n t i f i e d : discussion and information. The major large group a c t i v i t y consisted of discussion or "dialogue" between the teacher and the students about the topics being studied. Discussion was used to introduce new topics, take up assigned questions, discuss various aspects of the investigations (purposes, results and/or conclusions), and review various concepts students were expected to understand. Three d i f f e r e n t i n s t r u c t i o n a l roles were i d e n t i f i e d during class discussions. These were: the teacher as "evaluator" of student responses; the teacher as "provider" or interpreter of s c i e n t i f i c knowledge; and the teacher as "mediator" of discrepancies in student knowledge, ideas and b e l i e f s . The second type of large group 1 65 a c t i v i t y might be described as "directions." This consisted of the teacher providing information or instructions about various a c t i v i t i e s or procedures to be followed. Examples included assigning homework, informing students as to when and where to hand in laboratory reports and other assignments, elaborating on or supplementing instructions for conducting investigations, other management instructions, etc. This teacher was not observed to give formal, structured lectures to the c l a s s . However, she did occasionally spend several uninterrupted minutes elaborating on some of the more d i f f i c u l t concepts for students who were having d i f f i c u l t i e s . For purposes of t h i s study, directions were not considered to be important in terms of the overall learning climate provided by the teacher, and hence were not subjected to further scrutiny. The methods of c o l l e c t i n g and categorizing the data on class dialogue have been described e a r l i e r . The analysis in t h i s chapter w i l l examine the teacher's responses to student answers and w i l l investigate the roles of the teacher during that dialogue. When a student responded to a question, t y p i c a l l y the teacher f i r s t evaluated the response, then either continued discussing the question, or went on to another question. Four teacher response categories represented evaluation responses: acknowledge answer, wrong answer, redirect, and ignore/dismiss. If the teacher was not s a t i s f i e d with a student's response, she either attempted to e l i c i t more information from the student (encourage/explore), redirected the question to another student ( r e d i r e c t ) , or provided the desired response herself. The 166 l a t t e r included the stating of factual knowledge or information (provide information), providing an explanation aimed at f a c i l i t a t i n g understanding of more complex ideas (explanation), or conducting a demonstration of a phenomenon (demonstration). When trying to e l i c i t more information from the students, the teacher used probes and further questioning aimed at helping the student work out the desired answer her/himself. In thi s chapter, the teacher's responses w i l l be examined in terms of the i n s t r u c t i o n a l roles described above. 6.2. The Teacher as Instructional Manager A teacher is responsible for organizing units and lessons so as to f a c i l i t a t e student learning. She or he must decide how the prescribed curriculum w i l l be implemented. That decision may be influenced by the teacher's background and preferences, as well as by the interests and a b i l i t i e s of the students. Some of the prescribed topics, such as heat and temperature, are very d i f f i c u l t for many students. For such topics, i t i s inevitable that there w i l l be c o n f l i c t s between the needs of the lower a b i l i t y students and those of the more able students. The teacher must s t r i k e a fine balance, so as to avoid losing the weaker students who do not understand the p r i n c i p l e s involved, yet at the same time maintaining interest and challenging the more able ' students. A teacher may spend proportionally more than the recommended time on topics studied early in the school year, then f i n d the end of term approaching with l i t t l e time to complete the remaining topics. This was the case for thi s c l a s s . The heat and temperature unit was not started u n t i l the 1 67 end of May and another unit remained to be taught. Thus, the i n t e l l e c t u a l demands of the content and the pressure of time served as major constraints influencing the instruction that was provided. The remainder of thi s section w i l l present some of the teacher's views as to the more important aspects of the heat and temperature unit and on the d i f f i c u l t y of the topic. A description of the f i r s t lesson w i l l be provided to i l l u s t r a t e her approach to organizing and teaching the unit. The a c t i v i t i e s and assignments of the remaining lessons w i l l be summarized. The teacher had taught for several years, but had only taught the heat unit once before. Her f i e l d of s p e c i a l i z a t i o n was biology. When asked what she considered the most important parts of chapters seven to ten, she replied:-That's a good question. When, you apply i t to their everyday l i v e s , which is b a s i c a l l y what I consider most important, temperature's important, umm, expansion's important, and so are conduction, radiation, conduction [ s i c ] , because they're a l l a part of their l i v e s . And the part I didn't cover [chapter 10] i s also r e a l l y , r e a l l y important because of the energy c r i s i s . The less important concepts were i d e n t i f i e d as: I don't think the greenhouse ef f e c t i s a l l that important. It's i n t e r e s t i n g . They do have i t as part of their l i v e s — in cars and s t u f f . The teacher f e l t that the heat and temperature unit was among the more d i f f i c u l t units in the grade nine course. Within the unit, d i f f e r e n t i a t i n g between heat and temperature was the most d i f f i c u l t concept to teach. She f e l t that by the end of the unit the student should be able to define temperature as "the hotness or coldness of something," and heat as "the 1 68 addition of mechanical energy to the p a r t i c l e s . " The teacher was then asked how she would explain the difference between heat and temperature to an adult who knew l i t t l e about science. She re p l i e d : It would have to be n o n - s c i e n t i f i c , umm, I guess I would say that temperature would be the gradient they can feel with their senses, p a r t i c u l a r l y the sense of touch. Uhh, and i t can be measured by a thermometer, which they're a l l accustomed to. When you get down to measuring heat energy, that's more t h e o r e t i c a l . Uhh, [5 sec. pause] i t would have to be compared with some motion—I'm just trying to think of something—the motion which accumulated gives you an end product. Uhh, perhaps the motion of several engines p u l l i n g together—the difference between a four power and a six power engine. So that there's the idea of several things added together to give a work—an energy—a t o t a l energy and, i t ' d have to be something along that l i n e -something in their everyday l i v e s . The teacher followed the textbook rather c l o s e l y , omitting the optional sections. Most of the required sections were assigned as reading and were discussed in c l a s s . Investigations were either performed by a l l students or as demonstrations by the teacher or by a small group of students. The topics presented in chapter nine (Heat Transfer) were discussed in cla s s , but the students were not asked to read any sections of that chapter. In the f i r s t lesson, the topics covered by the f i r s t and t h i r d sections of chapter seven, "Heat energy and energy transformations" (Sec. 1.34) and "The energy of p a r t i c l e s " (Sec. 1.36) were discussed. It was pointed out that heat energy i s involved in a l l energy transformations and the students were asked to give examples of energy transformations involving a variety of .different forms of energy. Time was provided for the students to answer the question on energy 1 69 transformations from the text, and the answers were then discussed. The teacher then set some lead shot r o l l i n g on the overhead projector to simulate the motion of the p a r t i c l e s of matter, while introducing the discussion on the energy of p a r t i c l e s . The discussion dealt with the idea that no mechanical energy i s lost because of c o l l i s i o n s among the p a r t i c l e s of matter. Some of the students were d i s s a t i s f i e d with t h i s idea, but the teacher f i n a l l y cut off the discussion by r e f e r r i n g the class to diagrams in the textbook and by involving some di f f e r e n t students in the discussion. The students were then asked to read o r a l l y the section on the energy of p a r t i c l e s and questions were assigned. The teacher also t o l d the students to "read and prepare" the next two sections, both of which were investigations, ("Measuring temperature with a mercury thermometer" and "Measuring temperature by expanding s o l i d s " ) . The teacher reminded the students of what she meant by "prepare" as follows: Teacher: ...when I say prepare, what I mean, i t might be a good idea to jot this down somewhere. It's a long time since you've done t h i s . I want you to read over the lab. [pause] Then, write the t i t l e , write down purpose. How do you know what the purpose is? Carolyn? Carolyn: The question to be i d e n t i f i e d . Teacher: Good. And, then in a few, and I mean l i k e two or three (keep this r e a l l y , r e a l l y short) sentences state the method. So, for instance, the method could be something l i k e , we heated some bimetallic s t r i p s and watched what happened. Male student: What experiment i s this? Teacher: Something r e a l l y short, and then four, draw any charts that you're going to need so you're a l l ready to start the lab. As she was speaking, the teacher wrote the following on the 170 overhead projector: 1. write the t i t l e 2. write the purpose 3. in a few (2 or 3) sentences state the method 4. draw any charts needed for observations. The students were given the last few minutes of the period to begin working on the assignments. Thus, on Day 1 the students were introduced to the topics heat and temperature and necessary background information on energy and p a r t i c l e s was reviewed, drawing on the students' previous knowledge and experience where possible. The teacher did not attempt to e l i c i t the students' prior b e l i e f s about any of the topics discussed. The assignment included questions on the ideas discussed that day, as well as preparation for the two investigations to be performed the next period. A summary of the d a i l y class a c t i v i t i e s and of the assignments was recorded by the investigator (Table 6.1). Ten class periods were devoted to. chapters seven to nine. As noted in the teacher's comments above, chapter ten was omitted due to lack of time (the end of term was two weeks away and the biology unit had not yet been taught). As time became more pressing, the teacher provided alternative readings to the textbook sections on conduction and convection. The alternate readings were more concise and factual than the equivalent textbook sections. No readings were assigned on radiation. A l l students performed b r i e f investigations two periods, and during a t h i r d period one group of students performed a demonstration investigation. The teacher performed demonstrations two periods. The teacher and selected students also performed demonstrations to i l l u s t r a t e conduction and convection. The 171 Table 6.1 Class A c t i v i t i e s and Assignments Day 1: Discuss energy transformations involving heat energy. Sec. 1.34 (Heat Energy and Energy Transformations); do quest ion 1. Read 1.36 (The Energy of P a r t i c l e s ) ; do questions 1, 2. Assignment: Read and prepare 1.37 and 1.38 for next day. Day 2: Do Inv. 1.37 (Measuring Temperature with a Mercury Thermometer); discuss conclusion. Assignment: questions 1-4, Inv. 1.37. Inv. 1.38 (Measuring Temperature by Expanding Solids) demonstration and discussion. Assignment: questions 1-5. Day 3: Inv. 1.38: discuss conclusion. Read 1.40 (Thermometers). Assignment: Sec. 1.41 (Review): do questions 1-6. Day 4: Read and do Inv. 1.42 (The Heat Energy and Temperature of Different Objects, Parts I and I I ) . Day 5: Discuss questions, Sec. 1.41. Discuss d i s t i n c t i o n between mechanical and heat energy and the p a r t i c l e model. Discuss Inv. 1.42. Assignment: Inv. 1.42: questions 1-5, 7, 10; Read 1.43 (Heat Energy and Temperature), do questions 1-4. Day 6: Inv. 1.45 (Heat Energy and Temperature in Phase Changes) demonstration by 3 students; begin discussion. Assignment: do graph, questions 1-5, 7, 9, 10, conclusion. Day 7: Discuss conclusion and questions, Inv. 1.45. Conduction demonstration and discussion. Read hand-out on conduction; do questions 1-4 from Sec. 1.48 (Conduction). Day 8: Discuss conduction, insulation, questions 1-4. Convection demonstration and discussion. Complete review sheet, Chapter 8. Assignment: Read hand-out on convection; do questions 1-4, 7, 8 from Sec. 1.49 (Convection). Complete review sheet, Chapter 9. Day 9: Review and discussion—conduction, convection and radiation. Day 10: Unit test (prepared by teacher) and Posttest. 172 l a s t day was devoted to the teacher-made unit test and the investigator's posttest. Overall, the teacher reduced the time a l l o t t e d to the unit . from the 1 3 hours recommended in the teachers' guide to nine hours (plus one hour of t e s t i n g ) . 6 . 3 . The Roles of the Teacher During Class Discussion Most of the large group instruction consisted of class discussion or dialogue. The teacher posed questions, the students answered the questions and the teacher responded to the students' answers. The teacher had to evaluate the accuracy of the student answer and decide whether to go on to another question or to seek additional responses. If the student response was incorrect or incomplete, she either encouraged the responding student to continue, redirected the question to another student or provided the desired information herself. The discussion format was used to introduce new topics, discuss the results of investigations, take up assignments and for review. Discussions which introduced new topics were often accompanied by demonstrations of the phenomena. This section w i l l examine class dialogue to ident i f y how the teacher dealt with a variety of situations in which b e l i e f s were expressed that were inconsistent with school science. This w i l l be done by examining the roles played by the teacher during the discussions. The following roles were i d e n t i f i e d : 1. the teacher as an evaluator of the correctness of student knowledge, ideas and b e l i e f s , 2. the teacher as a provider or interpreter of science knowledge, and 1 73 3. the teacher as a mediator of discrepancies between students' knowledge, ideas and b e l i e f s ( i . e . , children's science) and school science or s c i e n t i s t s ' science. Within the l a t t e r role, the responses of the teacher were examined to determine the extent to which any of the following may have influenced her response: 1. the approach taken by the student who was questioning the teacher's statements, 2. the confidence the teacher had in her knowledge, 3. the ide n t i t y of the student involved. Each of these three roles w i l l be discussed in some d e t a i l in the sections that follow. 6.3.1. The Teacher as Evaluator of Student Knowledge, Ideas, and  Be l i e f s Each response from the teacher was based on an evaluation of the student's answer, whether or not an e x p l i c i t evaluative statement was made. Occasionally the teacher was uncertain as to what the student was thinking and would ask for a further explanation of the answer. The following excerpt provides an i l l u s t r a t i o n of thi s type of response. (Underlined segments were categorized as evaluative responses.) Teacher: Can you think of another property of matter that can change? Alan: The form. Teacher: The form. That's important. It's not one we've r e a l l y looked at yet. We're going to look at i t more today. The form or shape of matter might change. Can you explain what you mean by that, Alan? Alan: If i t ' s a gas or a s o l i d . Teacher: Or? 1 74 Alan: That's a l l . That's about i t . Teacher: If you have an ice cube, what form i s that? Alan: S o l i d . Teacher: Yes - and i f you warm i t up? Alan: Liquid. Teacher: Yes. We c a l l i t a change of? [pause] Does anyone remember the word for that? Melanie: Phase. Teacher: A phase change. An ice cube melts. That's good. That's one [property] I hadn't thought of. Any other ones? Here the teacher's i n i t i a l response to Alan was based on an incorrect assumption that he meant "shape" when he said "form." However, she was s u f f i c i e n t l y uncertain to probe and determined that in fact he was thinking of the phases of matter. The teacher was then able to e l i c i t the correct term from another student. Four of the six teacher responses began with an accepting evaluative statement. One response ("Or?") indicated to Alan that his answer was incomplete, without s p e c i f i c a l l y c a l l i n g i t such. Throughout the unit, there were only 13 occasions when the teacher s p e c i f i c a l l y t o l d a student that an answer was not correct (only two such responses were to g i r l s ) . The investigator judged 85 student responses to be either an alternative b e l i e f or an answer which was either incorrect or p a r t i a l l y correct (Table 6.2). This finding i s of interest in view of Sadker and Sadker's (1985) findings. In two-thirds of the 100 classrooms investigated, teachers were never observed to indicate to a student that his/her answer was incorrect. In the remaining classrooms, such responses accounted for five percent of the teacher/student interactions. The authors expressed 175 concern that students were not given adequate feedback when their answers were incorrect. Table 6.2 Student-Teacher Dialogue Number Percent Student responses to teacher questions: Correct 186 68. 6% Other (alternative b e l i e f s , p a r t i a l l y correct, incorrect, no response) 85 31 . 4 Total 271 1 00. 0% Teacher responses to students (excluding managerial and repeats): Providing/interpreting knowledge (information, explanation, demonstration) 1 1 4 26. 3 Evaluating: acknowledge/accept answer (109) negatively [wrong answer (13), redirect (81), ignore/dismiss (18)] 1 48 34. 2 Mediating discrepancies 171 39. 5 (encourage/explore) Total 433 100. 0% In the previous chapter, i t was noted that during the discussion of the phase change investigation the students were l e f t with two dilemmas. During the discussion the teacher was incorrect about two important ideas. (Before class that day the teacher had told the investigator she was not feeling well and had not slept well the night before. This undoubtedly affected 176 her teaching that day.) One of her mistakes concerned the temperature plateau. Theoretically, the temperature of ice water remains at 0°C u n t i l the ice completely melts. It has been seen that the temperature did slowly increase while the ice was melting, and that the teachers' guide indicated that this would occur as heating was too rapid for a state of equilibrium to be established while the ice was melting. The teacher expected there would be no increase in the temperature during melting, and without looking at the data, assumed th i s had indeed been the finding. During the discussion the teacher would not l i s t e n to Brian, who t r i e d to t e l l her that the temperature did increase during melting. The teacher was confident of her knowledge, and she was unwilling to abandon her posi t i o n . Other examples of the teacher erring in her evaluation of a student response have also been presented in the previous chapter. For example, she occasionally misled an incorrect response given by a student she considered to be very bright. At such times, i t appeared that she was not paying close attention to the response and assumed that that student would give the correct answer. When such errors were not i d e n t i f i e d and corrected, they did lead to problems for many students. 6.3.2. The Teacher as Provider or Interpreter of Science Knowledge The teacher, the textbook and the results of investigations provided the sources of s c i e n t i f i c knowledge for the students. The results of the dialogue analysis revealed that during class discussions approximately 25 percent of the teacher responses 177 were categorized as information, explanation or demonstration. Approximately 40 percent of her responses were categorized as encouraging students to work out answers or ideas for themselves (Table 6.2). The teacher tended to provide or interpret knowledge only when there was a s p e c i f i c reason for not probing or encouraging further responses from the students. Three d i f f e r e n t kinds of situations were observed: 1. Assignments were being taken up and the emphasis was on identifying the correct or appropriate answers. For example, Gordon was at the chalkboard drawing a diagram to show how a i r c i r c u l a t e s in a hot a i r home heating system. Gordon: Now, when you have your heat here and you're passing through the a i r in t h i s d i r e c t i o n , i t [the a i r ] comes in and right there i t w i l l pick up the heat molecules Teacher: [interrupting] Heat energy's being transferred. Gordon: transferred right there, and i t keeps carrying on the heat, and i t ' s forced up here and out into the a i r , where we feel i t . The teacher interrupted Gordon to provide the correct terminology, but she did not explore his underlying b e l i e f . In situations such as t h i s , where the teacher seemed to merely correct a term, the student may have interpreted her simple correction as an implied acceptance of the b e l i e f behind the term used by the student. If she had questioned Gordon about what he meant by "heat molecules," i t may have been more obvious to Gordon and others that there is no such thing as a "heat molecule." On t h i s occasion, the teacher seemed to be primarily concerned with providing the correct answer to the question, and she did not appear to recognize the implications of Gordon's 1 78 b e l i e f . 2. Discussion of a topic had continued for some time and the teacher was unable to e l i c i t the desired response from the students. For example, while discussing the phase change experiment some students s t i l l did not understand that the greater temperature change in the l i q u i d phase.did not necessarily mean a greater increase in heat energy (although this was the rationale for the inve s t i g a t i o n ) . It appeared that the confusion was due, at least p a r t i a l l y , to the l a b e l l i n g of the two axes on the graph. The horizontal axis was la b e l l e d "time," and the v e r t i c a l axis "temperature." Neither the text nor the teacher c l e a r l y pointed out that i t was the time measure which was d i r e c t l y related to the amount of heat energy, in contrast to the temperature axis. The following exchange occurred when a student was asked to respond to a question in the textbook. The question asked which required more heat energy—melting, r a i s i n g the temperature to the b o i l i n g point, or evaporating the water? Lynne: Raising the temperature. Teacher: 0. K. Would that take more heat energy than evaporating the water? Lynne: Well, we don't know... The teacher than asked Lynne a series of questions developing the ideas that as ice melts and as water gets hotter and f i n a l l y evaporates, the mechanical energy of the p a r t i c l e s increases and therefore the heat energy increases. Lynne readily accepted these propositions. Then, 1 79 Teacher: The more mechanical energy, the more heat energy. So which one is going to have the most heat energy? Lynne: The evaporated. Teacher: Yes. Another student: .When i t ' s [the temperature?] on the chart [ i . e . , the graph] there, i t ' s higher. Teacher: Mhm. That's what we would have seen. Once you get pure water to a 100°, i t ' s going to become b o i l i n g . Lynne: Then wouldn't i t be more heat energy to get i t to 100°? Teacher: No. The p a r t i c l e s have more heat energy [sic] when they reach evaporation stage. Although Lynne understood the idea that as water i s heated, i t s p a r t i c l e s gain mechanical energy and that the water gains heat energy, she did not relate that idea to the actual data and graph. Lynne s t i l l did not understand why there was more heat energy when the water was b o i l i n g , than when i t was being heated to the b o i l i n g point. That i s , in terms of the conceptual change model, the idea was i n t e l l i g i b l e to her, but i t was not plausib l e . At that point, the teacher provided the information that there i s more heat energy when the water i s evaporating, and thereby closed the discussion. She then went on to a di f f e r e n t question. 3. A student asked a s p e c i f i c question and i t was answered by the teacher. For example, during discussion of another phase change question i t was determined that 50g of steam at 100°C has more heat energy than 50g of l i q u i d water at 100°C. One of the boys asked: 180 Walter: Would that be because there's less p a r t i c l e s [ i . e . , in the steam] and there's the same amount of heat energy applied? Teacher: As? Walter: As water. Teacher: No. There's more heat energy in water vapour than there i s in just water. Walter: The reason why i t has more is because there's less p a r t i c l e s , but there's more heat energy. Teacher: You're contradicting yourself. Walter: Each p a r t i c l e i s getting more... Teacher: [interrupting] You're contradicting yourself. If you have 50g you have exactly the same amount of p a r t i c l e s , you should have, because... Walter: [interrupting] 50g of water vapour. Teacher: 50g [of water vapour] would have a bigger space i s a l l , and 50g of water would be smaller, but you'd s t i l l , have the same number of p a r t i c l e s . In t h i s example, the teacher responded to Walter (a student she considered to be very bright) with a factual response. She did not attempt to encourage him to work out the idea himself (as she had done with Lynne in the previous example) or check to see i f he understood her response. He did not, but he persisted with his questioning. The teacher continued to answer his questions. In t h i s instance, Walter's alternative b e l i e f was resolved due to his persistence in questioning the teacher. 6.3.3. The Teacher as Mediator of Discrepancies Between School Science and Children's Science We have seen that the most frequent response category for teacher responses to student answers was encourage/explore. In a li m i t e d number of situations the teacher responded by providing a statement of facts, but this did not occur 181 frequently. Most often the teacher t r i e d to encourage the student to rethink or to elaborate on her or his answer—that i s , the teacher acted as a mediator, s t r i v i n g to help the student reconcile the differences between his or her be l i e f (children's science) and the desired view (school science). Again, these findings were remarkably similar to those reported by Sadker and Sadker (1985). Their equivalent category, "remediation," was observed in 99 percent of the the classrooms, and accounted for one-third of a l l classroom interactions. By comparison, in this study "encourage/explore" accounted for 35.6 percent of teacher responses. As mentioned e a r l i e r , a teacher i s t r u l y faced with a number of dilemmas with respect to guiding students who do not understand the ideas being presented. The f i r s t dilemma is to ide n t i f y the students who are having d i f f i c u l t i e s . It i s usually the more able students who w i l l ris-k asking for help when they do not understand something. These are the students who expect science to make sense and who believe they are capable of achieving understanding. As i l l u s t r a t e d by the example of Walter above, brighter students frequently asked for explanations when they did not understand something. They expect to experience meaningful learning. On the other hand, students who have d i f f i c u l t i e s with science may not expect i t to make sense. Presumably, their past experience with school science has led them to believe that i t i s not comprehensible. Their approach to learning science is to memorize d e f i n i t i o n s and other facts, so they can be repeated on the te s t . They are s a t i s f i e d with rote learning. Cathy and Susan provide examples 182 of such students. During the pretest interview when Cathy was asked to give reasons for her answers, she almost always rep l i e d either that she did not know or she had guessed. Most of Cathy's written assignments were, word-for-word, i d e n t i c a l to Jane's. When Susan was interviewed, she was somewhat more responsive than Cathy had been. Rather than a simple, "I dunno," Susan would reply, "I don't know. (laugh) I don't r e a l l y know much about science," or "I don't know. I can't think of anything." Susan's written work was occasionally i d e n t i c a l to that of her more able partner, Carolyn, but not always. Her answers to questions were often placed in quotation marks and were i d e n t i c a l to passages in the textbook. Like most of the students in the cl a s s , neither Cathy nor Susan was ever observed to ask the teacher to explain something she did not understand. However, Susan did occasionally approach the teacher to ask for the correct answer to a p a r t i c u l a r question (a fine, but important d i s t i n c t i o n ) . Cathy always consulted Jane, not the teacher, when she had questions. In so doing, she did not r i s k being encouraged to find the answer for herself, thereby exposing her lack of understanding. When students are unwilling to ask the teacher for assistance, t h e i r lack of understanding i s d i f f i c u l t to i d e n t i f y . It w i l l not l i k e l y be detected unless the student i s c a l l e d upon in class and is not able to respond appropriately. This undoubtedly results in many d i f f i c u l t i e s not being i d e n t i f i e d by the teacher, except when assignments are handed in or tests are graded. In the case of assignments, as we have noted, .students frequently worked together and the answers were often provided by those most able. 1 8 3 By testing time, instruction has been completed, and many students are no longer interested in the correct answers. In most cases, the students gave acceptable answers to questions posed by the teacher. Approximately one-third of the student responses were judged by the investigator to be other than correct. It has been noted that the most frequent category of teacher response to student answers was encourage or explore. Three possible types of teacher response to incorrect or incomplete answers have also been i d e n t i f i e d . Each of these types of response has both advantages and disadvantages. The stated goals of school science do not include memorizing u n i n t e l l i g i b l e d e f i n i t i o n s or facts. Rather, i t is desirable to encourage students to develop an understanding of the concept ( i . e . , for the student to experience meaningful learning). An example to i l l u s t r a t e the teacher providing an encouraging response i s presented below: Teacher: Those are the three things you needed to consider in your conclusion [to the phase change inve s t i g a t i o n ] . F i r s t of a l l , l e t ' s go back and review what we mean by heat energy. What ij; heat energy? Jane: The t o t a l sum of a l l the mechanical energy of the part i c l e s . Teacher: How could we go about measuring heat energy? Do we measure i t d i r e c t l y ? Joe? Joe: Umm, use a thermometer and dump i t in the water. Teacher:' O.K. So what are we measuring when we use a thermometer? Joe: Umm, the temperature. Teacher: Which is? Joe: Which i s , umm, how hot i t i s . Teacher: Hotness and coldness is-measured by temperature, so we're not measuring heat energy d i r e c t l y . We can't measure 1 84 those l i t t l e p a r t i c l e s moving around and sum up the mechanical energy to give us heat energy d i r e c t l y in the classroom. So, we measure i t i n d i r e c t l y by measuring the temperature, hotness or coldness. Now, turn to your graphs. [20 second pause while students take out their graphs] O.K. What i s the f i r s t thing, or one of the things you can say when you look at your graph? What do you notice about the heat energy? [2 second pause] Can you t e l l anything about heat energy from the graph? Alan: It's absorbed by the water. Teacher: O.K. [turning to another student] Do you want to share that with us? [br i e f , u n i n t e l l i g i b l e exchange between the teacher and a student who was tal k i n g to another student and not attending to the class discussion] O.K. Alan said, would you say i t loudly so the whole class can hear i t ? Alan: Water absorbs heat energy. Teacher: Where i s the heat energy coming from? Alan: The burner. Teacher: So one of the things that Alan said i s that there's usually a transfer.. He c a l l e d i t "absorbing." Is there anything else you can t e l l us looking at the graph? [4 second pause] Melanie: After the ice melted the temperature increased very ste a d i l y . Teacher: There are two very important things there. She said after the ice melted, i s one very important thing and we'll come back to that. The temperature increased very steadily, which i s the second thing she said. What can we say about the heat energy of the p a r t i c l e s [ s i c ] in the water? After the ice melted? Cindy: Umm, they're getting more and more heat energy. Teacher: Mhm. And the mechanical energy of the p a r t i c l e s i s increasing, too. O.K. Now, l e t ' s go back to the f i r s t thing she said. It's very important. "After the ice melted." What happened before the ice melted? Was heat energy being transferred? Brian and another student: Yes. Teacher: How do you know? Brian: It started to melt. [And the discussion continued] In t h i s introductory segment of the phase change 185 discussion, Jane f i r s t provided the textbook d e f i n i t i o n of heat energy. The teacher then turned to Joe to ask how heat energy could be measured. I n i t i a l l y Joe said that the thermometer measured heat energy. The teacher used probing questions to c l a r i f y that i t was temperature, not heat energy, that was measured by the thermometer. She then told the class that they could not measure heat energy d i r e c t l y and had them look at their graphs to determine what the graphs showed about heat energy. Alan's response that heat energy is absorbed by the water was addressed and the teacher provided the term "transferred" as being equivalent to "absorbed." The teacher did not probe to ensure that the concept which Alan c a l l e d "absorbing" was indeed equivalent to "transfer." The teacher then asked for further ideas from the students. Melanie's response allowed the teacher to address the idea that the teacher had wanted to deal with, that the 'rate of temperature increase changed after the ice had melted. The teacher emphasized what Melanie had said and then probed further to determine what was happening to the p a r t i c l e s as the temperature increased. If the teacher encourages a student to think out a problem in class, other students may benefit by the discussion. The disadvantages of this approach include the time required, during which some students in the class may become bored and r e s t l e s s , and the p o s s i b i l i t y that the student may be embarassed i f she or he i s unable to give the desired response. Consequently, this type of probing exchange with a student is sometimes more appropriate in a one-to-one s i t u a t i o n , rather than in the large 186 group. A l t e r n a t i v e l y , the teacher or another student may provide the "correct" answer for a l l students, making more e f f i c i e n t use of class time -for the large group. Sometimes when an i n i t i a l response was inappropriate the teacher simply redirected the question to another student. For example: Teacher: Now, f i r s t of a l l , as you measure the temperature i t would be wise to write down what you mean by temperature. What does temperature mean to you? When you c a l l i t measuring temperature, what are you measuring? Male student: How hot i t i s . Another male student: The heat that's contained in the object. Teacher: A l l right. The heat that's contained within the object. Brian? Do you have another way of putting i t ? Brian: How hot something or how cold something i s . Teacher: Yes. That's probably the easiest, way to write i t down. Female student: How hot or cold something i s . Teacher: So temperature, and you should copy t h i s down as I write [on the overhead], i s the hotness or coldness of an object. On other occasions the teacher provided the desired answer her s e l f . Examples of thi s have already been presented (Sec. 6.3.2). Another example occurred during the discussion of an assigned question. The teacher f i r s t directed a probe to another student, and then provided additional information he r s e l f . Melanie: [reading her answer] If two objects have the same mass and the same temperature, but one is made of water and the other i s made of lead, then the one made of lead has more heat energy. [3 second pause] 187 Male student: Mhm. Teacher: A c t u a l l y , no. S e v e r a l students: Nooo? [S e v e r a l speaking a l l at o n c e — o n e male v o i c e heard c l e a r l y ] : That's denser, so i t should be. Teacher: What's the problem with using d e n s i t y ? [ S e v e r a l students speaking a l l at o n c e - - u n i n t e l l i g i b l e ] Teacher: Who can e x p l a i n t h a t ? Jane: You have the same mass of each of them, so 50g of l e a d and 50g of water, and the water i s going to have more heat energy because the p a r t i c l e s are moving f a s t e r and so they have more mechanical energy. Teacher: Mhm. Remember you can't change the mass of the t h i n g but you can change the way the p a r t i c l e s are moving i n the water. The water i s going to be moving f a s t e r . The whole t h i n g i s going to have more heat energy. The p a r t i c l e s themselves w i l l have more mechanical energy. Female student: Does that mean they take up the same area? Teacher: No. I t j u s t means they have the same--you have 50g of each. Female student: But 50g Teacher: [ i n t e r r u p t i n g ] The volume might be d i f f e r e n t . In t h i s segment (which has been quoted e a r l i e r ) Jane was asked to e x p l a i n a d i f f i c u l t concept. The teacher b r i e f l y e l a b o r a t e d on Jane's response. One g i r l asked a q u e s t i o n which r e v e a l e d that she d i d not understand the e x p l a n a t i o n , but r a t h e r than e x p l o r e the student's d i f f i c u l t y the teacher p r o v i d e d a minimal response to the q u e s t i o n and was u n w i l l i n g to d i s c u s s i t f u r t h e r . U n f o r t u n a t e l y , when the c o r r e c t answer i s merely p r o v i d e d and not e x p l a i n e d , those students who d i d not understand the concept are not helped to come to any understanding of the ideas i n v o l v e d . The p o s t t e s t r e v e a l e d that 188 many students continued to believe that denser matter had more heat energy than less dense matter. Sometimes i f a student gave an answer which was either incorrect or incomplete, or i f the student/s seemed unsure of the correctness of a response,- the teacher referred the question to the entire class to vote on the correct answer. An example of t h i s occurred when expanding p a r t i c l e s were being discussed. The teacher asked, "Do the p a r t i c l e s get bigger themselves?" A few students said, "Nooo." The teacher then asked, "How many say no?" [Several hands were raised.] "How many say yes?" [This time fewer hands were raised.] In t h i s situation the students were asked to commit themselves to a decision. The teacher then continued by addressing one pa r t i c u l a r student who had voted yes, and discussed his reasons for making that choice. 6,4. Instruction and Alternative B e l i e f s The previous sections have looked at the various types of resposes the teacher provided during clas discussion. In this section, the interactions which occurred when alternative b e l i e f s were expressed by students w i l l be examined. The conceptual change model of Posner et a l . (1982) has been presented in Chapter II. According to that model, when new phenomena are presented which are incompatible with the student's exi s t i n g framework, the new idea w i l l not l i k e l y replace the alternative b e l i e f unless several conditions are met. These conditions are: 1) the student must be d i s s a t i s f i e d with his/her existing concepts; 2) the student must be able to understand the concept well enough to explain i t ( i . e . , i t must 189 be i n t e l l i g i b l e ) ; 3 ) the new concept must resolve anomalies in the existing concept ( i . e . , i t must be p l a u s i b l e ) ; and, 4 ) the new concept must have predictive power and be preferable to the old concept ( i . e . , i t must be f r u i t f u l ) . Only when a student comes to believe an idea and then finds i t preferable to his/her prior b e l i e f , has i t become plausible and then f r u i t f u l . If students' alternative b e l i e f s are to be displaced, then they must be persuaded that the school science concept i s preferable to, and more useful than, the a l t e r n a t i v e b e l i e f . This did not appear to happen for many of the concepts being dealt with in t h i s unit. The idea of basing instruction on students' prior b e l i e f s is a r e l a t i v e l y new approach to science teaching. Only in very recent years have researchers been investigating t h i s approach, and with few exceptions, i t i s not in use in science classrooms. Some alternative b e l i e f s do become known to teachers as they provide i n s t r u c t i o n . A student may be told that his/her idea is incorrect for certain reasons, and that another idea is correct for certain other reasons. Some teachers may use experiments or demonstrations, or refer a student to an authority, such as an encyclopedia, in an attempt to d i s c r e d i t students' alternative b e l i e f s . Some common alt e r n a t i v e b e l i e f s have been i d e n t i f i e d by curriculum developers, and/or textbook and teachers' guide authors, and teachers are then al e r t e d that a p a r t i c u l a r concept presents d i f f i c u l t i e s for students. In such cases, alternative b e l i e f s may be i d e n t i f i e d , although the term i t s e l f i s not used. Moreover, few, i f any, teachers would choose to systematically e l i c i t students' b e l i e f s p r i o r to i n s t r u c t i o n , in order to f i r s t 1 90 i d e n t i f y their alternative b e l i e f s , and then a c t i v e l y discuss those alternative b e l i e f s during in s t r u c t i o n . This approach to instruction i s not yet a common feature in university programs which t r a i n students to become science teachers. There is l i t t l e motivation for most students to try to understand d i f f i c u l t concepts. Under the ex i s t i n g reward structure in most science classrooms, i t is correct answers, not understanding, that are rewarded. The target students described in t h i s study are t y p i c a l of those found in many science classrooms. Students l i k e Jane are rewarded for providing correct answers. Students l i k e Alan are less l i k e l y to be rewarded,' as they are seldom provided with the opportunity to demonstrate their understanding of science concepts. Students such as Brian present the school science view on tests, while retaining t h e i r alternative b e l i e f s . Many- students rely on memorizing correct answers to achieve a sa t i s f a c t o r y l e v e l of performance in school science. At best, school science measures of learning and/or knowledge determine which concepts are i n t e l l i g i b l e to the student. Even rote-learned responses may serve as acceptable answers on assignments or te s t s . In such cases, the concept need not even have.been i n t e l l i g i b l e to the student. Persistent alternative b e l i e f s have been i d e n t i f i e d from ten topic areas. This study has examined the persistent alternative b e l i e f s to id e n t i f y possible factors which may account for that persistence. The goal of the study has been to suggest some possible reasons for why students did not reject their a l t e r n a t i v e b e l i e f s in favour of the ideas presented in 191 school science. When the instruction provided for the ten topics was examined, one or more of f i v e types of situations appeared to be involved in most cases. In t h i s section, those situations w i l l be described and examples of each w i l l be presented. 6.4.1. School Science Attempts to Explain Heat Phenomena in Terms of Mechanical Energy Heat phenomena can be investigated at two l e v e l s : the macroscopic and the microscopic ( i . e . , p a r t i c l e ) l e v e l s . When thermodynamics i s studied in introductory physics courses, i t i s presented at the macroscopic l e v e l . P a r t i c l e s , atoms and molecules are not discussed. At the microscopic l e v e l , quantum theory i s required to account for . phenomena. Clearly, such explanations .are inappropriate for grade nine science, yet this school science program attempts to use microscopic explanations in terms that could be understood by grade nine students. -A number of problems occurred as students attempted to make sense of those explanations. One notable example was the attempt to explain why there i s no loss of mechanical energy due to the c o l l i s i o n s among p a r t i c l e s . The explanation provided in the teachers' guide (quoted e a r l i e r , in sec. 5.4.1) and presented by the teacher in class, was challenged by Brian and Joe, and has been termed "absolute nonsense" by one ph y s i c i s t (Matthews, Note 2). A l l of the phenomena that were explained or defined on the basis of mechanical energy and/or the transfer of mechanical energy among p a r t i c l e s were largely u n i n t e l l i g i b l e to the students. Some students r e l i e d on memorizing and were able to 1 92 reproduce the appropriate d e f i n i t i o n s and statements. Those who sought meaning in school science, notably Joe and Brian, were disturbed by such explanations. Alan was interested in finding explanations, but rather than seeming disturbed when an explanation was unsatisfactory, he laughed and appeared to forget about i t . Some school science ideas did not present p a r t i c u l a r problems for students, but were incorrect, according to s c i e n t i s t s ' science. These included the idea that mechanical energy i s solely dependent upon the speed of the p a r t i c l e s , and the idea that in conduction, heat energy (internal energy) i s transferred solely by c o l l i s i o n s among p a r t i c l e s . 6.4.2. The S c i e n t i s t s ' Science Explanation of a Phenomenon Was  Omitted There were instances where students made observations which 'were contrary to their expectations. As has been shown, di f f e r e n t students responded d i f f e r e n t l y to such situ a t i o n s . For example, Jane tended to reject observations which were contrary to her expectations. She appeared to be disturbed by such discrepancies, and wanted experimental results which would support her b e l i e f s . To the contrary, Alan and Joe seemed intrigued by such findings. They t r i e d to f i n d an explanation for their observations and were stimulated to explore further. When there was no opportunity to f i n d an explanation to account for their observations, Joe, in p a r t i c u l a r , was l e f t feeling frustrated. In such cases, school science t o l d the student that a p a r t i c u l a r alternative b e l i e f was not correct, yet did not provide an alternative explanation. Students who had made a 193 commitment to an alternative b e l i e f were therefore l e f t without any concrete reason for rejecting that alternative b e l i e f . One example where th i s appeared to be a factor was the persistence of, the idea that the density of an object is d i r e c t l y related to the amount of heat energy in the object. The students were not introduced to the concept of s p e c i f i c heat capacity (although there i s an optional section in the textbook dealing with s p e c i f i c heat). In their prior experiences in school science, the students had learned that density is an important c h a r a c t e r i s t i c property of matter. No other property had previously been studied in such d e t a i l . In this instance, not only did school science not provide the students with an alternative property which could account for the observed differences in heat energy, but the teacher t o l d the students she would not consider "density" to be a wrong answer. (She then added that i t was better to say type or kind of material.) It was also noted that the g i r l s tended to comply with t h i s request ( i . e . , to not use the term "density"), whereas the boys did not. Latent heat i s another complex concept which was not s p e c i f i c a l l y mentioned. Latent heat accounts for the temperature plateaus which occur during a change of phase, an observation which was not expected by the students, and which caused d i f f i c u l t y for many. In both the s p e c i f i c heat capacity and latent heat examples, students were asked to explain observations without having the "whole story" available to them. School science appears to assume that the student w i l l accept the word of the teacher and the textbook on such matters, and 1 94 indeed, many students do so. However, to expect students to provide explanations without evidence i s inconsistent with the s p i r i t of the junior secondary science program, as described in the curriculum guide. The observations of phenomena which s c i e n t i s t s c a l l " s p e c i f i c heat capacity" and "latent heat" were not questioned by weaker students, who appeared to consider science to be incomprehensible, somewhat l i k e magic. The more competent students, who did try to make sense of their observations, became frustrated as they attempted to understand the reasons for these unexpected findings. 6.4.3. Alternative B e l i e f s Were Not I d e n t i f i e d There were two .instances where i t appeared that not only was an alternative b e l i e f that caused d i f f i c u l t i e s for some students not i d e n t i f i e d by the teacher, but the teachers' guide had not'mentioned the p o s s i b i l i t y of that d i f f i c u l t y . - At the end of the unit, Jane and others had not abandoned the be l i e f that cold i s equivalent to, but d i f f e r e n t from heat. Neither the teachers' guide nor the curriculum guide had i d e n t i f i e d this as a potential d i f f i c u l t y for students. The idea had never been discussed in c l a s s . It has already been suggested that the school science d e f i n i t i o n of temperature as "the hotness or coldness of matter" may have served to validate t h i s alternative b e l i e f that hot and cold are equivalent and d i f f e r e n t e n t i t i e s . The use of t h i s d e f i n i t i o n appears to be an attempt to provide students with an i n t e l l i g i b l e a l t e r n a t i v e to defining temperature as the average mechanical energy of the p a r t i c l e s . Another d i f f i c u l t y which was not i d e n t i f i e d was the 195 l a b e l l i n g of the axes on the graph of the water temperature as i t was being heated in the phase change investigation (Inv. 1.45). Students were to label the axes "temperature" and "time," and the students assumed that the temperature axis represented heat. Again, t h i s alternative b e l i e f was not i d e n t i f i e d by the teacher, nor was i t anticipated in the teachers' guide. Students who held this b e l i e f were unable to understand the true relationship between heat and temperature in that investigation. These two alternative b e l i e f s could probably have been corrected r e l a t i v e l y e a s i l y , it^ they had been recognized by the teacher. Unless a teacher has implemented s p e c i f i c strategies for i d e n t i f y i n g students' prior b e l i e f s , a l t e r n a t i v e b e l i e f s such as these are not l i k e l y to be recognized. In the midst of a class discussion, a teacher must balance a number of p r i o r i t i e s . Quite understandably, p r i o r i t y i s often given to management and finding correct answers. 6.4.4. Confusion About the Use of S c i e n t i f i c Models School science often u t i l i z e s models and analogies to help students understand s c i e n t i f i c phenomena. Students' prior experience with models outside of school science i s often li m i t e d to concrete scale models of objects, such as cars, airplanes, etc. Such models are i d e n t i c a l in form with the object being modelled, but they d i f f e r in s i z e . Many students appeared to believe that s c i e n t i f i c models are necessarily i d e n t i c a l in form, but d i f f e r in size from the object they represent. That i s , the students seemed to think' of a "model" in a more r e s t r i c t e d sense than i s used by s c i e n t i s t s . For 196 example, the atom may be thought to be very much smaller, but otherwise i d e n t i c a l to the c l a s s i c a l Bohr model, with a s o l i d nucleus of protons and neutrons, and with electrons t r a v e l l i n g in o r b i t s , similar to the planets c i r c l i n g the sun. The use of the p a r t i c l e model, as we have seen, caused d i f f i c u l t i e s for many students. Some did not question the model, but neither did they understand i t s implications for the heat phenomena being investigated. Joe and Brian t r i e d to make sense of the p a r t i c l e model, and found i t inconsistent with their p r i o r knowledge about the structure of the atom. Rejecting t h i s model appeared to account for Brian not abandoning his b e l i e f that p a r t i c l e s could expand. Brian was certain that the " p a r t i c l e , " be i t atom or molecule, i s not the smallest known p a r t i c l e of matter, and hence he may have concluded that there was no reason why a p a r t i c l e should not be able to expand. The textbook had several diagrams which i l l u s t r a t e d p a r t i c l e motion. In those diagrams, the p a r t i c l e s were c i r c u l a r in shape. The scale of the distance between the p a r t i c l e s was approximately three times the diameter of the p a r t i c l e s . The students did not appear to have any understanding of the extent to which those diagrams reflected the actual nature of molecules or the scale of a molecule in comparison to the spaces between the molecules. In another example, the teacher used the analogy of lead shot r o l l i n g on the overhead projector to i l l u s t r a t e p a r t i c l e or molecular motion. This model was not help f u l for many of the students in this c l a s s . 197 6.4.5. The Teacher's Explanation Was Not Understood by the Students There were instances where the teachers' guide had i d e n t i f i e d p o t e n t i a l d i f f i c u l t i e s , and where the teacher herself recognized that the concept was d i f f i c u l t for students. On some such occasions, the teacher t r i e d to explain an idea and the students either did not understand or they did not accept the explanation. Some examples of t h i s , such as the expansion of p a r t i c l e s and the conservation of mechanical energy among p a r t i c l e s , have already been discussed. On.rare occasions, the teacher was a c t u a l l y mistaken about something. The most obvious instance of t h i s situation was the discussion of the phase change investigation. The topic of discussion was d i f f i c u l t , and i t was a topic beyond the teacher's area of expertise. Mereover, she was neither feeling well nor adequately prepared for the discussion that day. The result was that the students were given incorrect information. When that occurred, some of the more able students were certain the teacher was wrong, and they were very confused and frustrated. Such situations do sometimes occur, p a r t i c u l a r l y in junior secondary science, where the breadth of the program often results in teachers being required to teach topics in which they have l i t t l e expertise. 6.5. Summary This chapter has looked at the instruction provided during the heat and temperature unit. Instruction was examined in terms of a variety of teacher "roles." The f i r s t role to be considered was that of " i n s t r u c t i o n a l manager." The role of 198 i n s t r u c t i o n a l manager included the planning and organization of the a c t i v i t i e s and content of the unit. The teacher indicated that she considered heat and temperature a d i f f i c u l t unit for the students to understand. She f e l t that knowledge of the practical, applications of the topics was important. The teacher considered class discussion or dialogue an important strategy and did not "lecture" to the cl a s s . A description of the class a c t i v i t i e s on the f i r s t day of the unit provided a sample of the teacher's approach to ins t r u c t i o n . She did not draw out the students' prior b e l i e f s about the topics to be studied. However, she did del i b e r a t e l y relate the topics being studied to the students' previous knowledge and experiences, both in school science and outside of school, as she perceived them. She used concrete demonstrations to i l l u s t r a t e abstract phenomena, such as the lead shot to i l l u s t r a t e p a r t i c l e motion. A brief summary of t h e ' a c t i v i t i e s and assignments of the remaining lessons was also presented. The implementation of the teacher's plans, that i s , the actual presentation of the lessons to the students, was investigated by studying the "dialogue" which took place between the teacher and the students during class discussion. Dialogue included any discussion which followed a question-answer format. Ten d i f f e r e n t categories of teacher response to students were described. These categories were grouped into three broad categories, each of which represented a d i f f e r e n t role. When responding to student's answers, the teacher's i n i t i a l response was generally evaluative. The teacher role of "evaluator" included:,acknowledging or accepting a student response, t e l l i n g 1 9 9 the student the answer was incorrect, redirecting the question to another student, and dismissing or ignoring the student's response. The teacher used posi t i v e and supportive feedback, and rarely t o l d a student he or she was wrong. Evaluative responses were usually accompanied by at least one of the other types of response as well. The other roles consisted of the teacher either providing or interpreting science knowledge herself (the role of "provider"), or encouraging the student to rethink his/her answer (the role of "mediator"). The greatest proportion of her responses to students served to draw out and encourage them to think out their ideas about school science. That i s , "mediating" responses occurred more frequently than "providing" responses. The occasions when she redirected questions to other students or provided answers herself usually occurred when time was seen as a constraint. At such times, the teacher appeared to be primarily concerned with e l i c i t i n g the "right answers" to assigned questions. Most of the students appeared to see this as the major goal of the lessons. Their approach to school science suggested they did not expect i t to make sense. Very few students seemed to be concerned about understanding the phenomena preseted in the investigations, readings and discussions. Those who most often challenged ideas that seemed to them to be incorrect or i l l o g i c a l were invariably boys. That i s not to say that some g i r l s may not have had the same concerns. However, i f they did, they did not express those concerns in c l a s s . Jane was a unique student in t h i s class (although there are undoubtedly other "Janes" in many other cl a s s e s ) . She wanted school science to be consistent with her 200 b e l i e f s , but she adopted school science d e f i n i t i o n s and terminology very r e a d i l y . She appeared to be w i l l i n g to accept the authority of school science, but not to accept experimental findings that were contrary to her expectations. In this chapter we have seen that the teacher did encourage students to think out their ideas about school science. Most of her responses to students were categorized as encouraging students to think for themselves. In spite of t h i s , many alternative b e l i e f s persisted at the end of the unit. In the preceding section of t h i s chapter, f i v e factors were i d e n t i f i e d which may be related to the persistence of alternative b e l i e f s . They included: 1) the complexity of the textbook explanations of some concepts, 2) the omission of explanations of some concepts which would have accounted for phenomena observed in the investigations, 3) f a i l u r e to recognize some of the students' al t e r n a t i v e be 1 i e f s , 4) the lack of understanding of the role of a s c i e n t i f i c model, and 5) one si t u a t i o n in which the teacher was mistaken herself. Chapters IV to VI have presented and discussed the findings of t h i s study. In Chapter IV, s c i e n t i s t s ' science, school science and children's science were presented. Chapter V reviewed measures of student learning, i d e n t i f i e d c h a r a c t e r i s t i c s of the more successful learners and i d e n t i f i e d topics which posed p a r t i c u l a r problems for the students. Chapter VI has looked at instruction in terms of teacher roles and the persistent a l t e r n a t i v e b e l i e f s . The concluding chapter 201 of t h i s d i s s e r t a t i o n w i l l provide a brief overview of the study and offer some tentative conclusions and recommendations, based on the findings. 202 CHAPTER VII CONCLUSIONS AND RECOMMENDATIONS 7.0. Overview of the Study Before presenting the conclusions and recommendations derived from the study, t h i s section w i l l b r i e f l y review the rationale and summarize the study. 7.0.1. Rationale Children's b e l i e f s about the par t i c u l a t e nature of matter and about heat and temperature have been investigated in previous studies. This study has b u i l t on and extended the scope of those studies by moving into the classroom. Two months were spent (as a non-participant observer) in a grade nine science c l a s s , investigating the interaction between the students' p r i o r b e l i e f s and learning. The major aim of the study has been to investigate the extent to which alternative b e l i e f s were s t i l l present at the end of the heat and temperature unit, and to attempt to offer some possible explanations for why the students did not revise their a lternative b e l i e f s during i n s t r u c t i o n . 7.0.2. Summary This study has investigated students' ideas about heat and temperature as they studied these topics in school science. A pretest i d e n t i f i e d students' prior b e l i e f s about the part i c u l a t e .nature of matter, heat and temperature, and revealed that many of their prior b e l i e f s were inconsistent with the school science 203 perspective ( i . e . , they were alternative b e l i e f s ) . The same test was also given as a posttest. Eight target students (four males and four females) were selected to represent a range' of prior b e l i e f s . In-depth studies were made of these students' ideas and b e l i e f s , with less detailed data being col l e c t e d on the remaining 15 students in the c l a s s . The investigator observed the nine lessons on heat and temperature, took notes which focussed on the students' a c t i v i t i e s during classes, and taped and transcribed a l l of the lessons. A l l .written work completed by the students was examined, and photocopies were made of a l l of the target students' work. Copies were also made of a l l of the unit test answer sheets. Class dialogue was analysed by categorizing and tabulating a l l discussion and question-answer portions' of each lesson. The students wrote the posttest and the teacher-made unit test on the last day of the study. As has been noted by others (e.g., .Driver and Easley, 1978; and Osborne and Wittrock, 1983), many of the prior alternative b e l i e f s did persist in spite of in s t r u c t i o n . This was the case even when students were c l e a r l y and repeatedly t o l d those ideas were not correct. For example, five students referred to p a r t i c l e s expanding on the posttest. The idea that p a r t i c l e s expand had been discussed several times in clas s , and students were c l e a r l y t o l d that p a r t i c l e s do not expand when matter i s heated. It was also noted that some students provided a "correct" answer about a pa r t i c u l a r phenomenon on the teacher-made unit test (which counted for marks!), yet expressed an 204 alternative b e l i e f about the same p r i n c i p l e on the posttest. Three 'alternative measures of learning were compared. It was seen that the students who achieved the highest marks in science were not necessarily those whose posttest responses revealed that their understanding of the concepts was closest to the school science perspective. Success on the lowest l e v e l questions of the posttest was most closely related to school science marks. Scores on higher l e v e l questions were related to the extent to which students participated in class discussions. School science marks for males and females were not s i g n i f i c a n t l y d i f f e r e n t . However, boys did par t i c i p a t e in class discussions s i g n i f i c a n t l y more than g i r l s , showed greater pretest-posttest gains, and performed better on the posttest, compared to g i r l s . 7.1. Conclusions A number of tentative conclusions can be offered in response to the questions i d e n t i f i e d in the problem statement. Many of these conclusions can best be viewed as tentative hypotheses which may be tested by further studies. 7.1.1. School Science Two major constraints were seen to be influencing school science and the instruction that was provided. One was the complexity of the concepts being presented, and the other was time. Four broad topics were addressed during the heat and temperature unit: 205 1. heat energy and i t s effects on matter, 2. temperature and how i t i s measured, 3. the difference between temperature and heat energy, and 4. heat transfer. The concepts that were presented varied in d i f f i c u l t y . Overall, the teacher had i d e n t i f i e d the heat and temperature unit as the most d i f f i c u l t part of the grade nine science program. Many of the concepts presented could have been d i r e c t l y related to everyday experience. For example, a l l of the students had had experience with a l i q u i d - i n - g l a s s thermometer, had boiled water and seen steam produced, and would probably have had the experience of picking up an object that was very hot to the touch (such as a metal spoon l e f t in a pan of soup heating on the stove). There are many other common experiences that we tend to take for granted, and that could be related to the concepts presented in. t h i s unit. In the curriculum guide, teachers are advised to avoid presenting ideas that are beyond the experiences of the students. The suggestions for teaching science include the following comment: It is important that students avoid discussion of theories which describe observations that are c l e a r l y beyond their  experiences. ... To guide students to [such theories] Ts to f a l s i f y the whole s c i e n t i f i c process. Indeed, students cannot be guided towards such theories: they must be to l d they are true. In thi s case, the authority for the theories i s the teacher not their own observations. The theories then assume the q u a l i t i e s of revelation with the s c i e n t i s t as high p r i e s t or chief magician. (Curriculum Development Branch, 1979, p. 69) The textbook does provide investigations which are intended to ensure that the students do have the necessary laboratory experiences to serve as a basis for the "theories" presented in the unit. For example, two major investigations are provided to 206 demonstrate the difference between heat and temperature. However, the two investigations are themselves very complex and would require careful planning and discussion to ensure that students understand their s i g n i f i c a n c e . The constraint of time resulted in one of the investigations being abbreviated and the other being performed as a demonstration by only one group of students. In the l a t t e r case, the other students in the class were required to do seat work during the investigation, and did not have the opportunity to observe the investigation as i t was being performed. This approach to these complex investigations simply did not provide an adequate opportunity for the students to understand the phenomena being presented. One aspect of the recently completed Science Council of Canada study of school science education consisted of case studies conducted in eight Canadian schools. The f i n a l report made the following comment about the junior secondary classrooms studied: In the junior high school years, science teachers are constrained by the limited time available for covering the subject matter and also by the energy they spend on d i s c i p l i n e and on encouraging good work habits in their students. Thus, content i s given p r i o r i t y over a l l the other science eduction objectives. Science at t h i s l e v e l i s often presented as a catalogue of facts for the students to assimilate as quickly as possible. (Science Council of Canada, 1984, pp. 30-31) Although the teacher did make extensive use of discussion, the limited time did have a major impact on the approach taken for that discussion. It has been noted e a r l i e r that the investigations designed to i l l u s t r a t e the difference between heat and temperature were not adequately discussed in c l a s s . In addition, i t was noted that when the teacher was taking up 207 assignments (laboratory reports and other assigned questions), providing the "correct" answer tended to take precedence over exploring students' b e l i e f s . Although t h i s emphasis on correct answers may be t y p i c a l of what goes on in junior secondary classrooms across Canada, i t is not i d e n t i f i e d as an important goal of school science by most teachers. The summary report of the Canadian portion of the Second International Science Study noted that: ...teachers favoured c u r r i c u l a which: (a) emphasize learning how to learn rather than basic s k i l l s and facts, (b) include a p a r a l l e l students textbook, and (c) use small group rather than whole class instruction (Connelly et a l . , 1984, p. 13). It would seem that although teachers may state a preference for an approach to teaching which does not emphasize learning facts, the r e a l i t y for the average classroom teacher i s large classes, and a curriculum which i s not only conceptually d i f f i c u l t for many students, but i s also too extensive to be taught for -understanding in the time available. CONCLUSION 1: The constraints of time and the complexity of the concepts of heat and temperature resulted in the major emphasis being placed on ide n t i f y i n g the "correct answers." Although the teacher did make extensive use of class discussion, she did not use discussion as a means of ide n t i f y i n g students' prior b e l i e f s . As has been mentioned, t h i s i s a r e l a t i v e l y new approach to teaching which has not been widely implemented in teaching. The suggestion that providing students with s c i e n t i f i c knowledge i s not s u f f i c i e n t to persuade them to abandon their alternative b e l i e f s (Osborne, 1982; Osborne and Wittrock, 1983; and Posner et a l . , 1982) i s supported by the 208 findings of t h i s study. If we wish to replace students' alternative b e l i e f s with s c i e n t i f i c knowledge, the students must be shown that their a lternative b e l i e f s are inadequate and that the s c i e n t i f i c view i s preferable. CONCLUSION 2: The teacher did not i d e n t i f y students' prior b e l i e f s as a starting point for instruction, nor did she emphasize d i s c r e d i t i n g a l t e r n a t i v e b e l i e f s as she attempted to replace those b e l i e f s with the school science view. 7.1.2. S c i e n t i s t s ' Science and School Science Some key concepts have been s i m p l i f i e d and/or otherwise modified for school science, presumably to f a c i l i t a t e student understanding. These include the p a r t i c l e model, the d e f i n i t i o n of temperature as "hotness or coldness" and the school science concept of heat energy. As was shown in Chapter VI where instruction was examined, th i s process of s i m p l i f i c a t i o n appeared to raise as many problems as i t may have resolved. CONCLUSION 3: Inconsistencies between s c i e n t i s t s ' science and school science appear to be attempts to simplify some of the more d i f f i c u l t science concepts in order to f a c i l i t a t e student understanding. These attempts were not successful, as the topics which were s i m p l i f i e d were among those causing the greatest d i f f i c u l t i e s for the students. 7.1.3. Children's Science: B e l i e f s About Heat and Temperature  and the Particulate Nature of Matter The prior b e l i e f s expressed by the students on the pretest and during the pretest interviews were consistent with children's ideas previously described by Albert (1974}, Erickson (1975, 1979, 1980, 1985), Novick and Nussbaum (1978, 1981 and 209 Nussbaum and Novick, 1982), Shayer and Wylam (1981), Stavy and Berkowitz (1980), Tiberghien (1980) and T r i p l e t t (1973), although most of those studies dealt with younger children. Alternative prior b e l i e f s were not completely revised following i n s t r u c t i o n , although a l l but three g i r l s in the class demonstrated gains in scores from pretest to posttest. Doyle (1983) concluded that because students are s t r i v i n g for maximum lev e l s of achievement, i t cannot be assumed that written performance r e f l e c t s b e l i e f s . The findings of thi s study support Doyle's conclusion, as some students expressed one idea on the teacher-made unit test and another on the posttest. CONCLUSION 4: Students' b e l i e f s about correct answers were not necessarily the same as their b e l i e f s about what was true. Alternative b e l i e f s were i d e n t i f i e d from ten topics which were found to be p a r t i c u l a r l y problematic and resistant ,to change. CONCLUSION 5: Alternative b e l i e f s previously described in studies of children's ideas about the pa r t i c u l a t e nature of matter and about heat and temperature were also expressed by the grade nine students in the study, both prior to and upon completion of the unit. 7.1.4. Learning and Instruction Three measures of learning were contrasted: school science marks, posttest scores and pretest-posttest gains. Success in school science was s i g n i f i c a n t l y related to the lowest l e v e l of questions (Level 1) on the posttest. It was not related to posttest questions which required higher l e v e l understanding of heat and temperature concepts (Levels 2 and 3). This finding 210 supports the view that school science is neither taught nor evaluated in a way that encourages meaningful learning. This i s contrary to the espoused aims and objectives of the B r i t i s h Columbia junior secondary science curriculum. Radical changes in the content and/or time a l l o c a t i o n for thi s unit (and probably many other units in the junior secondary science program) would be necessary i f meaningful learning were to be achieved by most students. If meaningful learning is not an achieveable goal of school science, given the current junior secondary program, then curriculum developers should provide a rationale for teaching science as i t tends to be taught--that i s , in a way that requires many students to learn by rote memorizing. CONCLUSION 6: The concepts of the heat and temperature unit, as presented in school science, were not well understood by many of the grade nine students. Students appeared to cope with the demands of the content by memorizing school science d e f i n i t i o n s and facts. CONCLUSION 7: Students who demonstrated highest levels of understanding of the concepts of heat and temperature on the posttest were not necessarily those whose school science achievement was highest. School science marks and pretest scores were not s i g n i f i c a n t l y d i f f e r e n t for boys and g i r l s . The absence of s i g n i f i c a n t differences in achievement of boys and g i r l s in school science marks may be assumed to indicate that no differences e x i s t . However, in thi s study, boys' posttest scores were s i g n i f i c a n t l y higher than g i r l s ' scores, and boys' ' 21 1 gains from the pretest to posttest were also s i g n i f i c a n t l y greater. Boys also participated in class discussions to a s i g n i f i c a n t l y greater extent than did g i r l s . CONCLUSION 8: The absence of s i g n i f i c a n t differences in achievement of males and females in school science does not necessarily indicate that differences do not exist in other measures of learning. In t h i s study, s i g n i f i c a n t gender differences were found in posttest scores for Levels 2 and 3, but not for Level 1. Increased class p a r t i c i p a t i o n was related to superior performance on the posttest. This cannot be assumed to be a cause and eff e c t relationship, however. It may be simply that more able students contribute more to class discussions than those who are less able. The students who did pa r t i c i p a t e most in class discussions (that i s , the students who were e a r l i e r referred to as "the talkers") did take advantage of opportunities to question matters they did not understand, even though that questioning did not always resolve their d i f f i c u l t i e s . Some of the students' a l t e r n a t i v e b e l i e f s were not i d e n t i f i e d by the teacher because many students did not ask such questions. CONCLUSION 9: The analysis of covariance revealed that student p a r t i c i p a t i o n in class discussions accounted for a s i g n i f i c a n t amount of variance in the posttest only for Level 3 questions. Persistant a l t e r n a t i v e b e l i e f s were i d e n t i f i e d from ten topic areas. Although the teachers' guide i d e n t i f i e d many of 212 these topics as being problematic for students, not a l l d i f f i c u l t i e s were i d e n t i f i e d . When the instruction provided for these topics was examined, one or more of five factors appeared to be involved in most cases: 1. The school science explanations of some heat phenomena were presented in terms of mechanical energy, a school science concept which was not well understood by the students. 2. The s c i e n t i s t s ' science explanation of the phenomenon was omitted, either by the teacher and/or the textbook, presumably because i t was thought to be too d i f f i c u l t for the students to understand. 3 . The alternative b e l i e f s had not been i d e n t i f i e d by the teacher, the curriculum guide or the teachers' guide. 4 . The students were unable to relate a s c i e n t i f i c model to the phenomenon which was being explained. 5. The teacher attempted to provide an explanation that the students would understand, but the explanation was not successful. Alternative b e l i e f s which appear to be related to the omission of s c i e n t i f i c ideas included the b e l i e f that the c h a r a c t e r i s t i c property of density accounts for the phenomena of di f f e r e n t materials having d i f f e r e n t s p e c i f i c heat capacities and d i f f e r e n t thermal c o n d u c t i v i t i e s , and the b e l i e f that the temperature of matter always increases when matter i s heated. Many students seemed unconcerned about school science t e l l i n g them their own b e l i e f s were incorrect. However, some of the more able students appeared to be s t r i v i n g unsuccessfully to find explanations which made sense to them. In p a r t i c u l a r , Joe, 213 Alan and Brian were v i s i b l y frustrated when they could not understand school science explanations. None of the students indicated a good understanding of the school science explanation of these concepts. CONCLUSION 10: The more competent students were frequently frustrated by observations which were not expected, which they did not understand and which were not adequately explained. CONCLUSION 11: The more competent students were frequently not s a t i s f i e d with ove r l y - s i m p l i f i e d explanations which were contrary to the students' prior knowledge of s c i e n t i f i c phenomena. There were two alternative b e l i e f s which were not i d e n t i f i e d by the teacher. One was the be l i e f that hot and cold are d i f f e r e n t e n t i t i e s . The other was the be l i e f that temperature represented a measure of heat during the phase change investigation. Neither of these potential problems was mentioned in the teachers' guide. CONCLUSION 12: Some alternative b e l i e f s were not i d e n t i f i e d by the teacher throughout the period of i n s t r u c t i o n . There was no evidence that the use of models f a c i l i t a t e d understanding for any of the students. To the contrary, for some i t raised d i f f i c u l t i e s , as the students appeared to have a very limited view of the role of a s c i e n t i f i c model. For example, the school science model of the p a r t i c l e as the smallest unit of matter caused d i f f i c u l t y for Brian and Joe, and possibly others who did not speak out. Rejecting t h i s model 214 appeared to account for Brian not abandoning his b e l i e f that p a r t i c l e s could expand. CONCLUSION 13: Many students did not understand the relationship between a s c i e n t i f i c model and the s c i e n t i f i c phenomenon represented by the model. No teacher i s immune to an "off day" and, unfortunately, one of the most d i f f i c u l t ideas was discussed on one such day for t h i s teacher. The d i s t i n c t i o n between heat and temperature was never successfully resolved for most of these students, and i t was not presented well during class discussion. The teacher appeared to be unsure of some of the ideas herself. CONCLUSION 14: Some of the d i f f i c u l t i e s encountered by the students could be .attributed to the teacher providing incorrect information about a topic she did not understand well herself. 7.2. Recommendat ions A number of recommendations can be derived from the conclusions of the study. The recommendations f a l l into two areas: recommendations pertaining to teaching school science, and recommendations for further research. 7.2.1. Teaching School Science 1. Teachers should establish strategies to e l i c i t students' p r i o r b e l i e f s about science topics, so as to be able to address these alternative b e l i e f s during i n s t r u c t i o n . In order to understand students' b e l i e f s , i t i s important to i d e n t i f y the reasoning behind wrong answers. 2. Teachers should establish . strategies to e l i c i t p a r t i c i p a t i o n by a l l students during class discussions. 215 3. Teachers should s t r i v e to encourage g i r l s to p a r t i c i p a t e in • class discussions to a greater extent, and to relate school science to contexts with which g i r l s can i d e n t i f y . 4. Teachers should be encouraged to use evaluation techniques which place greater emphasis on students' understanding of science concepts, with less emphasis on knowledge which can be acquired by rote learning. 5. If s i m p l i f i e d models, such as the p a r t i c l e model, are to be used, teachers must be prepared to explain and j u s t i f y their use to the s a t i s f a c t i o n of students who question the accuracy and/or v a l i d i t y of such models. 6. More e f f o r t i s needed to relate school science to students' prior experiences, in an e f f o r t to eliminate the perceived d i s t i n c t i o n between school science and the "real world." If teachers are to implement the above recommendations, additional support from a number of sources w i l l be required. 7. Research conducted throughout the western world has shown that school children of a l l ages tend to express similar a l t e r n a t i v e b e l i e f s about heat and temperature concepts. Findings of studies on students' alternative b e l i e f s about a l l science topics should be disseminated both to curriculum developers and to classroom teachers. 8. More support should be provided for teachers who are required to teach d i f f i c u l t concepts such as heat and temperature, p a r t i c u l a r l y when the topics are beyond the teacher's area of expertise. Additional i n s e r v i c e - t r a i n i n g may be one such support. 216 7.2.2. Research 9. There i s a need for further classroom studies which w i l l investigate strategies for i d e n t i f y i n g prior b e l i e f s and determine the e f f e c t s of basing instruction on students' prior b e l i e f s . 10. Further study i s needed to examine the differences in class p a r t i c i p a t i o n and learning by male and female students. 11. The finding that p a r t i c i p a t i o n in class discussion was related to success on higher l e v e l posttest questions should be further investigated. 12. Further investigations are needed to examine students' understanding of models used in school science. 217 REFERENCE NOTES 1. Kozlow, M. Data provided to B. 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If you wish to go over your re s u l t s with one of us, we w i l l arrange to meet with you. 1 8 cm 4 cm O c m Temperature Temperature A. 0°C is the temperature of melting i c e . 1. What i s the temperature of b o i l i n g water? °C 2. On the second diagram above, draw in the l e v e l that the l i q u i d would be i f i t s temperature was 50°C. 3. Why does the l i q u i d r i s e when the flask i s in b o i l i n g water? 4. Fred explains i t by saying "hot water r i s e s . " Do you 1 This introduction was omitted for the posttest. 225 t h i n k t h i s i s a good e x p l a n a t i o n ? yes / no Why do you thin k i t i s or i s n ' t ? 5. What i s the temperature i s the f o u r t h diagram? °C 6. I f you h o l d the f l a s k u n t i l the red l i q u i d reaches your body temperature, what w i l l the h e i g h t be? Draw in the l e v e l on the f i f t h diagram above. We don't expect an exact answer, j u s t a good guess. 7. I f you l e t the f l a s k stand i n the classroom, what would the height be? T h i s time draw i n the l e v e l on the s i x t h diagram. 8. What would the he i g h t of the red l i q u i d be at 200°C? cm 9. Can you say what the h e i g h t might be at 1000°C? cm E x p l a i n your answer. 10. Make a rough guess at the temperature of the f o l l o w i n g , and g i v e a short reasonr example: Temperature needed to bake bread. .£.QP.°C r ^ ^ ^ f l - ' . t^^fV^'. j ^ i r V ^ V i ) f r y i n g c h i p s °C i i ) a r a b b i t ' s body °C I i i ) f r e e z i n g mercury °C ........ - $00°c - - -B. I f you i.eat a l a r g e n a i l to 500°C, and then drop i t i n t o a g l a s s of water which i s a t room temperature (18°C); what do you t h i n k w i l l happen t o : X3& 1. the temperature of the n a i l ? 226 2. the temperature of the water? 3. Explain how t h i s happens. 4. Make a guess at the temperatures of the water and the n a i l after the n a i l has been in the water f o r : water n a i l Before adding n a i l to water 18° 500° After 1 minute After 5 minutes After 10 minutes After 15 minutes After 30 minutes If you have a large beaker of b o i l i n g water, and a small beaker of b o i l i n g water, 1. which beaker has the most heat? 2. which beaker i s the hottest? 3. If you mix water from both beakers into a larger beaker, w i l l the temperature of the mixed water be greater, less or the same as before mixing? Explain your answer. In a classroom, where would you expect to fin d the warmest a i r ? near the c e i l i n g / in the middle / near the floor Explain why you chose that answer: 227 If you heated a can with a balloon on top of i t , what would happen to the balloon?' 1. Why? 2. Would you expect the balloon to fe e l warm? yes / no 3. Why? 4. 5. If you turned the can upside down, what would happen when the pan was heated, and why? Would you expect the balloon to fe e l warm now? yes / no If you answered YES, say how the heat got there. If you answered NO, say why the heat does not get there. Can you think of two objects (A and B) where t h i s would be true: "A i s hotter than B, but B has more heat than A." Say why: A B 228 The pins are stuck on to the metal tube with wax. After one end of the tube has been heated for a while, one of the pins f a l l s off.' 1 . 2. TT \ 2. 3 Which pin do you think f a l l s o f f ? Why does i t f a l l off? 3. Would you expect a l l of the pins to f a l l off at the same time? Explain why. 4. In what way does heat move along the tube? 5: If you used the same Q flame to heat a s o l i d rod of the same material, would i t take: more / less / the same time before the pins dropped off? Explain why: 6. If you used a glass rod instead of a metal one, would the pins drop off faster / slower / after the same time Explain. If you have a large ice cube and a small ice cube in water, the small ice cube w i l l melt f i r s t . 1. Are both ice cubes at the same temperature? yes / no 229 Why do you think the small ice cube melts f i r s t ? Do you think both ice cubes need the same amount of heat to melt them? Explain your answer. What do you think happens to the temperature of the water as.the ice melts? Jane says, "If you leave the ice out in the a i r , i t w i l l melt anyway, so that you don't need any heat." Do you agree? yes / no If YES, how could you stop i t melting? If NO, where does the heat come from? And, how does i t get into the ice? \ / \ A large solar panel can be connected either to a large water tank or — to a small water tank. 1 . Which tank do you think w i l l store the most heat? large / small / both the same 2. Explain why. 3. Which tank do you think w i l l have the hottest water? large / small / both the same 4. Explain why. 230 J. A metal rod i s fixed at one end, and the other end rests on a needle. A pointer i s attached to the needle, and there i s a d i a l fixed near the other end of the pointer. CLAWP n a L 1. Soon afte r the attached end of the rod i s heated, the pointer s t a r t s to move. Why? 2. Look at your answer, i t . Try to explain how the heat does 3. If the rod were cut in half , and a piece of insulator fastened between the two halves, what would happen when the rod was heated? 4. Jim says, " I t ' s the heat which makes the pointer move, so i f you go on heating for a very long time, the pointer w i l l keep on moving." What do you think? 5. What rod? w i l l happen when the heat i s removed from the Why? 231 O i l pipes in the hot desert have bends in them so that when they expand they do not break. Why does heat make them expand? This i s a special box which has two sections. The wall between the two sections can be removed. 1. We f i l l side A with water at 25°C-and side B with the same amount of water at 25°C. When we take out the wall in the middle, the water from A and B mix. What w i l l be the temperature of the water afte r i t has mixed? °C 2. If we f i l l side A with water at 20°C and side B with the same amount of water at 40°C, what w i l l the temperature be when they mix? °C 3. If you wanted the heat from A and B to even out, without l e t t i n g the water mix, what material would you use for the wall? 4. How does heat get through the wall? 5. If we f i l l A with water at 30°C and we only f i l l 1/3 of B with water at 10°C, what w i l l the temperature be when they mix? °C 232 L. If you leave a shovel outdoors on a frosty night, the metal feels much colder than the wooden handle. 1. Why does the metal f e e l colder than the wood? 2. Suppose the temperature of the metal is -3°C, what do you think the temperature of the wood might be? °C 3. What do you think the a i r temperature might be? °C t 233 A P P E N D I X g PROTOCOL FOR STUDENT INTERVIEW I w o u l d l i k e t o a s k y o u a b o u t some o f t h e q u e s t i o n s o n t h e p r e -t e s t . I may a s k y o u t o e x p l a i n a l i t t l e more a b o u t y o u r a n s w e r , o r I may a s k y o u t o t h i n k a b i t m o r e a b o u t t h e q u e s t i o n t o s e e i f y o u h a v e c h a n g e d y o u r m i n d a b o u t t h e a n s w e r . Y o u r a n s w e r s may b e d i f f e r e n t t h a n when y o u w r o t e t h e t e s t , b u t t h a t ' s O . K . We w o n ' t t a l k a b o u t a l l o f t h e q u e s t i o n s , j u s t some o f t h e m . H e r e i s a b l a n k t e s t s o y o u c a n f o l l o w a l o n g w i t h me . Do y o u h a v e a n y q u e s t i o n s ? Do y o u m i n d i f I t a p e o u r c o n v e r s a t i o n ? A. On t h e f i r s t s e t o f q u e s t i o n s t h e r e a r e s i x d r a w i n g s o f a f l a s k t h a t i s f i l l e d w i t h a r e d l i q u i d a n d h a s a l o n g t u b e s t i c k i n g o u t o f t h e t o p . T h e f l a s k i s a t a d i f f e r e n t t e m p e r a t u r e i n e a c h d r a w i n g , a n d we s e e t h e l i q u i d a t d i f f e r e n t h e i g h t s i n t h e t u b e s . 1 . I f t h e r e i s t h e same a m o u n t o f l i q u i d i n e a c h c a s e , why d o e s i t go h i g h e r i n t h e t u b e i n some d r a w i n g s t h a n i n o t h e r s ? ( F o r e x a m p l e , h e r e (#1) i t i s l o w e r a n d h e r e (#3) i t i s n e a r t h e t o p . Why i s t h a t ? ) * 4. I n q u e s t i o n 4 i t s a y s t h a t F r e d s a y s t h e l i q u i d r o s e i n t h e t u b e b e c a u s e " h o t w a t e r r i s e s . " I s t h a t a n o t h e r w a y o f s a y i n g w h a t y o u j u s t t o l d me? ( I f F r e d was s i t t i n g b e s i d e y o u How w o u l d y o u e x p l a i n t o h i m why h i s a n s w e r i s n ' t c o r r e c t ? ) I n d r a w i n g s 5 a n d 6 y o u w e r e a s k e d t o d r a w b o d y t e m p e r a t u r e ^ Q u e s t i o n s i n p a r e n t h e s e s w o u l d o n l y b e u s e d i f s t u d e n t h a s a p a r t i c u l a r m i s u n d e r s t a n d i n g . 23^ and room temperature. What temperatures d i d you draw? (11 . At the top o f the next page you were asked to guess at some temperatures. One o f them was . What were you t h i n k i n g when you chose °C?) Now w e ' l l look a t the hot n a i l i n the beaker o f water. You thought the temperature o f the n a i l would drop and the water would get warmer. 3 . How i s i t t h a t those two t h i n g s change temperature l i k e t h a t ? When you say (the heat goes from the n a i l to the water), what i s happening i n the metal and i n the water as t h e i r temperature changes? What's a c t u a l l y c a u s i n g the temperatures to change? How does heat get from a hot t h i n g to a c o o l e r t h i n g ? Does t h i s always happen i f a h o t t e r t h i n g i s put i n t o a c o o l e r t h i n g ? What c o n d i t i o n s would be n e c e s s a r y f o r the n a i l and the water to s t a y at theisame temperature? 4. What happens to the temperature of the water a f t e r the n a i l i s put i n ? How does the temperature of the n a i l compare to t h a t o f the water? What would t h e i r temperatures be s e v e r a l hours l a t e r ? Now l e t ' s loofc at the q u e s t i o n about the l a r g e and s m a l l beakers. Both c o n t a i n b o i l i n g water. You s a i d has the most heat and i s the h o t t e s t . ( i f same: Is there any d i f f e r e n c e i n the meaning of these two q u e s t i o n s ? ) 235 ( i f d i f f e r e n t : How would you explain how can he hotter, i f has more heat?) 3. ( I f you combine the b o i l i n g water from the small beaker and the b o i l i n g water from the large beaker, you said the temperature would be . Why would i t be ?) (You said the warmest a i r i n a classroom i s . Why do you think that?) The next set of questions i s about an empty metal can. It has only a i r i n i t and a balloon i s placed over the opening. Now no more a i r can get i n or out of the can. 1. F i r s t we place the can upright and heat the bottom. (We won't l e t i t get hot enough to melt the balloon, so what would happen to the balloon before i t could melt?) (What w i l l be happening to the a i r inside the can as we heat the can?) 2. ( W i l l i t get warmer? As the a i r inside the can gets warmer, what w i l l happen to the balloon?) (Why would the balloon be inflating/blowing up?) 4. In the second drawing we've taken another can, because the f i r s t can was too hot. This time i t ' s upside down, so the balloon i s at the bottom. What w i l l happen to the balloon t h i s time? Does i t get warm? (What would the air aside the can be doing while the can i s being heated?) Are there any possible ways that you could have two objects, and one of them would be hotter, but the other one would have more heat? Can you give me an example? 2 3 6 The next diagram shows a metal tube being heated. Three pins are fastened to the tube with wax. What causes the f i r s t pin to f a l l o f f ? (Why does the tube getting hot make the pin f a l l off?) How does the heat get from the burner to the other end of the tube? (Does i t go through the hole i n the tube, or through the metal, or along the outside of the tube, or how?) How does heat move through a i r ? through metal? Do you know the name for t h i s process? (of heat moving through metal?) 6 . You said that with a glass rod the pins would drop o f f faster/slower. Why do you think so? In these next questions we have a large and a small ice cube i n a beaker of water, You said they are both at the same temperature, but that the small one would melt f i r s t . How i s that possible? ( 3 . Then you said they both need the same amount of heat to melt . them. One of the other students sai d that the large ice cube needs more heat, because i t i s larger and i t takes longer to melt? Do you agree with that? Why/not?) How could you explain your view to another student? 5 . Jane says the ice cube w i l l melt i n the a i r , so that means heat i s n ' t involved when i t melts. (Jane doesn't mean you don't have to add any heat. She means that there i s no heat involved at a l l when the ice cube melts.) Do you agree with Jane? The next question i s about solar heating. Do you have any idea how so l a r heating works? (The sol a r panel i s made of a long tube of metal that twists back and f o r t h , and i s f i l l e d with water. 237 The tube i s connected to a tank, and the water i s pumped from the tank through the tube, and back to the tank. When the water i s i n the panel i t i s heated by the sun. The tank can then be used i n place of a water heater.) Suppose we have two i d e n t i c a l houses s i t t i n g side by side, and they have i d e n t i c a l s o l a r panels. The sun i s shining on both panels i n the same way. Suppose one house has a large water tank and the other house has a small tank. On a sunny day you go to check the two water tanks. (Repeat questions 1 to 3 ) 4. (Why are they the same?) or (Why doesn't the hottest water have the most heat?) (IF NO ANSWERS TO 1 - 5 i n part J, deal with 6 f i r s t — r e t u r n to others i f student seems to grasp the idea of expansion) 6.' Could you explain to me again why heat makes o i l pipes i n the hot desert expand? (Does a l l metal expand when heated?) In the diagram above, the metal tube i s being heated, and i t i s expanding. This p l a s t i c l i d i s l i k e the d i a l i n the diagram. I f I r o l l the pin just a t i n y b i t , the d i a l turns much more. This allows us to detect a very small movement i n the metal tube. Do you see how i t works? In the drawing, the rod i s heated and i t expands. When i t expands i t pushes on the pin, just l i k e my finger did, and.the pin r o l l s a l i t t l e b i t , causing the pointer to move. (IF STUDENT IS STILL UNSURE AT THIS POINT, GO ON TO THE NEXT SECTION) 2 . Why does the rod push the needle when i t i s heated? 3 . W i l l the pointer move i f the rod has an insulator i n i t l i k e i n t h i s diagram? W i l l i t move the same amount as before/or 2 3 8 l e s s / o r more? 4 . I f the rod was heated for a long time, would the pointer keep moving? ( i f yes; Another student was c e r t a i n i t would soon stop moving. What would you say to him/her to explain your answer?) ( i f no: What would you say to Jim to explain why the pointer doesn't keep moving?) 5 . What would happen to the pointer i f we take the "burner away? Here i s the box with the two sections and the wall between them can be taken out. 3. #3 asks what material you would use so the heat from A and B would even out without removing the wall. You said . 4 . Why did you think would be a good material to use? (Can you think of a material that would allow the heat to go d i r e c t l y from B to A THROUGH the wall?) 5 . For #5 you gave °C as your answer. How did you f i n d that answer? (Did you make an estimate?) The l a s t section concerns the shovel l e f t outdoors on a fr o s t y night. Have you ever noticed that when i t ' s cold outside that metal f e e l s colder than most other substances? 1. Why does the metal f e e l colder? 2. Suppose you Ha<i a s p e c i a l thermometer so you could measure the temperature of both the metal and the wooden handle. The metal i s -3°C. What would the temperature of the handle be? What would the a i r temperature be? Thank you very much for your help. 239 APPENDIX C HEAT AND TEMPERATURE UNIT TEST 1. Explain the difference between heat energy, mechanical energy and temperature. (6:7)* 2. Give three examples of transformations to heat energy. (3:15) 3. Using a diagram explain the difference between a bar of iron at room temperature and at 100°C. Show the p a r t i c l e s . (6:5) 4. If a cylinder of gas contains 30 p a r t i c l e s and each p a r t i c l e has 3J mechanical energy, how much heat energy does the gas have? (2:20) 5. Explain how you could c a l i b r a t e a mercury thermometer. (5:3) 6. Explain how a bi m e t a l l i c s t r i p can be used as a switch. Use a diagram. (5:12) 7. L i s t three factors which a f f e c t the heat energy of an object. (3:13) 8. L i s t three ways heat energy may be transferred. (3:17) 9. Using the p a r t i c l e model explain how conduction occurs. (5:12) 10. At night, the land near the sea cools down to a lower temperature than the sea. Therefore the a i r above the land i s cooler than the a i r above the sea. Make — a drawing. Using arrows ~ — show the d i r e c t i o n of the convection current. (3:7) 11. Describe the clothi n g you might wear at -60°C on a sunny day. Explain how i t would keep you warm. (3:4) 12. How does the sun's energy reach us? (1:17) 240 Suppose you were outside on a hot day when the temperature i s 30°C. Which r a d i a t e s more—your body or your surroundings? What kind of c l o t h i n g should you wear to stay c o o l ? Why? (5:5) Y) where X=number of marks f o r the ques t i o n , and Y=number of students r e c e i v i n g f u l l marks on the question 241 APPENDIX D CONCEPTUAL BIOGRAPHY: JANE Jane was i d e n t i f i e d by the teacher as the best student in the class. Her f i n a l mark in science was 94%, the next highest mark being 88%. She spoke out in class more than most other students, both in response to questions posed by the teacher, and to ask about things she did not understand. The teacher frequently acknowledged that Jane had a "good question" and never put off dealing with her questions i n d e f i n i t e l y . If there was no time available at the moment, the teacher told Jane when she would be able to discuss i t with her. Jane was one of a group of seven g i r l s (of the 14 g i r l s in the class) who sat in a cluster and worked closely together. Other students in the class, p a r t i c u l a r l y the other six g i r l s in this group, frequently asked Jane for assistance. If Jane and any other student expressed c o n f l i c t i n g opinions, the class believed Jane. Even capable students yielded to her opinion, including on occasions when she was not correct. Thus i t appeared that the students also considered Jane to be the most knowledgeable student in the class. Jane's written work was completed neatly and on time. The wording of her answers tended to be almost exactly as presented in the text or by the teacher in class. She was one of the few students to submit a complete set of written assignments to the observer. In short, the overall impression was that Jane was an ideal student. The Particulate Nature of Matter On the pretest Jane understood that matter is composed of par t i c l e s which are further apart in hotter matter than in cooler matter. For example, she said that a l i q u i d r i s e s in a tube when i t i s heated "because i t is heated and i t expands as the p a r t i c l e s in the l i q u i d spread apart." The o i l pipes in the desert expand "because the pa r t i c l e s get hotter and spread apart, therefore expanding the material (pipes)." Heat Energy and Its Effects on Matter On the pretest and during the f i r s t interview, Jane appeared uncertain about the nature of heat. During the interview she indicated heat was "warmth" caused by burning or f r i c t i o n or "something l i k e that." However, in reference to questions dealing with heat transfer she favoured a f l u i d view. For example, in response to a question about how heat i s transferred from a hot n a i l to the water in which i t i s submerged, she replied, "...and so i t [heat] moves along, I don't know, I guess maybe between the p a r t i c l e s of water or in the p a r t i c l e s of the water and warms i t up." That i s , on the pretest and subsequent interview Jane did not seem to know that 242 heating matter causes an increase in the mechanical energy of the p a r t i c l e s . She confined her description to saying the p a r t i c l e s were further apart. When explaining thermal expansion of a metal rod she said, "the p a r t i c l e s of the material speed up." Again, she gave no indication of relating the increased speed to an increase in the mechanical energy of the p a r t i c l e s . On Day 2, during a class discussion about how a mercury thermometer works, Jane explained, " i t gets heated up and the p a r t i c l e s move faster and farther apart and so i t has to expand." Once more, the energy i t s e l f i s not mentioned. During thi s particular discussion, Jane provided most of the answers to questions posed by the teacher. Later that period the b a l l and ring phenomenon was demonstrated by the teacher. Two other students stated that the b a l l expanded when i t was heated because the p a r t i c l e s expanded. Jane was then c a l l e d upon to give her interpretation and again said the p a r t i c l e s speeded up and moved apart. The teacher then asked, "How do they speed up? What kind of energy are they gaining?" Jane and several others responded "mechanical." Thus, at this early stage in the unit, Jane needed a probe from the teacher before relating heating to an increase in the mechanical energy of the p a r t i c l e s . On Day 7, during the discussion of Investigation 1.45 (Heat energy and temperature in phase changes), the teacher asked, "What i s heat energy?" Jane quickly responded, "the t o t a l sum of a l l the mechanical energy of the p a r t i c l e s . " By then the probes were no longer required. On the posttest questions about solar heating panels, Jane said the water in the large tank would store more heat because i t has "more p a r t i c l e s to gain mechanical energy," and the water in the smaller tank would be hotter because the "average mechanical energy of a p a r t i c l e would be greater." Here she c l e a r l y indicated an understanding of the school science d e f i n i t i o n of heat. She distinguished between heat and temperature in terms of kinetic molecular theory. Jane also revealed some confusion about the d i s t i n c t i o n between heat and cold. She appeared to think of cold as being a d i s t i n c t entity in i t s e l f . For example, compared to a smaller ice cube, a large ice cube w i l l "keep the cold in more," and metal feels colder than wood because (on the pretest) " i t conducts heat and cold well" and (on the posttest) " i t conducts cold better." The question of the nature of cold i s not addressed in the text, nor was i t discussed in class. Apparently i t i s assumed that students w i l l understand the nature of "cold" i f they understand the nature of "heat." Jane's confusion on the matter suggests that t h i s is not a v a l i d assumption. Temperature and How It Is Measured Jane experienced no d i f f i c u l t y answering questions related to temperature and temperature scales on either the pretest or the posttest. 243 The Difference Between Temperature and Heat Energy Jane did not c l e a r l y distinguish heat and temperature on the pretest or during the interview. Her d i f f i c u l t i e s on this d i s t i n c t i o n had largely been resolved by the posttest. For example, during the interview concerning the large and small beakers of boiling water, Jane said that the large beaker would be hottest because i t had more water and therefore would give off more heat. On the posttest she recognized that neither beaker would be hotter because "both sets of p a r t i c l e s have the same mechanical energy." When asked to give an example of two objects such that one is hotter and the other has more heat, Jane's posttest response was based on a kinetic theory explanation (which was taken d i r e c t l y from a problem that had been assigned e a r l i e r ) . She responded, "a cup of boi l i n g water is hotter because average mechanical energy of p a r t i c l e [ s i c ] i s higher" and "swimming pool has more heat energy because i t has so many more p a r t i c l e s . " On the pretest question about the large and small ice cubes Jane said the small ice cube was warmer and would melt f i r s t because " i t i s less massive and has higher temperature." Both cubes would need the same amount of heat to melt, but the larger one would take longer to m e l t — i t keeps the cold i n . When questioned during the interview she reasoned that the ice cubes would be the same temperature when they were in the freezer and when f i r s t put into the water, and that they would require di f f e r e n t amounts of heat to melt them. She seemed "ready" to understand what was happening to the ice cubes, but had not previously thought i t through. On the posttest she provided a kinetic explanation—the small ice cube melts f i r s t because "there are less p a r t i c l e s to spread apart." However, she s t i l l revealed some confusion (possibly due to haste and not care f u l l y reading the question?) when she said that both cubes need the same amount of heat to melt but the larger one w i l l take longer to melt. She was evidently confusing heat and temperature in this statement. Heat Transfer Jane's explanations of heat transfer changed greatly from the pretest to the posttest. Conduction Jane was i n i t i a l l y unclear on the nature of conduction. On the pretest she said, "there i s so much heat from the n a i l that i t would diffuse through the water." During the interview she speculated that heat may move "between" p a r t i c l e s of water and "through" the par t i c l e s of a metal. Like some other students, Jane appeared to believe that the turning of the d i a l on the metal rod expansion apparatus was due to p a r t i c l e s speeding up and h i t t i n g the needle more ( i . e . , agitating i t ) , thus causing i t to move. She was aware that some materials are better conductors than others, but as mentioned e a r l i e r , she referred to conduction of heat and cold as i f these were two different 244 "things". She did not give a kinetic explanation of conduction on the posttest. However, on the unit test given by the teacher (written during the same class period as the posttest, but which "counted" as part of her mark in science) the following question was asked: "Using the p a r t i c l e model, explain how conduction occurs." With this additional probing, Jane replied: When one end of an object is heated, the p a r t i c l e s at that end gain mechanical energy and speed up. This causes them to bump/collide into "neighboring" p a r t i c l e s and these l a t t e r p a r t i c l e s gain mechanical energy. These in turn bump/collide the p a r t i c l e s farther along the object, and in this way, heat energy is conducted. Convection Like the other students, Jane was aware that "hot a i r r i s e s . " On the pretest she predicted that the warmest a i r would be near the c e i l i n g "because hot a i r p a r t i c l e s are very l i g h t so they rise to the top of the room." She apparently confused the density of the a i r with the mass of the p a r t i c l e s themselves. On the posttest she responded, "because hot a i r is less dense than cold a i r and i t would r i s e . " She knew that the hot a i r r i s e s , but expected i t to stay at the top of i t s container, rather than recognizing that an unlimited amount of a i r cannot keep expanding and r i s i n g when i t i s heated. For example, on the pretest question about the syrup can with the balloon on the bottom of the can, she said, the "balloon would be limp because the hot a i r would ri s e up, not go down." This belief was repeated in the interview. On the posttest she replied, "the balloon would expand because the a i r expands and has nowhere to go but down." However, she did not expect the balloon to feel warm "because the hotter a i r rises to the top of the can." She gave no indication of recognizing this situation as an example of convection. This i s p a r t i c u l a r l y surprizing, because only two days e a r l i e r she had related the thermal expansion of a f l u i d to convection during a class discussion. The teacher had asked for someone to "explain how convection would work." Jane replied: If you have some water and you heat up part of that water, and the water that you heat up, the p a r t i c l e s w i l l move farther apart, the water w i l l have more heat energy, so the heated water gets lighter than the cold water, so the cold water i s heavier and i t pushes the hot water and so that's how i t ' s moving around. Although th i s explanation i s more accurate than Jane's posttest description of the a i r moving in the heated can, there are s t i l l some problems. Density and mass are confused and there is the notion of the cold water "pushing" the hot water. On the assigned questions about convection Jane also referred to colder a i r pushing "less dense warm a i r up." On another of the assigned questions, she stated that "heat energy always rises naturally, and w i l l not go in any other direction unless i t is forced to by unaturally [sic] means." This confusion may have 245 i t s origins in the class discussion. The teacher had stressed the point that one d i s t i n c t i v e feature of convection is that heat is always transferred upwards in convection, unlike conduction and radiation where heat can be transferred in any direc t i o n . The assigned reading on convection explained convection in relation to both hot a i r and hot water heating systems. Moreover, on the unit test Jane correctly diagramed convection currents of a i r masses over a land-sea interface. In spite of these varied ways of looking at convection, Jane appears to have a limited understanding and to be unable to transfer that understanding to a different system, namely the convection of a i r in the closed can, as was required on the pretest/posttest question. Radiation On the pretest Jane expressed the belief that a larger amount of b o i l i n g water i s hotter than a smaller amount because i t gives off more heat. This belief probably derived from a p a r t i a l understanding of radiant energy. On the posttest Jane said that both beakers of boiling water were the same temperature. On the unit test Jane responded that the sun's energy reaches the earth by radiation, that a human body radiates more heat than an object which has a temperature less than body temperature and that color influences the amount of radiant energy that is reflected or absorbed by an object. Conclusion In conclusion, Jane's achievement in science, her performance on the pretest and posttest, and her status among her classmates, a l l support the teacher's perception of Jane as the "best student" in the c l a s s . However, in spite of th i s , Jane s t i l l revealed some basic misunderstandings about heat upon completion of this unit. Moreover, Jane showed no evidence of a particular f l a i r or feeling for science (unlike Alan and Joe, who appeared to be genuinely intrigued by findings they had not anticipated). Jane's answers to questions seemed drawn d i r e c t l y from the text or from the teacher's comments in class. She appeared to accept the school science view without question. Only when probed did she show signs of puzzling out something for herself. She was not inspired to question unexpected results, but rather assumed something must be wrong with the experiment. 246 APPENDIX E THE PHASE CHANGE INVESTIGATION (INV. 1.45) Jane, Joe and Alan conducted Investigation 1.45 (Heat Energy and Temperature in Phase Changes) as a "demonstration" for the class. The procedure was to heat ice cubes and record the water temperature every two minutes u n t i l half of the water had boiled away. The students had been not n o t i f i e d in advance that they would be doing the laboratory and hence the f i r s t 15 minutes of the period were spent reading the directions and setting up their notebooks. The teacher then asked, "May I have a volunteeer to be the s c i e n t i s t for the day? Do this experiment?" One g i r l suggested Jane and she declined. Joe volunteered and the teacher agreed to have him do i t . The teacher then asked for a volunteer recorder. Again, Jane's name was proposed; again, Jane declined. However, after some discussion the teacher persuaded Jane to agree to record the data. As Joe was setting up the apparatus, Alan began to assist him, and took over the task of timing the observations. Meanwhile the other students were told to complete their preparation while Jane, Joe and Alan did the investigation. Jane recorded the data on the overhead projector while Joe took the readings and Alan did the timing. The data was not as the students expected, and during the investigation there was a great deal of discussion among the three about this problem. The f i n a l version of the data, as recorded by Jane, d i f f e r e d somewhat from Joe's actual readings. The f i r s t three readings were 2°, 6°, and 4°. Jane said the t h i r d reading could not be 4°, and protested vigorously. Joe and Alan discussed the dilemma and speculated that the position of the thermometer with respect to the heat source might account for this unusual data. Jane continued to protest, and Joe suggested reversing the two readings, but instead Jane omitted the 6° reading, and recorded a temperature of 2° for the second reading. She then omitted the time "0" reading completely. A l l went well u n t i l the ice had melted and the temperature increased from 17° to 35° during a two-minute i n t e r v a l . Jane refused to accept the l a t t e r reading. Alan: Lookat! A l l the ice melted! Joe: A l l the ice melted? In between eight and ten minutes—no, in between 10 and 12 minutes. Jane: 11 and 12 minutes? Joe: [muttering to himself, trying to decide just when the ice melted] 247 Jane: Between 10 and 12, Joe? Joe: Yeah. Joe: [about a minute later] 35! Jane: What i s i t ? Joe: It's 35 right now. Jane: [sarcasticly and laughing] Oh right Joe. Joe: It i s . Come and look. Jane: It went from 17 to 35 [her tone indicates d i s b e l i e f ] . Alan: It is 35. Joe: O.K. Put down, umm, 20. Jane: 20. Alan: Yeah, that looks good. Joe: It i s 35. Jane: Oh yeah, you guys [she s t i l l doesn't believe them]. Joe: Well, you just ( u n i n t e l l i g i b l e ) . Jane: Oh yeah [laughing]. Alan: [again looking at the thermometer and talking to himself] This is very interesting. [Jane continues to express her disb e l i e f as the; boys are thinking about the temperatures] Joe: I think the thermometer's broken. [he takes the thermometer to the water tap and places i t under running water] Hey! It's going up! [Joe then notices he had turned on the hot water. He changes i t to cold] Now i t ' l l go down. [Joe puts the thermometer back in the beaker, and he and Jane continue to discuss the data] Joe: [next reading] 40, umm, 46. Jane: 46!! 46 ehh? Joe: Put down 35 where the 20 was. Jane: Are you serious? Joe: Yes. Jane: 17 to 35? Joe: Yes! 248 Alan: It's very possible. Joe: Sort of l i k e the (??) point. Alan: It is very possible. Jane: How possible? [Jane s t i l l doesn't believe the data i s possi b l e — h e r tone continues to be one of d i s b e l i e f ] Joe: Don't put 30. Put down 25. Jane: What do you want me to put down? What was i t ? 35? Joe: [laughing] 25. Jane: [laughing] 25, you want 25? Joe: Yeah. Jane: [after a brief pause] O.K. Now what? Alan: We're s t i l l working on 20 [ i . e . , the temperature at the 20 minute mark]. Jane: Oh yeah, well. Alan: [interjecting] It's going to 60 now! Hey! It's going to 60! Shoot! It's going to 60 now. It i s 60! [Jane protests with comments such as, "get serious" a l l the time Alan i s exclaiming. Joe sticks his finger in the beaker—he doesn't believe i t ] Joe: It's hot! [shaking his hand] Jane: Well, what is i t now? Probably 80 or something. Joe: It's 58. Alan: Are you kidding? We're s t i l l working on 20 minutes. Joe: No, we're not. Alan: 22. Joe: It's longer than 20 minutes. [Jane is changing the data] I'm the monitor. Jane: Oh yeah? [laughing] Joe: O.K. It went up to, [pause] I ' l l measure i t i f you want, le t ' s say 76. [At th i s point the other students begin to complain about a l l of the changes in the data—there i s quite a bi t of background noise] Joe: There i t i s . 72. [this i s for 24 minutes] 249 Jane: [a short time later] What's the temperature now? Joe: 80. Jane: 80? 32 minutes? [ i t is actually 26 minutes, but Jane has inserted some additional times to spread out the increase] Joe: 81. No, put 80. So they continued, with the boys preferring to record the data as observed and Jane i n s i s t i n g i t was impossible. Joe pointed out that water b o i l s very quickly when i t i s heated "to make tea or coffee." The teacher soon interjected to discuss the investigation with the class. The " s c i e n t i s t s " were no longer able to discuss their results, and a l l additional readings were taken quietly. By the time the water began to b o i l , the period was nearly over. The teacher advised the students to leave the water for another two minutes because "we should have two readings the same." The students were told to complete their laboratory reports for the next day, and the investigation was discussed. During that discussion there was no suggestion that the data had been altered in any way. 

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