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Children's perceptions of gravity and motion across three tasks : a case study of six grade seven students Paras, Stephen Gerald 1990

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CHILDREN'S PERCEPTIONS OF GRAVITY AND MOTION ACROSS THREE TASKS: A CASE STUDY OF SIX GRADE SEVEN STUDENTS by STEPHEN GERALD PARAS B.Ed. The U n i v e r s i t y of B r i t i s h Columbia, 1979 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n THE FACULTY OF GRADUATE STUDIES (Department of Mathematics and Science Education) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA September 1990 (c) Stephen G e r a l d Paras, 1990 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. 1 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. Department of Mathematics and Science Education The University of British Columbia Vancouver, Canada Date September, 28, 1990  DE-6 (2/88) i i ABSTRACT The purpose of the study was to examine children's i n t u i t i v e knowledge i n the f i e l d of physical science, e l i c i t i n g t h e i r theories of gravity and motion. Six grade seven children were interviewed across three tasks using a * demonstration-interview' technique. The three tasks involved the motion of b a l l s of d i f f e r e n t mass r o l l i n g down an i n c l i n e d plane, f a l l i n g f r e e l y i n a i r , and f a l l i n g i n a w a t e r - f i l l e d tube. In each task, children were asked to predict and explain what would happen when one b a l l i s Met go', and when two b a l l s of equal s i z e but d i f f e r e n t mass were " l e t go'. They were allowed to observe the phenomenon, and explain what they observed. Also, each c h i l d was asked to predict and explain what would happen when the experiment i s done i n a hypothetical s i t u a t i o n on the moon, and i n a space c r a f t i n outer space. The results of the study confirmed the commonly held ideas children maintain of gravity and motion, and yet illuminated some new connections between gravity and other factors. Having conducted the interviews across three tasks, a r i c h amount of information was revealed, and a variety of possible structures of children's conceptual frameworks of gravity and motion was deduced. i i i The study r e v e a l e d that c h i l d r e n ' s p r i o r knowledge has an impact on the a c q u i s i t i o n of s c i e n c e concepts as taught through formal s c h o o l i n g . T h e i r ideas p e r s i s t i n s p i t e of the classroom s c h o o l i n g they r e c e i v e . T h e r e f o r e i t i s o f t e n necessary to r e s t r u c t u r e t h i s p r i o r knowledge before new knowledge can be p r o p e r l y i n c o r p o r a t e d i n t o t h e i r conceptual frameworks. The study suggests that educators, as well as c u r r i c u l u m w r i t e r s , need to re-examine the i n s t r u c t i o n a l methods and the r o l e of i n q u i r y i n s c i e n c e education. i v TABLE OP CONTENTS ABSTRACT i i LIST OF TABLES v i ACKNOWLEDGEMENTS v i i THE INTRODUCTION 1 CHAPTER I: REVIEW OF THE LITERATURE 4 CHAPTER I I : THE PROBLEM, GENERAL METHODOLOGY, AND 9 THE THREE EXPERIMENTAL TASKS 2.1 The Problem 9 2.1.1 Review of Research of Student's Ideas 9 of G r a v i t y 2.1.2 The Purpose of the Study 11 2.2 General Methodology 13 2.2.1 I n t r o d u c t i o n 13 2.2.2 P o p u l a t i o n Sample 14 2.2.3 The Interview 15 2.3 The Three Experimental Tasks 16 2.3.1 I n t r o d u c t i o n 16 2.3.2 The I n c l i n e d Plane 16 2.3.3 Free F a l l 17 2.3.4 W a t e r - f i l l e d Tubes 17 CHAPTER I I I : DATA COLLECTION AND ANALYSIS 19 3.1 Task #1: The I n c l i n e d Plane 19 3.1.1 I n t r o d u c t i o n 19 3.1.2 One B a l l on the I n c l i n e d Plane 19 3.1.3 Two B a l l s on the I n c l i n e d Plane 26 3.1.4 On the Moon 27 3.1.5 In a Space C r a f t 30 3.1.6 Summary of the Bata 32 3.2 Task #2: V e r t i c a l F r e e - f a l l 34 3.2.1 I n t r o d u c t i o n 34 3.2.2 One B a l l F a l l i n g F r e e l y i n A i r 34 3.2.3 Two B a l l s F a l l i n g F r e e l y i n A i r 41 3.2.4 On the Moon 44 3.2.5 In a Space C r a f t 46 3.2.6 Summary of the Data 47 3.3 Task #3: V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube 49 3.3.1 I n t r o d u c t i o n 49 3.3.2 One B a l l F a l l i n g i n Water 51 3.3.3 Two B a l l s F a l l i n g i n Water 56 3.3.4 On the Moon 58 3.3.5 In a Space C r a f t 60 3.3.6 Summary of the Data 61 V CHAPTER IV: DISCUSSION OF THE RESULTS 63 4.1 Task #1: The I n c l i n e d Plane 63 4.1.1 Summary of the R e s u l t s 63 4.1.1.1 One B a l l 63 4.1.1.2 Two B a l l s 63 4.1.1.3 On the Moon 63 4.1.1.4 In Space 64 4.1.2 D i s c u s s i o n of the R e s u l t s 64 4.2 Task #2: V e r t i c a l F r e e - f a l l 66 4.2.1 Summary of the R e s u l t s 66 4.2.1.1 One B a l l 66 4.2.1.2 Two B a l l s 66 4.2.1.3 On the Moon 66 4.2.1.4 In Space 67 4.2.2 D i s c u s s i o n of the R e s u l t s 67 4.3 Task #3: V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube 68 4.3.1 Summary of the R e s u l t s 68 4.3.1.1 One B a l l 68 4.3.1.2 Two B a l l s 68 4.3.1.3 On the Moon 68 4.3.1.4 In Space 79 4.3.2 D i s c u s s i o n of the R e s u l t s 70 4.4 The o r i e s of G r a v i t y 71 4.5 A comparison of the Three Tasks 73 4.6 R e v i s i o n and C o n s t r u c t i o n of Ideas 74 4.7 Bias of Observations 75 CHAPTER V: CONCLUSIONS AND IMPLICATIONS 7 6 5.1 The Three Tasks 76 5.2 I m p l i c a t i o n s f o r Teaching Science 78 REFERENCES 81 APPENDIX 1: Sample of a Complete Interview 87 T r a n s c r i p t i o n APPENDIX 2: C o r r e l a t i o n of Students' Numbers to 97 T h e i r Names v i LIST OP TABLES TABLE I Interview P r o t o c o l of Task #1 20 TABLE II Task #1: P r e d i c t i o n s of B a l l s on the 22 I n c l i n e d Plane TABLE I I I P r e d i c t i o n Summary of Task #1 23 TABLE IV Task #1: E x p l a n a t i o n s of P r e d i c t i o n s of 24 B a l l s on the I n c l i n e d Plane TABLE V Interview P r o t o c o l of Task #2 35 TABLE VI Task #2: P r e d i c t i o n s of B a l l s i n Free 36 V e r t i c a l F a l l TABLE VII P r e d i c t i o n Summary of Task #2 37 TABLE VIII Task #2: E x p l a n a t i o n of P r e d i c t i o n s of 38 B a l l s i n Free V e r t i c a l F a l l TABLE IX Interview P r o t o c o l of Task #3 50 TABLE X Task #3: P r e d i c t i o n s of V e r t i c a l F a l l i n 52 a F l u i d - f i l l e d Tube TABLE XI P r e d i c t i o n Summary of Task #3 53 TABLE XII Task #3: E x p l a n a t i o n of P r e d i c t i o n s of 54 V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube TABLE XIII Components of the The o r i e s of G r a v i t y 72 v i i ACKNOWLEDGEMENTS I would l i k e t o e x p r e s s my s i n c e r e s t a p p r e c i a t i o n t o Dr. Bob C a r l i s l e f o r t h e p e r s i s t e n t h e l p he p r o v i d e d i n o r d e r t o produce t h i s work. H i s d e d i c a t i o n t o h i s s t u d e n t s , t o h i s work, and t o knowledge have l e f t a l a s t i n g i m p r e s s i o n on my l i f e . Thank you f o r b e i n g a s o u r c e of m o t i v a t i o n ; b e l i e v i n g i n me when I d i d not b e l i e v e i n m y s e l f . I would l i k e t o thank t h e members of t h e f a c u l t y and s t a f f of t h e S c i e n c e E d u c a t i o n department f o r t a k i n g t h e time t o sh a r e t h e i r e x p e r t i s e . I would l i k e t o thank my s i x c h i l d r e n f o r g i v i n g up t h e i r daddy so t h a t he c o u l d s t u d y . I would l i k e t o g i v e s p e c i a l thanks t o my b e s t f r i e n d , my w i f e , Glenda. Her w i l l i n g n e s s t o s u p p o r t me i n t h i s endeavor has been t h e d r i v i n g f o r c e b e h i n d the c o m p l e t i o n of t h i s t a s k . F o r her hours of t y p i n g and e d i t i n g t h a t were so f r e e l y g i v e n when she d i d n ' t have any, thank you. Her su p p o r t has been i n s t r u m e n t a l i n s e e i n g t h i s dream come t r u e . 1 INTRODUCTION Science education i s fundamental to the process of advancing the development of s c i e n c e - r e l a t e d f i e l d s . We l i v e i n an era where the r a p i d advances of s c i e n t i f i c and t e c h n o l o g i c a l i n n o v a t i o n are making u n r e l e n t i n g demands on s c i e n c e e d u c a t i o n . T h i s has s e t the stage f o r s c i e n c e educators to re-examine t h e i r p h i l o s o p h i e s and approaches towards edu c a t i o n . In p a r t , s c i e n c e education i n v o l v e s the teacher, the student, and the s u b j e c t matter. The s u b j e c t matter being taught i n the l a s t decade has been s t a t i c i n comparison to the changing r o l e of the teacher and the student. With the onset of Sputnik being launched i n t o space, Canada and the U n i t e d S t a t e s implemented new i n s t r u c t i o n a l methods f o r t e a c h i n g s c i e n c e . The r o l e of the t e a c h e r and the r o l e of the student, both underwent r e v i s i o n . ^Hands-on' a c t i v i t i e s , experimentation, and i n v e s t i g a t i o n , became new buzz words amongst the s c i e n c e educators. Rather than students being p a s s i v e i n t h e i r r o l e , they became a c t i v e p a r t i c i p a n t s engaged i n the l e a r n i n g of s c i e n c e . In the face of s c i e n t i f i c advancement, the trends i n s c i e n c e education are undergoing constant change. Concepts of the student's r o l e i n the l e a r n i n g process has changed r e f l e c t i n g the p h i l o s o p h i c a l stance of the time. And 2 because s c i e n c e e d u c a t i o n i s a f i e l d t h a t has t i e s w i t h b o t h s c i e n c e and e d u c a t i o n , i t r e f l e c t s t h e i d e a s of b o t h s c i e n c e and p s y c h o l o g y . From t h e i n f l u e n c e of B a c o n i a n e m p i r i c a l - i n d u c t i v i s m , s c i e n c e was seen as p r o d u c i n g a b s o l u t e l y t r u e d i s c o v e r i e s by p e o p l e who r e c o r d e d o b s e r v a t i o n s w i t h o u t any form of b i a s . However, t h i s p h i l o s o p h y i s p r e s e n t l y b e i n g c h a l l e n g e d as r e s e a r c h i n d i c a t e s t h a t o b s e r v a t i o n i s i n f l u e n c e d by p r e e x i s t e n t t h e o r y (Chalmers, 1978). The new t r e n d i n s c i e n c e e d u c a t i o n r e s e a r c h i n c o r p o r a t e s the c o n t r i b u t i o n s of c o g n i t i v e s c i e n t i s t s , s p e c i a l i s t s i n the t r a d i t i o n a l s c i e n c e d i s c i p l i n e s , s c i e n c e e d u c a t o r s , and many o t h e r p r o f e s s i o n a l s from r e l a t e d d i s c i p l i n e s . As a r e s u l t of i n t e r d i s c i p l i n a r y work s e v e r a l r e s e a r c h themes have r e s u l t e d , and amongst them i s a growing consensus about the n a t u r e of t h e l e a r n e r ( L i n n , 1987). "Jean Peaget's c l a s s i c s t u d i e s of c h i l d r e n ' s c o n c e p t i o n s of t h e w o r l d have i n f l u e n c e d e d u c a t o r s t o r e s p e c t the l e a r n e r as one who a c t i v e l y c o n s t r u c t s a coh e r e n t w o r l d view and who seeks p e r s i s t e n t l y t o i n t e g r a t e f o r m a l and i n f o r m a l l e a r n i n g e x p e r i e n c e s . ( L i n n , 1987, p. 195) S t u d e n t s , much l i k e s c i e n t i s t s , b r i n g w i t h them a w e a l t h of i n t u i t i v e knowledge t h a t they w i l l use t o e x p l a i n t h e w o r l d t h a t they e x p e r i e n c e . T h e i r n a t u r a l c u r i o s i t y d r i v e s them t o i n q u i r e about phenomena t h a t they e n c o u n t e r , and i n t h e i r q uest t o u n d e r s t a n d and e x p l a i n , they experiment and t h e o r i z e . They c o n s t r u c t meaning from t h e e x p e r i e n c e s t h a t 3 they e n c o u n t e r , f o r m i n g a framework of i n t u i t i v e knowledge l o n g b e f o r e f o r m a l e d u c a t i o n ever b e g i n s . T h i s s t u d y e x p l o r e s what i n t u i t i v e knowledge s t u d e n t s b r i n g w i t h them t o a s p e c i f i c s c i e n t i f i c phenomena, and observes how s t u d e n t s r e v i s e o r c o n s t r u c t new t h e o r i e s upon i n t e r a c t i o n w i t h t h e phenomena. The s t u d y w i l l f o c u s on c h i l d r e n ' s i n t u i t i v e t h e o r i e s of g r a v i t y and m o t i o n a c r o s s t h r e e e x p e r i m e n t a l t a s k s . 4 CHAPTER I REVIEW OF THE LITERATURE I n q u i r y i s a t t h e h e a r t of s c i e n c e e d u c a t i o n . S c i e n c e e d u c a t i o n i n c l u d e s i n q u i r y as a n e c e s s a r y component f o r e f f e c t i v e l e a r n i n g because t h i s form of l e a r n i n g c l o s e l y p a r a l l e l s t h e t y p e of s c i e n c e l e a r n i n g t h a t would n a t u r a l l y t a k e p l a c e i n t h e w o r l d o u t s i d e of t h e c l a s s r o o m . However, the f i e l d of i n q u i r y c o v e r s a broad scope of d e f i n i t i o n and a p p l i c a t i o n w i t h l i t t l e agreement as t o i t s aims and methods. Our p r e s e n t knowledge of c o g n i t i v e p r o c e s s e s remains f r a g m e n t a r y . K a r m i l o f f - S m i t h and I n h e l d e r (1976) sought t o d i s c o v e r t h e i n t e r p l a y between a c t i o n sequences and c h i l d r e n ' s " t h e o r i e s - i n - a c t i o n " i n the n a t u r a l e x p l o r a t i o n of c h i l d r e n . Of t h e many d i s c o v e r i e s they made, i t was observ e d " t h a t c h i l d r e n h o l d on t o t h e i r i n i t i a l t h e o r y f o r as l o n g as they can. Even when they f i n a l l y do ta k e counter-examples i n t o c o n s i d e r a t i o n , they f i r s t p r e f e r t o c r e a t e a new t h e o r y , q u i t e independent of t h e f i r s t one, b e f o r e f i n a l l y a t t e m p t i n g t o u n i f y a l l ev e n t s under a s i n g l e , b r o a d e r t h e o r y . " The c h i l d ' s i n t u i t i v e t h e o r y seems t o g u i d e what he sees and does. C h i l d r e n d e v e l o p i d e a s and t h e o r i e s about the n a t u r a l w o r l d l o n g b e f o r e t h e i r f o r m a l s c h o o l i n g b e g i n s . These views and i d e a s a r e f i r m l y h e l d and r e s i s t r e v i s i o n d e s p i t e f o r m a l s c h o o l i n g . Preece (1984) s t a t e d t h a t " C h i l d r e n ' s 5 i n t u i t i v e views have been found t o be remarkably r e s i s t a n t t o change, even i n t h e f a c e of c o n t r a r y s c i e n c e t e a c h i n g . " Ausubel (1968) r e s e a r c h e d t h e d e t r i m e n t a l e f f e c t s t h a t t h e s e i n t u i t i v e views had on t h e a c q u i s i t i o n of new c o n c e p t u a l knowledge. He c o n c l u d e d t h a t "the u n l e a r n i n g of p r e c o n c e p t i o n s might v e r y w e l l prove t o be t h e most d e t e r m i n a t i v e s i n g l e f a c t o r i n t h e a c q u i s i t i o n and r e t e n t i o n of s u b j e c t - m a t t e r s t r u c t u r e . " F u r t h e r m o r e , r e s e a r c h has found t h a t sometimes when l e a r n i n g s c i e n c e a t s c h o o l , p u p i l s make i n a p p r o p r i a t e l i n k s t o t h e i r p r i o r knowledge, and hence the meaning they c o n s t r u c t a r e not t h o s e i n t e n d e d by the t e a c h e r ( B e l l 1985, T a s k e r 1981). C o n s t r u c t i v i s m e n c a p s u l a t e s the n o t i o n t h a t i n d i v i d u a l s t r y t o g i v e meaning t o t h e events and i d e a s w h i c h they e x p e r i e n c e . T h i s approach t o l e a r n i n g has i t s r o o t s i n the V e r s t e h e n t r a d i t i o n . I t i s " r e l a t i v i s t i n o u t l o o k , showing the i n f l u e n c e of p o s t - i n d u c t i v i s t views of knowledge, w i t h a b e l i e f i n t h e v a l u e of an h o l i s t i c approach t o phenomena, s e e k i n g t o p e r c e i v e u n d e r s t a n d i n g " ( G i l b e r t and Watts, 1983). T h i s approach i s a l s o e v i d e n t i n q u a l i t a t i v e r e s e a r c h approaches such as ethnography, case s t u d y , and p a r t i c i p a n t o b s e r v a t i o n (Magoon 1977). The p e r s o n a l c o n s t r u c t p s y c h o l o g y of K e l l y (1955) has r e c e n t l y been r e l a t e d t o s c i e n c e e d u c a t i o n and i s r e c e i v i n g c a r e f u l c o n s i d e r a t i o n (Pope and G i l b e r t , 1983). 6 Other r e c e n t r e s e a r c h by C l a x t o n (1983) d e s c r i b e s the way i n whi c h c h i l d r e n d e v e l o p t h e i r own t h e o r i e s and p e r s o n a l c o n s t r u c t s based on d i r e c t e x p e r i e n c e w i t h t h e p h y s i c a l w o r l d , and i n f o r m a l s o c i a l i n t e r a c t i o n s . L i k e a d u l t s c i e n t i s t s , they seek t o c o n s t r u c t t h e o r i e s t o e x p l a i n what th e y e x p e r i e n c e . The b r a i n i s not a p a s s i v e consumer of i n f o r m a t i o n . I n s t e a d i t a c t i v e l y c o n s t r u c t s i t s own i n t e r p r e t a t i o n s of i n f o r m a t i o n , and draws i n f e r e n c e s from them. The b r a i n i g n o r e s some i n f o r m a t i o n and s e l e c t i v e l y a t t e n d s t o o t h e r i n f o r m a t i o n ... much more th a n a "blank s l a t e ' t h a t p a s s i v e l y l e a r n s and r e c o r d s i n c oming i n f o r m a t i o n . (Osborne and W i t t r o c k , 1983) The magnitude of the impact of c h i l d r e n ' s t h e o r i e s on the a c q u i s i t i o n of new co n c e p t s can not be u n d e r e s t i m a t e d . M i l l a r and D r i v e r (1987) c l a i m t h a t b o t h c h i l d r e n ' s o b s e r v a t i o n s and t h e i r p r o c e s s of e x p e r i m e n t a t i o n , depends on t h e l e a r n e r ' s p r i o r knowledge. Hodson (1986) says " I f we ac c e p t t h a t p r i o r knowledge d e t e r m i n e s the o b s e r v a t i o n s we can make and t h e i n t e r p r e t a t i o n s we a r e c a p a b l e o f , then i t f o l l o w s t h a t we need t o t a k e much more account than p r e v i o u s l y of c h i l d r e n ' s own views of the w o r l d . " M a r c i a L i n n (1987) c o n f i r m s t h i s by s t a t i n g , " I t appears t h a t s t u d e n t s c o n s t a n t l y i n t e r p r e t new i n f o r m a t i o n based on t h e i r p a r t i c u l a r w o r l d view. These f i n d i n g s emphasize t h e imp o r t a n c e of i d e n t i f y i n g and a r t i c u l a t i n g t h e l e a r n e r ' s i d e a s and t h i n k i n g s k i l l s w i t h i n a s u b j e c t m a t t e r domain as a b a s i s f o r d e s i g n i n g i n s t r u c t i o n . " 7 R e a l i z i n g the i m p o r t a n c e of i n t u i t i v e knowledge on the a c q u i s i t i o n of new knowledge, s t u d i e s have been conducted t o examine s t u d e n t s ' s c i e n t i f i c i d e a s on such t o p i c s as heat ( E r i c k s o n , 1979), k i n e m a t i c s (Trowbridge and McDermott, 1981), l i g h t ( R i c e and Feher, 1987), g r a v i t y (Noce, T o r o s a n t u c c i , & V i c e n t i n i , 1988), th e e a r t h , m a t t e r , e l e c t r i c i t y , and dynamics ( D r i v e r , Guesne, & T i b e r g h i e n , 1985). These s t u d i e s have shown t h a t c h i l d r e n from a v e r y e a r l y age c o n s t r u c t v a r i e d and complex c o n c e p t u a l s t r u c t u r e s t h a t r e f l e c t a c o h e r e n t u n d e r s t a n d i n g of t h e i r w o r l d . There a r e some g e n e r a l i t i e s t o t h e i r t h e o r i e s , and a c c o r d i n g t o D r i v e r , Guesne, and T i b e r g h i e n (1985), t h e s e i d e a s a r e p e r s o n a l , even though they may s i m i l a r t o o t h e r s ' i d e a s ; they may seem i n c o h e r e n t , as the c r i t e r i a f o r coherence as p e r c e i v e d by a s t u d e n t a r e not t h e same as t h o s e of a s c i e n t i s t ; and they a r e s t a b l e . In o r d e r t o e f f e c t i v e l y r e a l i z e t h e l e a r n i n g of s c i e n c e , i t i s i m p e r a t i v e t h a t t h e l e a r n i n g s i t u a t i o n promote c o n c e p t u a l change, a c c e p t i n g t h a t c h i l d r e n p e r s i s t i n k e e p i n g t h e i r i n t u i t i v e i d e a s . P e t e r Hewson (1980) s t a t e s , " I t i s w i d e l y a c c e p t e d t h a t a person's e x i s t i n g knowledge p l a y s a c r i t i c a l r o l e i n l e a r n i n g s c i e n c e . These c o n c e p t i o n s p l a y an i m p o r t a n t r o l e even though they a r e o f t e n i m p l i c i t , w i t h the p e r s o n h o l d i n g them u n a b l e t o a r t i c u l a t e them i n any d e t a i l and c o n s t i t u t e an u n i d e n t i f i e d b a r r i e r t o g r e a t e r u n d e r s t a n d i n g of some t o p i c or o t h e r . " S t u d i e s of 8 s t u d e n t s ' i d e a s about g r a v i t y , f a l l i n g o b j e c t s , and p r o j e c t i l e s have a l s o i n d i c a t e d t h a t t h e same n a i v e t h e o r i e s t e n d t o be used by i n d i v i d u a l s and t h a t t h e s e t h e o r i e s p e r s i s t d e s p i t e f o r m a l i n s t r u c t i o n i n p h y s i c s even up t o c o l l e g e l e v e l (Caramazza, McCloskey, and Green, 1981). These c o n c e p t i o n s sometimes r e f l e c t i d e a s which have been h e l d by s c i e n t i s t s i n t h e p a s t , and as Caramazza e t . a l . (1981) s u g g e s t , "they a r e a n a t u r a l outcome of e x p e r i e n c e w i t h t h e w o r l d . " The development of t h e s e i d e a s a r e l o g i c a l and f o l l o w a p r o g r e s s i o n s i m i l a r t o h i s t o r i c a l development of the same i d e a s . A r e c e n t a r t i c l e by Clough and D r i v e r (1986) e n t i t l e d , "Use of S t u d e n t s ' C o n c e p t u a l Frameworks A c r o s s D i f f e r e n t Task C o n t e x t s " p r o v i d e s a work s i m i l a r t o t h e s t u d y . The purpose of t h e s t u d y was not o n l y t o document s t u d e n t s ' i d e a s or c o n c e p t u a l frameworks, but t o i n v e s t i g a t e t h e c o n s i s t e n c y w i t h which th e i d e a s were used by i n d i v i d u a l s i n d i f f e r e n t c o n t e x t s . T h e i r f i n d i n g s i n d i c a t e d t h a t "when t a s k s p r o b i n g t h e same s c i e n t i f i c i d e a s a r e p e r c e i v e d d i f f e r e n t l y by s t u d e n t s , and seem not t o address t h e same phenomenon, no c o n s i s t e n c y of response a c r o s s c o n t e x t s i s a p p a r e n t . " 9 CHAPTER I I THE PROBLEM, GENERAL METHODOLOGY, AND THE THREE EXPERIMENTAL TASKS 2.1 The Problem 2.1.1 Review o f R e s e a r c h of S t u d e n t s ' Ideas of G r a v i t y I n t e r a c t i o n between " p r i o r - k n o w l e d g e " and fo r m a l i n s t r u c t i o n i s more pronounced i n t h e s t u d y of mechanics than f o r o t h e r s c i e n c e s u b j e c t s a c c o r d i n g t o Champagne, K l o p f e r and Gunstone (1981). I n t e r e s t i n g l y enough, r e s e a r c h by Helm (1978, 1980) i n d i c a t e s t h a t t e a c h e r s as w e l l as s t u d e n t s m a i n t a i n i n c o r r e c t c o n c e p t u a l frameworks i n t h e f i e l d of mechanics. I t may be because of t h i s t h a t t h e co n c e p t s i n th e f i e l d of p h y s i c s have r e c e i v e d such a c o n s i d e r a b l e amount of a t t e n t i o n . F u r t h e r m o r e , s t u d y i n the f i e l d of mechanics seems t o demand t h e a t t e n t i o n of e d u c a t i o n a l r e s e a r c h e r s because of the h i n d r a n c e t o concept development t h a t m i s c o n c e p t i o n s cause. A i e l 1 o - N i c o s i a and Sperandeo-Mineo (1980) s t a t e , " M i s c o n c e p t i o n s can have a " n e g a t i v e ' e f f e c t : t h e s t u d e n t s draw " m i s l e a d i n g i n f o r m a t i o n ' from common e x p e r i e n c e and then g e n e r a l i z e i t u s i n g "wrong c o n n e c t i o n s ' . " 10 R e s e a r c h on c h i l d r e n ' s t h e o r i e s of g r a v i t y was conducted on I t a l i a n m i d d l e s c h o o l c h i l d r e n (Noce, T o r o s a n t u c c e , & V i c e n t i n i , 1988) r e v e a l i n g t h a t t h e r e a r e f o u r commonly h e l d schema of g r a v i t y . In the f i r s t c a t e g o r y , the f o r c e of g r a v i t y causes o b j e c t s t o f a l l . G r a v i t y makes o b j e c t s have w e i g h t , and c o n s e q u e n t l y they f a l l . The second c a t e g o r y i d e n t i f i e s t h a t o b j e c t s f a l l e i t h e r because of g r a v i t y , or because of w e i g h t . In b o t h of t h e s e c a t e g o r i e s , a i r i s a n e c e s s a r y i n g r e d i e n t f o r the f o r c e of g r a v i t y t o a c t . In t h e t h i r d c a t e g o r y , f r e e - f a l l i s thought of as a n a t u r a l m o t i o n independent of weight or g r a v i t y . The f o u r t h c a t e g o r y i s Newtonian, where g r a v i t y i s on the e a r t h or moon, and a c t s r e g a r d l e s s of t h e p r e s ence of a i r or n o t . There a r e some g e n e r a l i t i e s t h a t a r e common t o t h e schema t h a t c h i l d r e n p r e s e n t when they d i s c u s s g r a v i t y . R e s e a r c h conducted by Watts and G i l b e r t (1983) and M o o r f o o t (1983) have i n d i c a t e d a c l o s e c o n n e c t i o n between g r a v i t y and the atmosphere. R a r e l y i s g r a v i t y p e r c e i v e d t o e x i s t on t h e moon, i n space, o r i n water. S t e a d and Osborne (1980) show t h a t g r a v i t y i s seen t o o p e r a t e d i f f e r e n t l y i n d i f f e r e n t c i r c u m s t a n c e s : i t i n c r e a s e s w i t h h e i g h t ( D r i v e r , 1983); i t makes h e a v i e r o b j e c t s f a l l f a s t e r (Watts, 1982; Gunstone and W h i t e , 1980); and i t a c t s d i f f e r e n t l y on d i f f e r e n t o b j e c t s ( S t e a d and Osborne, 1980; W a t t s , 1982). 11 A n o t h e r main f e a t u r e of s t u d i e s i n g r a v i t y shows t h a t g r a v i t y i s s o l e l y r e l a t e d t o f a l l i n g o b j e c t s (Watts and Z y l b e r s z t a j n , 1981). 2.1.2 The Purpose of t h e Study T h i s s t u d y examines s e v e n t h grade s t u d e n t s ' i n t u i t i v e knowledge of g r a v i t y and motio n . G r a v i t y b e i n g an a b s t r a c t e n t i t y , l e n d s i t s e l f t o a wide v a r i e t y of t h e o r i e s , and c o n s e q u e n t l y t h e r e a r e many s t r o n g l y h e l d m i s c o n c e p t i o n s of the n a t u r e of g r a v i t y and motion. R e s e a r c h b e i n g conducted on g r a v i t y t o d a t e , seeks t o e l i c i t r e sponses as t o t h e c o n d i t i o n s n e c e s s a r y f o r g r a v i t y t o e x i s t ; where g r a v i t y i s found, and the n a t u r e of the c i r c u m s t a n c e s t h a t c h i l d r e n a t t r i b u t e t o the f o r c e of g r a v i t y . Most r e s e a r c h has s t u d i e d t h e s e c o n c e p t s of g r a v i t y when i n v e s t i g a t i n g o b j e c t s i n v e r t i c a l f r e e - f a l l . T h i s s t u d y c o n t i n u e s t h i s l i n e of i n v e s t i g a t i o n but i s unique i n t h a t i t e l i c i t s c h i l d r e n ' s i d e a s of t h e mo t i o n of o b j e c t s a c r o s s two o t h e r t a s k s as w e l l : r o l l i n g down an i n c l i n e d p l a n e , and f a l l i n g i n water. A good comparison of the responses of t h e same c h i l d r e n t o t h e s e two o t h e r t a s k s w i l l be h e l p f u l i n v e r i f y i n g t h a t g r a v i t y i s s o l e l y r e l a t e d t o f a l l i n g o b j e c t s . F u r t h e r m o r e , t h i s r e s e a r c h endeavors t o expand the c o n c e p t u a l framework of e x i s t e n t t h e o r i e s of g r a v i t y , a dding more d e t a i l t o p a s t r e s e a r c h . 12 D u r i n g t h e c o u r s e of t h e i n t e r v i e w , t h e s t u d e n t s w i l l have o p p o r t u n i t y t o r e v i s e or r e c o n s t r u c t t h e i r t h e o r i e s . The e x t e n t of e v i d e n c e of any c h i l d r e n u n d e r g o i n g c o n c e p t u a l change d u r i n g t h e c h i l d r e n ' s e x p e r i e n c e of t h e t h r e e t a s k s , w i l l g i v e some i n d i c a t i o n of how s t r o n g l y t h e i r i d e a s a r e m a i n t a i n e d . Such e v i d e n c e w i l l s u p p o r t t h e i d e a t h a t c h i l d r e n ' s t h e o r i e s a r e p e r s i s t e n t i n s p i t e of what they e x p e r i e n c e . R e s e a r c h c l a i m s t h a t p r i o r knowledge a f f e c t s one's a b i l i t y t o make u n b i a s e d o b s e r v a t i o n . E v i d e n c e f o r a b i a s of o b s e r v a t i o n ( c o n s i s t e n t w i t h t h e i r p r e d i c t i o n s ) w i l l be examined. In summary, t h e s t u d y r e s e a r c h e s t h e f o l l o w i n g q u e s t i o n s : 1. What a r e s e v e n t h grade s t u d e n t s ' i n t u i t i v e t h e o r i e s of g r a v i t y and mo t i o n a c r o s s t h r e e t a s k s ? 1.1 What a r e the p r e d i c t i o n s of how g r a v i t y a f f e c t s t h e motion of b a l l s i n each c o n t e x t ? 1.2 What a r e t h e p r e d i c t i o n s of how g r a v i t y a f f e c t s t h e m o t i o n of b a l l s of d i f f e r i n g mass i n each c o n t e x t , and on t h e moon, and i n space? 1.3 What a r e t h e i r e x p l a n a t i o n s f o r each p r e d i c t i o n ? 2. Do s e v e n t h grade s t u d e n t s m a i n t a i n a c o n s i s t e n t t h e o r y of g r a v i t y and mo t i o n a c r o s s t h e t h r e e t a s k s ? 13 3. Do s e v e n t h grade s t u d e n t s ' i n t u i t i v e t h e o r i e s of g r a v i t y and m o t i o n undergo r e v i s i o n when f a c e d w i t h e x p e r i m e n t a l o b s e r v a t i o n of the phenomena? 4. Do s e v e n t h grade s t u d e n t s see what they p r e d i c t t h e y w i l l s ee, r e g a r d l e s s of what a c t u a l l y happens? 2 .2 General Methodology 2 . 2 . 1 introduction A v a r i e t y of methods have been d e v e l o p e d f o r e l i c i t i n g c h i l d r e n ' s i d e a s about s c i e n c e . White (1979) a n a l y z e d the s i m i l a r i t i e s and d i f f e r e n c e s of some of t h e s e methods. However, most methods do i n v o l v e i n - d e p t h i n t e r v i e w s w i t h c h i l d r e n ( P i n e s e t . a l . , 1978; Brumby, 1979; T i b e r g h i e n , 1980). Some common methods of i n t e r v i e w a r e t h e " i n t e r v i e w -a b o u t - i n s t a n c e s ' (Osborne & G i l b e r t , 1980; G i l b e r t , W a t t s , & Osborne, 1981) used t o e x p l o r e c h i l d r e n ' s meanings f o r many words; t h e s i n t e r v i e w about e v e n t s ' (Osborne, 1980; Cosgrove & Osborne, 1981; S c h o l i u m , 1981; and Happs, 1981) used t o e s t a b l i s h a c h i l d ' s view of t h e w o r l d ; the i n v e s t i g a t i o n i n t e r v i e w , i n which c h i l d r e n p a r t i c i p a t e i n a t a s k as a means t o e l i c i t t h e i r i d e a s (Champagne, K l o p f e r , & Anderson, 1980); and the d e m o n s t r a t i o n i n t e r v i e w , i n which the i n t e r v i e w demonstrates a t a s k t o e l i c i t t h e i r i d e a s . 14 As a means t o e l i c i t t h e s t u d e n t s ' c o n c e p t i o n s of g r a v i t y and m o t i o n i n t h i s r e s e a r c h , a f l e x i b l e " d e m o n s t r a t i o n i n t e r v i e w ' was c a r r i e d out w i t h t h e s t u d e n t s . These t y p e s of i n t e r v i e w s a r e w e l l e s t a b l i s h e d methodology i n t h e f i e l d of c o g n i t i v e r e s e a r c h ( G o l d b e r g and McDermott, 1983). Each s t u d e n t ' s c o n c e p t i o n of the phenomenon was e l i c i t e d by a s k i n g p r e d i c t i o n s and e x p l a n a t i o n s of t h e t a s k a t hand. I n t e r v i e w s a r e v a l u a b l e i n t h a t they a l l o w f o r c l a r i f i c a t i o n of q u e s t i o n s and r e s p o n s e s , and a l l o w f o r p r o b i n g of d e t a i l s i n o r d e r t h a t a c o n c e p t u a l framework c o u l d be r e c o n s t r u c t e d by t h e r e s e a r c h e r . The development f o r i n t e r v i e w i n g proceeded p r o g r e s s i v e l y ; a t r i a l p r o t o c o l was d e v e l o p e d and p i l o t e d . H aving e v a l u a t e d t h e i n t e r v i e w and i t s t e c h n i q u e , a f i n a l p r o t o c o l f o r i n t e r v i e w was used. T h i s p r o t o c o l remained f l e x i b l e , dependent upon the responses g i v e n by the s t u d e n t s ; where c l a r i f i c a t i o n was needed or more p r o b i n g p o s s i b l e , t h e i n t e r v i e w e r c o n t i n u e d q u e s t i o n i n g . 2.2.2 P o p u l a t i o n Sample S c i e n c e assessment of s t u d e n t s i n B r i t i s h Columbia o c c u r s a t grades f o u r , s e v e n , and t e n . For ease of o b t a i n i n g m a t e r i a l s and making g e n e r a l a p p l i c a t i o n s , t h e s t u d y was conducted a t one of. t h e s e l e v e l s , t h a t b e i n g grade seven. F u r t h e r m o r e , l i t t l e d i f f e r e n c e of i n t u i t i v e knowledge i s 1 5 e x p e c t e d from t h i r d grade t o s e v e n t h grade, and s e v e n t h grade marks t h e t r a n s i t i o n from el e m e n t a r y t o sec o n d a r y s c h o o l . The sample p o p u l a t i o n i s composed of s i x s t u d e n t s , t h r e e male and t h r e e female. S t u d e n t s chosen were tho s e of average, t o above-average performance i n s c i e n c e as de t e r m i n e d by p a s t r e p o r t c a r d grades i n c o n j u n c t i o n w i t h s i m i l a r s t a n d i n g on t h e i r Canadian Achievement T e s t s c o r e s . The s t u d e n t s chosen a l l a t t e n d e d the same s c h o o l , a p r i v a t e s c h o o l i n t h e lower m a i n l a n d of B r i t i s h Columbia. 2.2.3 The I n t e r v i e w The i n t e r v i e w a c r o s s each t a s k f o l l o w e d t h e same g e n e r a l format. The i n t e r v i e w e r p r e s e n t e d a t a s k and asked f o r a p r e d i c t i o n t o t h e outcome of t h e t a s k . F o l l o w i n g the p r e d i c t i o n of t h e outcome, the i n t e r v i e w e r i n v i t e d an e x p l a n a t i o n of t h e p r e d i c t i o n . The s t u d e n t s were then g i v e n the o p p o r t u n i t y t o observe the phenomenon. Having ob s e r v e d t h e outcome, t h e s t u d e n t s were g i v e n f u r t h e r o p p o r t u n i t y t o e x p l a i n what they observed. At the end of each e x p e r i m e n t a l t a s k t h e s t u d e n t summarized h i s knowledge by w r i t i n g down h i s / h e r i d e a s on an i n t e r v i e w c a r d . Having completed a l l t h e e x p e r i m e n t a l t a s k s , t h e s t u d e n t s were g i v e n o p p o r t u n i t y t o read t h e i r i d e a s , and make any changes t o t h e i d e a s p r e s e n t e d on t h e c a r d s . 16 A f i n a l i n t e r v i e w w i t h the s t u d e n t s was used t o g i v e them an o p p o r t u n i t y t o l o o k a t a l l t h e i r c o n c l u d i n g remarks t h a t were w r i t t e n on t h e i n t e r v i e w c a r d s . Having read them, they were a l l o w e d t o make any changes they wished. F u r t h e r q u e s t i o n s were asked t o e x p l o r e any t h e o r i e s not y e t exha u s t e d p r e v i o u s l y by t h e t h r e e t a s k s . 2.3 The Three E x p e r i m e n t a l Tasks 2.3.1 I n t r o d u c t i o n The f o l l o w i n g t h r e e t a s k s were a d m i n i s t e r e d t o t h e s t u d e n t s d u r i n g t h e c o u r s e of the i n t e r v i e w s . Each t a s k i n v o l v e d t h e m o t i o n of b a l l s of d i f f e r e n t mass, due t o the i n f l u e n c e of g r a v i t y . In each t a s k , the format f o r i n t e r v i e w i n g was the same. The s t u d e n t s were g i v e n an o p p o r t u n i t y t o examine t h e two b a l l s of d i f f e r e n t mass, make a p r e d i c t i o n f o r t h e outcome of r e l e a s i n g one of t h e b a l l s , make a p r e d i c t i o n f o r the outcome of r e l e a s i n g two b a l l s a t the same t i m e , and then o b s e rve t h e phenomenon and e x p l a i n . 2.3.2 The I n c l i n e d P l a n e The f i r s t experiment i n v o l v e d the motion of one, and then two b a l l s of d i f f e r e n t mass r o l l i n g down an i n c l i n e d p l a n e . The s i t u a t i o n p r e s e n t e d i s common t o a c h i l d ' s everyday 17 e x p e r i e n c e which w i l l have p r o v i d e d ample o p p o r t u n i t y f o r a development of- p r i o r knowledge. C o n s e q u e n t l y , i t was e x p e c t e d t h a t the s t u d e n t s would c o r r e c t l y p r e d i c t t h e outcome. The o b s e r v a b l e e v i d e n c e p r o v i d e d i n t h i s t a s k c o u l d i n c r e a s e t h e l i k e l i h o o d f o r a wrong p r e d i c t i o n i n the second t a s k s h o u l d t h e s t u d e n t ' s c o n c e p t i o n of mo t i o n on an i n c l i n e d p l a n e be p a r t of t h e same scheme as f r e e v e r t i c a l f a l l . 2.3.3 F r e e - f a l l The second experiment i n v o l v e d t h e r e l e a s e of one, and then two b a l l s , v e r t i c a l l y , i n a i r . The s e t - u p was s i m p l e . One b a l l was r e l e a s e d by hand over t h e t a b l e . Then t h e two b a l l s of d i f f e r e n t mass (8 gm, and 80 gm) were loa d e d i n t o an e l e c t r i c a l l y o p e r a t e d b a l 1 - d r o p p i n g mechanism, and r e l e a s e d a t the same time from a two meter h e i g h t . The two b a l l s of d i f f e r e n t mass dropped a t t h e same speed. 2.3.4 W a t e r - f i l l e d Tubes The t h i r d experiment i n v o l v e d t h e r e l e a s e of one, and then two b a l l s , v e r t i c a l l y , over two w a t e r - f i l l e d t u b e s . U n l i k e the p r e v i o u s s i t u a t i o n , which a l s o i n v o l v e d v e r t i c a l f a l l , the i n c r e a s e d buoyancy due t o the water does e f f e c t the r a t e of f a l l . T h i s s i t u a t i o n i s common t o most c h i l d r e n , s i n c e t hey swim i n water, o r watch o b j e c t s f l o a t i n water. Y e t , 18 s i n c e many t h e o r i e s of g r a v i t y a r e dependant upon the pr e s e n c e of a i r , t h i s c o u l d p r o v i d e an i n c o n s i s t e n c y t o t h e scheme. As su c h , would t h e i n c o n s i s t e n c y be d e t e c t e d by the s t u d e n t and pose a r e a s o n f o r r e s t r u c t u r i n g knowledge, or i s the s i t u a t i o n seen as b e i n g d i f f e r e n t , and the i n c o n s i s t e n c y i g n o r e d ? 19 CHAPTER I I I DATA COLLECTION AND ANALYSIS 3.1 Task #1: The I n c l i n e d P l a n e 3.1.1 I n t r o d u c t i o n The i n t e r v i e w e r i n t r o d u c e d t h e n a t u r e of t h e i n t e r v i e w p r o c e d u r e by e x p l a i n i n g t h a t i t would t a k e p l a c e i n t h r e e s e c t i o n s . Between each s e c t i o n , t h e s t u d e n t was a l l o w e d t o ta k e a break i f he/she chose t o do so. The i n t e r v i e w e r mentioned t h a t he was not l o o k i n g f o r r i g h t o r wrong answers, but f o r the s t u d e n t ' s own i d e a s . The i n t e r v i e w p r o t o c o l f o r t a s k #1 i s shown i n T a b l e I . 3.1.2 pne B a l l on the Inclined Plane The i n t e r v i e w e r handed two b a l l s t o the s t u d e n t , one metal and one wood. (The metal b a l l ' s weight i s 80 grams, w h i l e t h e g r e e n wooden b a l l ' s weight i s 8 grams.) Each s t u d e n t was asked t o examine t h e b a l l s and t o " t e l l me what you can about t h e s e b a l l s . " I n v a r i a b l y , one of the f i r s t comments made mentioned t h e d i f f e r e n c e of t h e i r w e i g h t s . C o l o r , n a t u r e of m a t e r i a l s , and s i z e were a l s o r e f e r r e d t o . 20 TABLE I Interview P r o t o c o l of Task #1 Part 1: One B a l l a. OBSERVATION Have the student examine the two b a l l s . * What can you t e l l me about these two b a l l s ? b. PREDICTION: Hol d i n g one b a l l at the top of the i n c l i n e d plane, ask: * What w i l l happen i f I l e t go of t h i s b a l l ? c. EXPLANATION: Before l e t t i n g go of the b a l l , ask: * Why do you t h i n k that w i l l happen? Having l e t go of the b a l l , i n v i t e a d i s c u s s i o n on the nature of g r a v i t y i n t h i s s e t t i n g . * How does the i n c l i n e d plane a f f e c t the motion of the b a l l ? P a r t 2: Two B a l l s a. PREDICTION: Hol d i n g the two b a l l s at the top of the i n c l i n e d plane, ask: * What w i l l happen i f I l e t go of both of these b a l l s at the same time? b. EXPLANATION: Before l e t t i n g go of the b a l l s , ask: * Why do you t h i n k that w i l l happen? c. EXPERIMENTATION: The i n t e r v i e w e r takes the two b a l l s and conducts the experiment. d. OBSERVE & EXPLAIN: Have the student d e s c r i b e what he saw happen. Have the student o f f e r an e x p l a n a t i o n f o r what he saw happen. e. HYPOTHETICAL SITUATION In order t o tease out f u r t h e r i n t u i t i v e knowledge that students possess of g r a v i t y and motion, the s u b j e c t i s asked: * What would happen i f I were to do t h i s experiment on the moon? F u r t h e r the d i s c u s s i o n by s e t t i n g the context of the experiment to take p l a c e on a space c r a f t i n outer space, and ask t h i s q u e s t i o n : * What would happen i f I were to do t h i s experiment on a space c r a f t i n outer space? f . CONCLUDING REMARKS Have the s u b j e c t s o f f e r any general t h e o r i e s on the nature of g r a v i t y , and i t s a f f e c t s on the motion of o b j e c t s of d i f f e r e n t mass bu a s k i n g : * What do you know now about the way o b j e c t s r o l l down an i n c l i n e d plane? Have the s u b j e c t s w r i t e down t h e i r ideas on a c a r d . 21 When t h e i n t e r v i e w e r p i c k e d up t h e metal b a l l and p l a c e d i t on t o p of t h e "ramp* and asked, "What w i l l happen i f I l e t go of t h i s b a l l ? " , a l l the s t u d e n t s mentioned i t would "go down" o r " r o l l down." T a b l e I I c o n t a i n s a l i s t of the p r e d i c t i o n s of the s t u d e n t s . T a b l e I I I l i s t s summarized s t u d e n t p r e d i c t i o n s . T a b l e IV shows t h e s t u d e n t s ' answers when asked, "Why do you t h i n k t h a t w i l l happen?" When asked, "Why do you t h i n k t h a t w i l l happen?", two of t h e s t u d e n t s r e f e r r e d t o g r a v i t y , one of t h e s t u d e n t s mentioned " t h e weight of t h e b a l l pushes i t " , two of them mentioned "because i t ' s heavy", and one s t u d e n t s a i d "because i t ' s d o w n h i l l " . I t i s i n t e r e s t i n g t o n o t e t h a t o n l y two of t h e s t u d e n t s mentioned g r a v i t y as the cause f o r t h e b a l l r o l l i n g down the ramp. Perhaps g r a v i t y i s not n e c e s s a r i l y p a r t of c h i l d r e n ' s schema i n t h i s c o n t e x t , but i s more o f t e n p a r t of t h e schema f o r f r e e - f a l l i n g o b j e c t s . L o o k i n g a t t h e e x p l a n a t i o n s i n the second t a s k w i l l c o n f i r m i f t h i s i s so. Weight i s a l s o seen as an a l t e r n a t i v e c a u s a t i v e agent f o r t h e f o r c e b e h i n d o b j e c t s moving down (Noce, T o r o s a n t u c c i , & V i c e n t i n i , 1988). T h i s i d e a was mentioned by one of t h e s t u d e n t s who s a i d , " t h e weight of t h e b a l l pushes i t . " T h i s statement does g i v e an i n d i c a t i o n of an o u t s i d e f o r c e a c t i n g upon t h e b a l l . The two s t u d e n t s who mentioned t h a t i t r o l l s down because " i t ' s heavy", may be u s i n g t h e same concept as w e i g h t . TABLE I I Task #1: P r e d i c t i o n s of B a l l s on t h e I n c l i n e d P i LETTING GO OP ONE BALL Student # P r e d i c t i o n s 1 I t would r o l l down. 2 I t would r o l l down t o t h e o t h e r end. 3 I t would go t o the end. 4 I t w i l l go down. 5 I t would go down. 6 I t would go down. LETTING GO OF BOTH BALLS AT THE SAME TIME Student # P r e d i c t i o n s 1 The l i g h t e r b a l l r o l l s s l o w e r . 2 They would r o l l down the same. 3 The h e a v i e r b a l l would go f a s t e r . 4 The h e a v i e r b a l l would go f a s t e r . 5 The h e a v i e r b a l l would do down f a s t e r . 6 The h e a v i e r b a l l would go down f a s t e r . LETTING GO OF BOTH BALLS ON THE MOON Student # P r e d i c t i o n s 1 Same as E a r t h but s l o w e r . 2 They wouldn't go anywhere. 3 They wouldn't go anywhere. 4 They would j u s t s t a y t h e r e 5 They would f l o a t . 6 They would p r o b a b l y j u s t s t a y t h e r e . LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # P r e d i c t i o n s 1 They would f l o a t . 2 They wouldn't go anywhere. 3 They would f l o a t . 4 They would s t a y t h e r e . 5 They would f l o a t . 6 They would f l o a t around. TABLE I I I P r e d i c t i o n Summary of Task #1 Student # Name 1 John 2 Roy 3 P e t e r 4 Karen 5 Mary 6 L i n d a 1 B a l l r o l l r o l l r o l l r o l l r o l l r o l l 2 B a l l s h e a v i e r f a s t e r b o t h same h e a v i e r f a s t e r h e a v i e r f a s t e r h e a v i e r f a s t e r h e a v i e r f a s t e r On t h e Moon h e a v i e r f a s t e r f l o a t f l o a t f l o a t f l o a t f l o a t In Space * f f l o a t f l o a t f l o a t f l o a t f l o a t f l o a t M a t e r i n t h e i n t e r v e i w the p r e d i c t i o n changed t o say the h e a v i e r b a l l would r o l l f a s t e r . 24 TABLE IV Task #1: E x p l a n a t i o n s of P r e d i c t i o n s of B a l l s on the I n c l i n e d Plane LETTING GO OF ONE BALL Student # E x p l a n a t i o n s 1 I t would r o l l down because g r a v i t y would push i t down. 2 I t would r o l l down to the other end because g r a v i t y i s p u l l i n g i t down. 3 I t would go to the end because the weight of the b a l l pushes i t . 4 I t w i l l go down because i t s heavy and because i t ' s on a s l a n t . 5 I t would go down because i t heavy. 6 I t would go down because i t s d o w n h i l l . LETTING GO OF BOTH BALLS AT THE SAME TIME Student # E x p l a n a t i o n s 1 The l i g h t e r b a l l r o l l s slower because not as much weight on the ramp pushes down. 2 They would r o l l down the same. 3 The h e a v i e r b a l l would go f a s t e r because i t ' s h e a v i e r . 4 The h e a v i e r b a l l would go f a s t e r because i t ' s h e a v i e r . 5 The h e a v i e r b a l l would go down f a s t e r because i t p i c k s up more speed than the l i g h t e r b a l l . 6 The h e a v i e r b a l l would go down f a s t e r because i t ' s h e a v i e r . LETTING GO OF BOTH BALLS ON THE MOON Student # E x p l a n a t i o n s 1 Same as E a r t h but slower because there i s l e s s g r a v i t y . 2 , They wouldn't go anywhere because there i s no g r a v i t y . 3 They wouldn't go anywhere because g r a v i t y would stop i t ; g r a v i t y would keep i t up. G r a v i t y on the moon keeps o b j e c t s f l o a t i n g i n space. 4 They would j u s t s t a y there because there i s no g r a v i t y on the moon. 5 They would f l o a t because the a i r i s d i f f e r e n t . 6 They would probably j u s t s t a y there because something must be wrong; probably d i f f e r e n t a i r , atmosphere or s t u f f . 25 LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # E x p l a n a t i o n s 1 They would f l o a t because there i s no g r a v i t y i n outer space. 2 They wouldn't go anywhere because there i s no g r a v i t y i n outer space. 3 They would f l o a t because when you're i n outer space there i s the same g r a v i t y as when you are on the moon. 4 They would s t a y there because i n outer space there i s no g r a v i t y . 5 They would f l o a t because the a i r i s the same i n s i d e as o u t s i d e the space c r a f t . 6 They would f l o a t around because I heard t h a t when you go up there you s t a r t f l o a t i n g around. 26 But because they do not refer to a force, but rather to a property of the object i t s e l f (heaviness), perhaps they see motion as something that an object does rather than something that i s done to an object. 3.1.3 Two B a l l s on the Inclined Plane When the interviewer posed the question "What w i l l happen i f I l e t go of these b a l l s at the same time?" f i v e of the six students predicted that the heavier b a l l would r o l l down faster, while one student said, "They would r o l l down the same." Because students play with b a l l s , r o l l them on the road, and have ample opportunity for observing b a l l s of di f f e r e n t mass i n motion, i t was expected that a l l the predictions would indicate the heavier one would r o l l f a ster. The student who predicted otherwise, Roy, did not offer an explanation for his prediction. The explanations for the "heavier b a l l r o l l i n g faster' are prescribed as three types. Roy mentioned "the l i g h t e r b a l l r o l l s slower because not as much weight on the ramp pushes down". "Why weight would increase the speed' i s not mentioned i n the explanation even though weight i s d e f i n i t e l y connected to the difference i n speed. Three students mentioned "because i t s heavier" as an explanation for difference i n the speed. Again, how heaviness i s 27 to i n c r e a s e d speed i n t h e i r concept of motion i s not evident by t h e i r e x p l a n a t i o n . Mary mentioned "The h e a v i e r b a l l would go down f a s t e r because i t p i c k s up more speed than the l i g h t e r b a l l . " T h i s student o f f e r s a more d e t a i l e d e x p l a n a t i o n l i n k i n g the i d e a of "heaviness* to " i n c r e a s e d speed' by mentioning that "the b a l l p i c k s up speed". T h i s e x p l a n a t i o n c o u l d be i n t e r p r e t e d as r e f e r r i n g to " i n c r e a s e d momentum due to the d i f f e r e n c e mass* as the reason f o r i t going f a s t e r . 3.1 . 4 On the Moon The i n t e r v i e w e r then posed a h y p o t h e t i c a l s i t u a t i o n to the student by asking "What would happen i f I were to do t h i s experiment on the moon?" Three c a t e g o r i e s of response were i d e n t i f i e d . Only one student, John, thought that there was any g r a v i t y on the moon. As much of the l i t e r a t u r e has i n d i c a t e d , most students do not p e r c e i v e there to be g r a v i t y on the moon. His p r e d i c t i o n of what would happen was "same as E a r t h but slower". Four of the students p r e d i c t e d that the b a l l s "wouldn't go anywhere" or " j u s t s t a y t h e r e " . One student, Mary, claimed that "they would f l o a t " . T h i s f i v e t o one r a t i o of students p e r c e i v i n g that there i s no g r a v i t y on the moon confirms the commonly h e l d t h e o r i e s r e p o r t e d i n l i t e r a t u r e (Noce e t . a l . , 1988; Watts & Z y l b e r s z t a j n , 1981; 28 Watts & G i l b e r t , 1983; Moorfoot, 1983; Stead & Osborne, 1980). E x p l a n a t i o n s f o r t h e i r p r e d i c t i o n s o f f e r e d a great deal of i n s i g h t i n t o t h e i r schema of g r a v i t y , r e v e a l i n g a great deal of v a r i a t i o n i n conceptual frameworks. The student who s a i d that the b a l l s would go slower, John, e x p l a i n e d that there i s l e s s g r a v i t y on the moon. At f i r s t i t seems evident that t h i s student has a Newtonian scheme of g r a v i t y where s m a l l e r o b j e c t s p u l l with l e s s a t t r a c t i o n . A c c o r d i n g to Noce e t . a l . (1988), t h i s type of scheme i s very i n f r e q u e n t . Two stu d e n t s ' e x p l a n a t i o n s r e f l e c t e d the common n o t i o n that there i s no g r a v i t y on the moon without any apparent suggestions f o r why that might be so. One student's e x p l a n a t i o n , Mary's, was "the a i r i s d i f f e r e n t " . I t i s i n t e r e s t i n g to note that i n t h i s case, g r a v i t y was not the " f i r s t - mentioned' reason, but r a t h e r , the a i r . T h i s student has ap p a r e n t l y connected "no g r a v i t y on the moon' to "the a i r being d i f f e r e n t ' and chose to e x p l a i n her ideas without even r e f e r r i n g to g r a v i t y at a l l . Again, t h i s confirms what has been r e p o r t e d i n l i t e r a t u r e where the concepts of the atmosphere and g r a v i t y are c l o s e l y r e l a t e d . Unique i n the e x p l a n a t i o n i s a l s o the f a c t that Mary d i d not say that there was no " a i r ' or "atmosphere', but claimed i n s t e a d that "the a i r i s d i f f e r e n t " . Such a 29 s t a tement would i n d i c a t e t h a t t h i s p e r s o n b e l i e v e s t h a t t h e r e i s a i r on t h e moon. P e t e r , who s a i d "they ( t h e b a l l s ) wouldn't go anywhere" e x p l a i n e d , " G r a v i t y would s t o p i t . G r a v i t y on the moon keeps o b j e c t s f l o a t i n g i n s p a c e . " T h i s s t u d e n t seems t o m a i n t a i n a " g e o c e n t r i c ' view of g r a v i t y . The g r a v i t y from t h e E a r t h reaches a l l t h e way t o t h e moon, " s t o p p i n g i t " , and k e e p i n g t h e o b j e c t a f l o a t . I n f e r r e d from t h e phrase " s t o p p i n g i t " i s t h e i d e a t h a t t h e g r a v i t y on t h e moon a c t u a l l y s t o p s t h e b a l l from f a l l i n g . I f t h i s be t h e c o r r e c t i n t e r p r e t a t i o n of the p h r a s e , then g r a v i t y on t h e moon i s seen as i n t e r f e r i n g w i t h t h e "normal c o u r s e of m o t i o n ' which i s " t o f a l l ' r e g a r d l e s s of t h e pr e s e n c e of g r a v i t y . Then g r a v i t y on t h e moon f u n c t i o n s so as t o m a i n t a i n an e q u i l i b r i u m so t h a t o b j e c t s w i l l f l o a t . A g a i n , t h i s scheme of g r a v i t y i s r e p o r t e d by Noce e t . a l . (1988) where " f r e e f a l l ' i s thought of as a n a t u r a l m o t i o n , and g r a v i t y a c t s t o m a i n t a i n an e q u i l i b r i u m c a u s i n g o b j e c t s t o f l o a t . One o t h e r s t u d e n t , L i n d a , e x p l a i n e d "something must be wrong; p r o b a b l y d i f f e r e n t a i r , atmosphere o r s t u f f . " Once a g a i n t h e r e i s t h e c l o s e c o n n e c t i o n between "the atmosphere' or t h e " a i r ' , and " g r a v i t y ' . However, her statement "something must be wrong" i n d i c a t e s a n o t i o n of t h e r e b e i n g a p r o p e r s t a t e of s e t of c o n d i t i o n s . I t seems t h a t whatever 30 doesn't p a r a l l e l t h e c o n d i t i o n s found on E a r t h would s e r v e no u s e f u l f u n c t i o n f o r mankind, and t h e r e f o r e "something must be wrong". T h i s t y p e of schema i s a " s e l f - c e n t e r e d ' and "human-centered' v i e w p o i n t , common among young c h i l d r e n , i n t e r p r e t i n g and c o n s i d e r i n g t h i n g s i n terms of human e x p e r i e n c e s and commonly h e l d v a l u e s ( G i l b e r t , Osborne, & Fensham, 1982). 3.1.5 I n a Space C r a f t The i n t e r v i e w e r completed t h e f i r s t t a s k by p o s i n g t h i s h y p o t h e t i c a l s i t u a t i o n : "What would happen i f I were t o do t h i s experiment on a space c r a f t i n o u t e r s p a c e ? " By p o s i n g t h i s c o n t e x t u a l s i t u a t i o n , one c o u l d p o s s i b l y c l a r i f y t he r e a s o n f o r t h e absence of g r a v i t y by comparing s i t u a t i o n s on the moon w i t h space. I n i t i a l l y , a l l s i x s t u d e n t s p r e d i c t e d t h a t t h e b a l l s would f l o a t i n the space c r a f t . However, John, who c l a i m e d t h a t t h e r e would be g r a v i t y on t h e moon, changed h i s p r e d i c t i o n as he de v e l o p e d a new t h e o r y d u r i n g t h e c o u r s e of the i n t e r v i e w . H i s f i n a l p r e d i c t i o n was t h a t t h e h e a v i e r b a l l would r o l l down t h e ramp f a s t e r on a space c r a f t l i k e i t does on E a r t h . H i s e x p l a n a t i o n f o r the space c r a f t h a v i n g g r a v i t y l i k e on E a r t h was t h a t " the space c r a f t i s an e n c l o s e d s p a c e . " I n e n c l o s e d spaces t h e r e i s g r e a t e r g r a v i t y . The moon i s an open space. The E a r t h i s an e n c l o s e d space because i t has an atmosphere around i t . The c o m p l e x i t y of such a scheme i s 31 the space c r a f t , t h e s t u d e n t responded by s a y i n g t h a t because i t wasn't an e n c l o s e d space, t h e b a l l s would f l o a t . The o t h e r f i v e s t u d e n t reasoned t h a t t h e b a l l s would f l o a t i n t h e space c r a f t y i e l d i n g t h r e e c a t e g o r i e s of e x p l a n a t i o n s . Two of t h e f i v e s t u d e n t s s a i d t h a t t h e r e was no g r a v i t y i n o u t e r space. No o t h e r e x p l a n a t i o n was g i v e n by them. One s t u d e n t , P e t e r , s a i d "When you're i n o u t e r space t h e r e i s t h e same g r a v i t y as when you a r e on t h e moon." T h i s s t u d e n t m a i n t a i n e d a c o n s i s t e n t g e o c e n t r i c scheme of g r a v i t y as e x p l a i n e d f o r t h e moon. Mary, who d i d not r e f e r t o a l a c k of g r a v i t y f o r her e x p l a n a t i o n of o b j e c t s f l o a t i n g on t h e moon c l a i m e d " t h e a i r i s t h e same i n s i d e as o u t s i d e t h e space c r a f t " a g a i n f a i l i n g t o mention g r a v i t y . I n t h i s s e e m i n g l y p a r a l l e l c o n t e x t , Mary has o f f e r e d a c o n s i s t e n t e x p l a n a t i o n w i t h t h e p r e v i o u s one. L i n d a e x p l a i n e d " I he a r d t h a t when you go up t h e r e you s t a r t f l o a t i n g around." Her response i n t h i s case seems t o i n d i c a t e t h a t " o u t e r space' was a c o n t e x t t h a t was not i n c l u d e d i n her c o n c e p t u a l framework. F o r t h i s r e a s o n , she r e f l e c t s on what she has h e a r d , and not what she t h e o r i z e s . F u r t h e r p r o b i n g d u r i n g t h e c o u r s e of t h e i n t e r v i e w i l l u m i n a t e s t h i s i d e a . 32 3.1.6 Summary of t h e Data Even though g r a v i t y was not mentioned by f o u r of t h e s t u d e n t s as an e x p l a n a t i o n f o r b a l l s r o l l i n g down a ramp, by the time the i n t e r v i e w f o l l o w i n g t h e f i r s t t a s k was completed, i t was e v i d e n t t h a t g r a v i t y was seen as b e i n g a t l e a s t p a r t l y r e s p o n s i b l e f o r the m o t i o n , e s p e c i a l l y s i n c e b a l l s f l o a t on t h e moon. F i v e of t h e s i x s t u d e n t s p r e d i c t e d t h a t t h e h e a v i e r b a l l r o l l s f a s t e r down a ramp t h a n a l i g h t e r b a l l . The h i g h p e r c e n t a g e of s t u d e n t s making a " c o r r e c t ' p r e d i c t i o n i n d i c a t e s t h a t c h i l d r e n a r e f a m i l i a r w i t h t h i s c o n t e x t . However, a c o r r e c t p r e d i c t i o n does not n e c e s s a r i l y i n d i c a t e t h a t t h e c o n c e p t u a l framework t h a t they used t o make t h e p r e d i c t i o n be c o r r e c t . Three c a t e g o r i e s of responses were i d e n t i f i e d f o r e x p l a n a t i o n s of t h e t a s k . One mentioned "weight', and t h r e e mentioned " h e a v i n e s s ' as reasons f o r t h e h e a v i e r b a l l r o l l i n g f a s t e r . I t i s not c l e a r i f weight and h e a v i n e s s a r e synonymous. Yet i t i s e v i d e n t t h a t weight and / o r h e a v i n e s s a r e c l o s e l y r e l a t e d t o the r a t e of mo t i o n on an i n c l i n e d p l a n e . One s t u d e n t , Mary, o f f e r e d an e x p l a n a t i o n t h a t resembles momentum. 33 By h y p o t h e s i z i n g that the same experiment be done on the moon, the i n t e r v i e w e r was able to e l i c i t ideas as to "where* and "why' there i s g r a v i t y . One student, John, e x p l a i n e d t h a t there i s l e s s g r a v i t y on the moon, a Newtonian concept of g r a v i t y . One student, Peter, b e l i e v e d that moon's g r a v i t y p u l l e d the op p o s i t e d i r e c t i o n making o b j e c t s f l o a t on the moon - a g e o c e n t r i c concept of g r a v i t y . Four students f e l t t h a t t h e r e was no g r a v i t y on the moon. Of the fo u r , two made mention of the a i r as being r e s p o n s i b l e f o r the o b j e c t s f l o a t i n g r a t h e r than f a l l i n g . By posing the h y p o t h e t i c a l s i t u a t i o n of a space c r a f t , one co u l d deduce i f the students' t h e o r i e s were connected to "land mass'. E v i d e n t l y , "land mass' was not a p a r t of t h e i r schema f o r the presence of g r a v i t y . However, one student, John, d i d c o n s t r u c t a new i d e a , s a y i n g that i n an "enclosed space' such as the space c r a f t , normal g r a v i t y would occur. G r a v i t y i s seen as a f o r c e that f u n c t i o n s on the E a r t h . Because i t serves no u s e f u l f u n c t i o n elsewhere, i t does not e x i s t on the moon or i n space. I t s presence i s c l o s e l y r e l a t e d to the a i r , or some substance i n the a i r . On the ramp, g r a v i t y p u l l s h e a v i e r o b j e c t s f a s t e r than l i g h t e r ones. 34 3.2 TA.SK #2: V e r t i c a l Free F a l l 3.2.1 I n t r o d u c t i o n When s t u d y i n g c h i l d r e n ' s concepts of g r a v i t y , perhaps the most common task employed i n v o l v e s o b s e r v a t i o n of o b j e c t s i n f r e e v e r t i c a l f a l l . In common to other r e s e a r c h , was the use of p r e d i c t i n g the outcome of the same experiment on the moon and/or i n outer space. By h y p o t h e s i z i n g the outcomes of the tasks i n these c o n t e x t s , the schema of g r a v i t y across d i f f e r e n t s i t u a t i o n a l contexts would be e l i c i t e d . The i n t e r v i e w which f o l l o w s was r i c h i n data. The i n t e r v i e w p r o t o c o l f o r task #2 i s shown i n Table V. 3.2.2 One B a l l F a l l i n g F r e e l y i n A i r The i n t e r v i e w e r used the same two b a l l s as i n the previous task. H o l d i n g the metal b a l l i n a dropping p o s i t i o n about a h a l f a meter above the desk, the i n t e r v i e w e r asked, "What w i l l happen i f I l e t go of t h i s b a l l ? " F i v e students s a i d " i t would f a l l " , and one s a i d " i t would drop". Table VI c o n t a i n s a l i s t of the p r e d i c t i o n s of the students. Table VII l i s t s summarized student p r e d i c t i o n s . Table VIII shows the s t u d e n t s ' answers when asked, "Why do you t h i n k that w i l l happen?" 35 TABLE V Interview P r o t o c o l of Task #2 Part 1: One B a l l a. OBSERVATION: Have a student examine the two b a l l s to see t h a t they are the same two b a l l s . b. PREDICTION: Hol d i n g one b a l l i n a dropping p o s i t i o n , ask: * What w i l l happen i f I l e t go of t h i s b a l l ? c. EXPLANATION: Before l e t t i n g go of the b a l l , ask: * Why do you t h i n k t h a t w i l l happen? Having l e t go of the b a l l i n v i t e a d i s c u s s i o n on the nature of g r a v i t y . P a r t 2: Two B a l l s a. PREDICTION: Hol d i n g the two b a l l s i n a dropping p o s i t i o n , ask: * What w i l l happen i f I l e t go of both of these b a l l s at the same time? b. EXPLANATION: Before l e t t i n g go of the b a l l s , ask: * Why do you t h i n k that w i l l happen? c. EXPERIMENTATION: The i n t e r v i e w e r w i l l take the two b a l l s and conduct the experiment u s i n g the e l e c t r i c b a l l dropper. d. OBSERVE & EXPLAIN: Have the student d e s c r i b e what he saw happen. Have the student o f f e r an e x p l a n a t i o n f o r what he saw happen. e. HYPOTHETICAL SITUATION In order t o tease out f u r t h e r i n t u i t i v e knowledge that students possess of g r a v i t y and motion, the s u b j e c t i s asked: * What would happen i f I were to do t h i s experiment on the moon? (probe f o r t h e o r i e s of the c o n d i t i o n s necessary f o r g r a v i t y to take p l a c e . ) F u r t h e r the d i s c u s s i o n by s e t t i n g the context of the experiment t o take p l a c e on a space c r a f t i n outer space, and ask t h i s q u e s t i o n : * What would happen i f I were to do t h i s experiment i n a s p a c e - c r a f t i n outer space? f. CONCLUDING REMARKS Have the s u b j e c t s o f f e r any general t h e o r i e s on the nature of g r a v i t y , and i t s a f f e c t s on the motion of o b j e c t s of d i f f e r e n t mass by asking; * What do you know now about the way o b j e c t s f a l l ? Have the s u b j e c t s w r i t e down t h e i r ideas or t h e o r i e s on an i n t e r v i e w card. TABLE VI Task #2: P r e d i c t i o n s of B a l l s i n Free V e r t i c a l F a l LETTING GO OF ONE BALL Student # P r e d i c t i o n s 1 I t would f a l l . 2 I t would f a l l . 3 I t would f a l l . 4 I t would f a l l . 5 I t would f a l l . 6 I t w i l l drop. LETTING GO OF BOTH BALLS AT THE SAME TIME Student # P r e d i c t i o n s 1 They would f a l l at the same speed. 2 They would f a l l at the same time. 3 The h e a v i e r b a l l would f a l l f a s t e r . 4 The h e a v i e r b a l l would f a l l f a s t e r . 5 They would go down at the same speed. 6 The h e a v i e r b a l l would f a l l f a s t e r . LETTING GO OF BOTH BALLS ON THE MOON Student # P r e d i c t i o n s 1 The h e a v i e r o b j e c t would f a l l f a s t e r . 2 They wouldn't go anywhere. 3 They would j u s t say t h e r e . 4 They would s t a y i n the box. 5 They would f l o a t . 6 They would f l o a t . LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # P r e d i c t i o n s 1 They would f a l l at the same speed. 2 They wouldn't go anywhere. 3 They would j u s t s t a y t h e r e . 4 They would j u s t s t a y i n the box. 5 They would f l o a t . 6 They would f l o a t around. 37 TABLE VII P r e d i c t i o n Summary of Task #2 Student # 1 B a l l 2 B a l l s On the In Moon Space 1 f a l l same h e a v i e r same speed f a s t e r speed 2 f a l l same f l o a t f l o a t speed 3 f a l l h e a v i e r f l o a t f l o a t f a s t e r 4 f a l l h e a v i e r f l o a t f l o a t f a s t e r 5 f a l l same f l o a t f l o a t speed 6 f a l l h e a v i e r f l o a t f l o a t f a s t e r 38 TABLE VI I I Task #2: E x p l a n a t i o n s of Free V e r t i c a l P r e d i c t i o n s F a l l of B a l l s i n LETTING GO OF ONE BALL Student # 1 2 3 4 5 Ex p l a n a t i o n s would would would would would E a r t h . I t w i l l drop because i t s heavy and i t moves down. It I t I t I t I t f a l l f a l l f a l l f a l l f a l l because because because because because of g r a v i t y , of g r a v i t y , g r a v i t y p u l l s i t . g r a v i t y p u l l s i t down, i t can't f l o a t on the Student # 1 4 5 LETTING GO OF BOTH BALLS AT THE SAME TIME Ex p l a n a t i o n s They would f a l l at the same speed because there i s g r a v i t y and i t doesn't r e a l l y matter how heavy one t h i n g i s . They would f a l l at the same time because the p u l l of g r a v i t y i s the same. I t i s no d i f f e r e n t on any b a l l . The h e a v i e r b a l l would f a l l f a s t e r because i t s h e a v i e r , or i t has more weight. G r a v i t y might p u l l the h e a v i e r b a l l s t r o n g e r . The h e a v i e r b a l l would f a l l f a s t e r because i t ' s h e a v i e r . They would go down at the same speed because when they go down the ramp they have a s l o p e to p i c k up speed, but when they are dropping they don't have time to p i c k up speed. The h e a v i e r one would drop f a s t e r because on the ramp t h i s one dropped f a s t e r ; because i t s h e a v i e r . LETTING GO OF BOTH BALLS ON THE MOON Student # E x p l a n a t i o n s 1 The h e a v i e r o b j e c t would f a l l f a s t e r because there i s l e s s g r a v i t y there so the h e a v i e r o b j e c t would j u s t n a t u r a l l y f a l l f a s t e r than the l i g h t o b j e c t . 2 They wouldn't go anywhere because there i s no g r a v i t y . 3 They would j u s t s t a y there because g r a v i t y keeps i t up i n the a i r . 39 4 They would stay i n the box because there i s no g r a v i t y on the moon. 5 They would f l o a t because the a i r i s d i f f e r e n t . 6 They would f l o a t because i t s something i n the a i r t h a t makes e v e r y t h i n g do i t . LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # E x p l a n a t i o n s 1 They would f a l l at the same speed because i t i s k i n d of the same as e a r t h , i t i s an enclosed space. 2 They wouldn't go anywhere because t h e r e i s no g r a v i t y . 3 They would j u s t s t a y there because g r a v i t y keeps them up., 4 They would s t a y i n the box because t h e r e i s no g r a v i t y i n outer space. 5 They would f l o a t because the a i r i s the same i n s i d e the space s h i p as o u t s i d e the s h i p . 6 They would f l o a t around because the a i r i s d i f f e r e n t . v 40 When asked, "Why do you t h i n k that w i l l happen?" the responses were more v a r i e d . Four of the students r e f e r r e d to g r a v i t y as f o r c e " p u l l i n g i t down'. It i s i n t e r e s t i n g to note that i n t h i s context, four r e f e r r e d to g r a v i t y as compared to two i n the previous task. Perhaps the most common context of the " f o r c e of g r a v i t y ' i n a c t i o n , i s "objects i n f r e e f a l l ' . The r e s e a r c h e r expected to get t h i s type of response to t h i s q u e s t i o n . I t c o u l d be that other s i t u a t i o n s (other than o b j e c t s i n f r e e - f a l l ) i n v o l v e other f o r c e s such as weight, e t c . One student, Mary, responded by s a y i n g " I t would f a l l because i t can't f l o a t on the E a r t h " . Her e x p l a n a t i o n doesn't o f f e r a reason, but claims that the e x c e p t i o n to the r u l e , on E a r t h , can't happen., T h i s response r e v e a l s her c o n c e p t i o n t h a t the n a t u r a l s t a t e of motion f o r a l l o b j e c t s on the E a r t h i s a " f a l l i n g ' motion. Li n d a responded by s a y i n g " i t s heavy and i t moves down". T h i s student p e r s o n i f i e s the a c t i o n of the b a l l as a p r o p e r t y of i t s e l f , where i t s own heaviness determines that i t w i l l move down. Again, g r a v i t y i s not mentioned. I am sure that Linda had been taught about g r a v i t y on numerous o c c a s i o n s , but yet i n t h i s c l a s s i c example of g r a v i t y , her c o n c e p t i o n does not even warrant the mentioning of i t . I t i s very p o s s i b l e t h a t the "teacher taught' concept of g r a v i t y was never accepted i n t o Linda's schema of f o r c e s and 41 motion. T h e r e f o r e , even though g r a v i t y i s a word i n c l u d e d i n her vocabulary, i t i s not used to e x p l a i n events that occur i n "every day* l i f e . 3.2.3 Two B a l l s F a l l i n g F r e e l y i n A i r The students were then posed with the q u e s t i o n , "What w i l l happen i f I l e t go of both of these b a l l s at e x a c t l y the same time?" Three of the students responded that they would f a l l at d i f f e r e n t "speeds" or "time". The other three students responded by s a y i n g that they would f a l l at the same "speed" or "time". When the i n t e r v i e w e r asked, "Why do you t h i n k that w i l l happen?", a l l the students who b e l i e v e d that they would f a l l at d i f f e r e n t speeds e x p l a i n e d "because i t ' s h e a v i e r " . No mention was made to g r a v i t y at a l l . I t seems evident from the unanimity of the response that t h e i r schema of reasoning i n f e r s " g r a v i t y * as the cause of o b j e c t s f a l l i n g , but "heaviness' as another f a c t o r t h a t i s r e s p o n s i b l e f o r i n f l u e n c i n g t h e i r r a t e of f a l l . No mechanism e x p l a i n i n g the c o n n e c t i o n i n v o l v i n g g r a v i t y , heaviness, and r a t e of f a l l , i s mentioned by the students. Of the students who p r e d i c t e d that the two b a l l s of d i f f e r e n t mass would f a l l at the same time, a l l three of t h e i r e x p l a n a t i o n s were d i f f e r e n t . John s a i d "because there 42 i s g r a v i t y , i t doesn't r e a l l y matter how heavy one t h i n g i s . " T h i s was s i m i l a r to Roy who s a i d "the p u l l of g r a v i t y i s the same. It i s no d i f f e r e n t on any b a l l . " Both students r e f e r to g r a v i t y as the reason. Roy's e x p l a n a t i o n i n c l u d e s the mechanism f o r the happening, s a y i n g that the p u l l of g r a v i t y i s the same. The t h i r d student, Mary, made r e f e r e n c e to her response i n task #1 e x p l a i n i n g that "when they go down the ramp, they have a s l o p e to p i c k up speed, but when they are dropping, they don't have time to p i c k up speed." The d i f f e r e n c e i n r a t e s of f a l l i s being a t t r i b u t e d to the presence of a s l o p e . Without the s l o p e they don't have "time" (or perhaps the necessary c o n d i t i o n s ) to p i c k up speed. G r a v i t y i s not mentioned at a l l , nor i s the cause f o r them t r a v e l l i n g at i d e n t i c a l speeds. The students were then shown an e l e c t r i c a l l y operated mechanical b a l 1 - d r o p p i n g d e v i c e . The c o n s t r u c t i o n of the d e v i c e as p e r t a i n i n g to i t s o p e r a t i o n , was e x p l a i n e d by the i n t e r v i e w e r . I t was demonstrated i n order to show that the mechanism employed, would indeed r e l e a s e both b a l l s at e x a c t l y the same time. The students were asked to stand back so that they c o u l d get a good view of the two b a l l s i n motion. A sheet of aluminum metal was p l a c e d at the bottom of the dropping s i t e , and the students i n s t r u c t e d to l i s t e n to the sound made as each f e l l , so that they c o u l d determine 43 determine by both s i g h t and sound i f the two b a l l s f e l l at d i f f e r e n t or equal r a t e s . The i n t e r v i e w e r loaded the d e v i c e with the two b a l l s , p o s i t i o n e d the b a l l dropper approximately two meters from o f f the ground, and on the count of three, t r i g g e r e d the r e l e a s e of the b a l l s . In every case, the i n t e r v i e w e r asked i f the student would l i k e the experiment repeated (even more than once i f requested) so that they would be sure of what they observed. Observations that students make can be, and o f t e n are, i n f l u e n c e d by the b e l i e f s they h o l d ( D r i v e r , Guesne, & T i b e r g h i e n , 1985). As r e s e a r c h has i n d i c a t e d , o b s e r v a t i o n i s o f t e n t h e o r y - l a d e n . The three students who p r e d i c t e d that the b a l l s would f a l l at d i f f e r e n t r a t e s c o n f i d e n t l y d e c l a r e d upon o b s e r v a t i o n of the experiment, that they, i n deed, d i d f a l l at d i f f e r e n t r a t e s . Of course, the three students who p r e d i c t e d that the two b a l l s would f a l l at the same speed, a l s o j u s t as c o n f i d e n t l y d e c l a r e d , that they observed the two b a l l s f a l l i n g at the same r a t e . Observing the a c t i o n more than once, l i s t e n i n g to the sound as the b a l l s f e l l , and observing v i s u a l l y the happening, was not enough evidence f o r f i f t y percent of the students to observe c o r r e c t l y what a c t u a l l y d i d happen. The c o n f i d e n c e with which they v e r b a l i z e d t h e i r o b s e r v a t i o n s l e d the r e s e a r c h e r to check the video tape i n slow motion to v e r i f y i f what they observed a c t u a l l y d i d occur. T h e i r o b s e r v a t i o n s were not confirmed. T h i s shows the extent to which o b s e r v a t i o n s 44 do r e f l e c t our b e l i e f systems. T h i s has some very important i m p l i c a t i o n s f o r the use of s c i e n t i f i c o b s e r v a t i o n s as a t o o l f o r i n v o k i n g conceptual change. 3.2.4 On the Moon The i n t e r v i e w e r then asked the student to p r e d i c t "What would happen i f I were to do t h i s experiment on the moon?" Two c a t e g o r i e s of p r e d i c t i o n s were i d e n t i f i e d . F i v e students p r e d i c t e d that they would " j u s t s tay t h e r e " or "would f l o a t " . The other student, John, p r e d i c t e d " t h a t the h e a v i e r o b j e c t would f a l l f a s t e r . " Of i n t e r e s t i s the f a c t t h a t John had a l s o p r e d i c t e d that on E a r t h , the two b a l l s would f a l l at e x a c t l y the same speed. T h i s apparent change i n t h e o r i e s a c r o s s "what s c i e n t i s t would deem as s i m i l a r events' r e f l e c t s how "context o r i e n t e d ' c h i l d r e n ' s t h e o r i e s r e a l l y are. Such d i s c r e p a n c i e s , when f u r t h e r i n v e s t i g a t e d , r e v e a l the complexity of c h i l d r e n ' s conceptual frameworks. When the i n t e r v i e w e r asked "Why do you t h i n k that w i l l happen?" (on the moon), two c a t e g o r i e s of response were made; those making r e f e r e n c e to a i r , and those making r e f e r e n c e to g r a v i t y . Three students made r e f e r e n c e to a i r , one c l a i m i n g "the a i r i s d i f f e r e n t " , and one e x p l a i n i n g "because i t s something i n the a i r that makes e v e r y t h i n g do i t . " I t seems t h a t c h i l d r e n do b e l i e v e that a i r e x i s t s on the moon. In a g e n e r a t i o n where c h i l d r e n have the 45 o p p o r t u n i t y to see many p i c t u r e s of astrona u t s walking i n space s u i t s on the moon, why would they b e l i e v e that o b j e c t s f l o a t on the moon, and secondly, what then do they p e r c e i v e the purpose of the space s u i t s to be, s i n c e they b e l i e v e that there i s a i r there? Because a i r e x i s t s on E a r t h , perhaps the n a t u r a l assumption i s " a l l p l a n e t a r y o b j e c t s must have a i r . ' T h i s being so, then the space s u i t may " i n t h e i r eyes' serve other f u n c t i o n s such as "keeping the ast r o n a u t s from f l o a t i n g " . Four of the s i x students made r e f e r e n c e to g r a v i t y when e x p l a i n i n g t h e i r p r e d i c t i o n s f o r the motion of b a l l s on the moon. Three s u b - c a t e g o r i e s of responses are found. John b e l i e v e s that there i s l e s s g r a v i t y found on the moon. He e x p l a i n e d "because there i s l e s s g r a v i t y there (moon), the he a v i e r o b j e c t would j u s t n a t u r a l l y f a l l f a s t e r than the l i g h t o b j e c t . " T h i s statement has s e v e r a l i m p l i c a t i o n s . John, as i n the f i r s t task, " c o r r e c t l y ' b e l i e v e s that the moon has g r a v i t y , and that i t i s l e s s than that of E a r t h . Secondly, he b e l i e v e s that "heavier b a l l s j u s t n a t u r a l l y f a l l f a s t e r than l i g h t e r b a l l s ' . T h i s statement i s i n c o n t r a d i c t i o n to h i s p r e d i c t i o n of what happens on E a r t h , where a l l o b j e c t s f a l l at the same r a t e because g r a v i t y p u l l s the same. T h i s " n a t u r a l s t a t e ' i s o b v i o u s l y dependent upon the s i t u a t i o n a l context, and i s found on the moon, but not on the E a r t h . F u r t h e r i n v e s t i g a t i o n r e v e a l s the reason f o r h i s apparent c o n t r a d i c t i o n . 46 The second sub-category of r e f e r e n c e to g r a v i t y i s one where g r a v i t y i s the r e s p o n s i b l e agent f o r o b j e c t s f l o a t i n g on the moon. Without the g r a v i t y , i t i s i n f e r r e d that the "nat u r a l s t a t e ' where o b j e c t s " f a l l to the ground' would e x i s t . P e t e r ' s e x p l a n a t i o n s are c o n s i s t e n t with h i s e x p l a n a t i o n g i v e n i n task #1 on the moon. The t h i r d sub-category of r e f e r e n c e to g r a v i t y i s one where g r a v i t y does not e x i s t on the moon, giv e n by Roy. 3.2.5 in, a Space C r a f t The i n t e r v i e w e r asked the students to p r e d i c t "What would happen i f I were t o do the same experiment i n a space c r a f t i n outer space?" T h e i r p r e d i c t i o n s and ex p l a n a t i o n s c l o s e l y resembled the responses g i v e n i n the previous task being on the moon. F i v e students b e l i e v e d that the b a l l s "would f l o a t " or "would j u s t stay t h e r e " . T h e i r e x p l a n a t i o n s were very s i m i l a r as to the previous task, three making r e f e r e n c e to t h ere being no g r a v i t y i n space, and two making r e f e r e n c e to the a i r being d i f f e r e n t . The other student, John, b e l i e v e d that the b a l l s would f a l l at the same speed. T h i s seems to be i n apparent c o n t r a d i c t i o n to what he p r e d i c t e d f o r the moon, where the he a v i e r b a l l n a t u r a l l y f e l l f a s t e r . H is e x p l a n a t i o n was " I t 47 i s k i n d of the same as ea r t h , i t i s an enclosed space." I t i s as i f the o u t s i d e boundaries surrounding the E a r t h (the atmosphere), or the w a l l s of the space s h i p cause a pre s s u r e t h a t i s r e s p o n s i b l e f o r the degree of g r a v i t y present. John d i d not b e l i e v e that the moon had an atmosphere and t h e r e f o r e he c a l l e d i t an "open space". In open spaces there i s l e s s g r a v i t y , and then the " n a t u r a l * s t a t e e x i s t s . In contexts where the "nat u r a l s t a t e ' e x i s t s , h e a v i e r o b j e c t s w i l l f a l l f a s t e r . In contexts that are enclosed spaces, g r a v i t y i s s t r o n g e r , and the "nat u r a l s t a t e ' doesn't e x i s t any longer. In these c o n t e x t s , g r a v i t y p u l l s a l l o b j e c t s e q u a l l y . A c h i l d ' s s e t of p r e d i c t i o n s are not n e c e s s a r i l y i l l o g i c a l or i n c o n s i s t e n t because a s c i e n t i s t deems them to be so. Because the c r i t e r i a that a s c i e n t i s t s p e r c e i v e s as p r o v i d i n g coherence to a theory i s very d i f f e r e n t than t h a t of a c h i l d , i t i s imperative that an i n t e r v i e w e r p r o v i d e o p p o r t u n i t y f o r thorough probing to e l i c i t e x h a u s t i v e l y , a l l the parameters p e r t a i n i n g to the theory. T h i s p a r t i c u l a r student's response p r o v i d e s a case at hand. 3.2.6 Summary of the Data As would be expected, a l l s i x students p r e d i c t e d that the b a l l would f a l l when " l e t go'. ; Four students r e a d i l y e x p l a i n e d that i t was because of g r a v i t y that i t happened 48 that way. One mentioned that i t i s because i t s "heavy" that i t f a l l s , and one mentioned that i t i s because i t can't f l o a t on the E a r t h that i t f a l l s . Three students p r e d i c t e d that when the two b a l l s of d i f f e r e n t mass are " l e t go' at e x a c t l y the same time that they w i l l f a l l at d i f f e r e n t speeds. T h i s i s a commonly h e l d b e l i e f that p e r s i s t s even i n a d u l t s . T h e i r reason f o r t h i s happening i s because of "heaviness". Of the three students p r e d i c t i n g that the b a l l s would f a l l at the same speed one claimed "the p u l l of g r a v i t y i s the same". Another s a i d " i t d i d n ' t have time to p i c k up speed." The t h i r d student o f f e r e d no e x p l a n a t i o n . The s t u d e n t s ' n o t i o n s of g r a v i t y on the moon remained the same as i n the pre v i o u s task. I t proved worthwhile to present the same context again i n t h i s task so that the c o n s i s t e n c y with which the student use t h e i r t h e o r i e s c o u l d be checked. They a l l remained c o n s i s t e n t . John was abl e to add some d e t a i l to h i s scheme of g r a v i t y , i n the context of the moon, by c l a i m i n g that the h e a v i e r b a l l would f a l l f a s t e r , (whereas on the E a r t h , the two would f a l l at the same r a t e ) The reason o f f e r e d was that the moon was a r e g i o n of l e s s g r a v i t y , and i n such r e g i o n s , h e a v i e r o b j e c t s n a t u r a l l y f a l l f a s t e r . John's n o t i o n s of g r a v i t y i n space a l s o remained the same as i n the pre v i o u s task. 49 There was c o n s i s t e n c y of response from task to task as well as from the context of the moon to the context of the space c r a f t . Comparing ideas across tasks i s b e n e f i c i a l i n e l i c i t i n g the d e t a i l s of t h e i r t h e o r i e s , otherwise not a t t a i n e d . 3.3 Task #3: V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube 3.3.1 i n t r o d u c t i o n Because r e s e a r c h shows that many c h i l d r e n ' s t h e o r i e s of g r a v i t y i n d i c a t e that g r a v i t y i s absent from water, i t was of i n t e r e s t to i n c l u d e t h i s task as one of the three to be s t u d i e d . The i n t e r v i e w e r used a d i f f e r e n t s et of b a l l s to conduct t h i s l a s t task, s i n c e the wood b a l l would j u s t f l o a t i n the water. The two b a l l s used were metal and p l a s t i c , both of n e a r l y i d e n t i c a l diameter, and both s m a l l e r than what were used i n the previous two t a s k s . The two water-f i l l e d tubes were approximately one metre i n le n g t h , e i g h t centimetres i n diameter, and contained about three l i t r e s of water when f i l l e d . These tubes were p l a c e d on the counter at near t a b l e h e i g h t . The i n t e r v i e w p r o t o c o l f o r task #3 i s shown i n Table IX. 50 TABLE IX Interview P r o t o c o l of Task #3 Part 1: One B a l l a. OBSERVATION Have the student examine these two b a l l s and ask: * What can you t e l l me about these b a l l s ? b. PREDICTION: Holdin g one b a l l at the top of the tube, ask: * What w i l l happen i f I l e t go of t h i s b a l l ? b. EXPLANATION: Before l e t t i n g go of the b a l l , ask: * Why do you t h i n k that w i l l happen? Having l e t go of the b a l l i n v i t e a d i s c u s s i o n on the nature of g r a v i t y i n t h i s s e t t i n g . * Does t h i s f l u i d a f f e c t the way the b a l l f a l l s ? P art 2: Two B a l l s a. PREDICTION: Holdin g the two b a l l s over the top of the tubes, ask: * What w i l l happen i f I l e t go of both of these b a l l s at the same time? b. EXPLANATION: Before l e t t i n g go of the b a l l s , ask: * Why do you t h i n k that w i l l happen? c. EXPERIMENTATION: Have the student take the two b a l l s and conduct the experiment. d. OBSERVE & EXPLAIN: Have the student d e s c r i b e what he saw happen. Have the student o f f e r an e x p l a n a t i o n f o r what he saw. e. HYPOTHETICAL SITUATION In order to tease out f u r t h e r i n t u i t i v e knowledge that students possess of g r a v i t y and motion, the s u b j e c t i s asked: * What would happen i f I were to do t h i s experiment on the moon? Fu r t h e r the d i s c u s s i o n by s e t t i n g the context of the experiment to take p l a c e on a space c r a f t i n outer space, and ask t h i s q u e s t i o n : * What would happen i f I were to do t h i s experiment on a space c r a f t i n outer space? f. CONCLUDING REMARKS Have the s u b j e c t s o f f e r any general t h e o r i e s on the nature of g r a v i t y , and i t s e f f e c t s on the motion of o b j e c t s of d i f f e r e n t mass by a s k i n g : * What do you know now about the way o b j e c t s f a l l i n f l u i d - f i l l e d tubes? Have the s u b j e c t s w r i t e down t h e i r ideas and t h e o r i e s on an i n t e r v i e w card. 51 3.3.2 One B a l l F a l l i n g i n Water The i n t e r v i e w e r handed two b a l l s to the student, one metal and one p l a s t i c . Each student was asked to examine the b a l l s and to " t e l l me what you can about these b a l l s . " I n v a r i a b l y , one of the f i r s t comments made mentioned the d i f f e r e n c e of t h e i r weights. C o l o r , nature of m a t e r i a l s , and s i z e were a l s o r e f e r r e d t o . When the i n t e r v i e w e r p i c k e d up the metal b a l l and h e l d i t above one of the tubes and asked, "What w i l l happen i f I l e t go of t h i s b a l l ? " , a l l s i x responses were s i m i l a r s a y i n g that the b a l l would " s i n k " or "drop". Table X c o n t a i n s a l i s t of the p r e d i c t i o n s of the students. Table XI l i s t s summarized student p r e d i c t i o n s . Table XII shows the students' answers when asked, "Why do you t h i n k that w i l l happen?" When asked, "Why do you t h i n k that w i l l happen?" four c a t e g o r i e s of responses were i n d i c a t e d . Two students r e f e r r e d to g r a v i t y as the cause. John s a i d " I t would s i n k because of the p r e s s u r e of g r a v i t y . " I t i s of i n t e r e s t to note the use of the word "pressure' because t h i s same student made mention that e n c l o s e d spaces have more pr e s s u r e , and t h e r e f o r e g r a v i t y i s g r e a t e r . The other student, Peter, t a l k e d of g r a v i t y p u l l i n g i t down. 52 TABLE X Task #3: P r e d i c t i o n s of V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube LETTING GO OF ONE BALL Student # P r e d i c t i o n s 1 I t would s i n k . 2 It would s i n k . 3 I t would s i n k to the bottom. 4 I t would f a l l t o the bottom. 5 It would s i n k . 6 It would drop. LETTING GO OF BOTH BALLS AT THE SAME TIME Student # P r e d i c t i o n s 1 The h e a v i e r one would go f a s t e r . 2 The h e a v i e r one would go f a s t e r . 3 The h e a v i e r b a l l would f a l l f a s t e r . 4 The h e a v i e r b a l l would f a l l f a s t e r . 5 The h e a v i e r b a l l would f a l l f a s t e r . 6 The h e a v i e r one would drop f i r s t . LETTING GO OF BOTH BALLS ON THE MOON Student # P r e d i c t i o n s 1 The h e a v i e r b a l l would go f a s t e r . 2 The he a v i e r b a l l would s i n k f a s t e r . 3 The b a l l would s t i l l f l o a t , and the g r a v i t y might p u l l the water out. 4 They would stay i n the box. 5 They would f l o a t . 6 They would f l o a t around. LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # P r e d i c t i o n s 1 The h e a v i e r b a l l w i l l s i n k f a s t e r . 2 The h e a v i e r b a l l w i l l s i n k f a s t e r . 3 The b a l l s would s t a y and the water might p u l l up. 4 They would stay i n the box. 5 They wouldn't go down. 6 They would f l o a t . 53 TABLE XI P r e d i c t i o n Summary of Task #3 Student # 1 B a l l 2 B a l l s On the Moon In Space 1 s i n k h e a v i e r f a s t e r h e a v i e r f a s t e r h e a v i e r f a s t e r 2 s i n k h e a v i e r f a s t e r h e a v i e r f a s t e r h e a v i e r f a s t e r 3 s i n k h e a v i e r f a s t e r f l o a t f l o a t 4 s i n k h e a v i e r f a s t e r f l o a t f l o a t 5 s i n k h e a v i e r f a s t e r f l o a t f l o a t 6 s i n k h e a v i e r f l o a t f l o a t f a s t e r 54 TABLE XII Task #3: E x p l a n a t i o n s of P r e d i c t i o n s of V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube Student # 1 2 3 5 6 Student # 1 LETTING GO OF ONE BALL Ex p l a n a t i o n s I t would s i n k because of the pressure of g r a v i t y . I t would s i n k because of t h e i r weight. It would s i n k to the bottom because g r a v i t y p u l l s i t down. It would f a l l to the bottom because i t s heavy. I t would s i n k because i t s h e a v i e r . I t would drop because small rocks drop. LETTING GO OF BOTH BALLS AT THE SAME TIME Ex p l a n a t i o n s The h e a v i e r one would go f a s t e r because i t ' s h e a v i e r and there i s l e s s g r a v i t y i n water. The h e a v i e r one would go f a s t e r because i t i s not the same p r i n c i p l e as g r a v i t y , i t ' s l i k e the h e a v i e r you are the f a s t e r you w i l l s i n k . The water takes over f o r the g r a v i t y and i t depends on who heavy the o b j e c t i s that you are dropping. 3 4 5 6 The h e a v i e r b a l l weighs more. The h e a v i e r b a l l i t ' s h e a v i e r . would f a l l f a s t e r because i t would f a l l f a s t e r because The h e a v i e r b a l l would f a l l f a s t e r because of the weight i t has. The h e a v i e r one would drop f i r s t because i t ' s h e a v i e r and i t has more weight on i t to drop. LETTING GO OF BOTH BALLS ON THE MOON Student # 1 2 3 E x p l a n a t i o n s The h e a v i e r b a l l would go f a s t e r because there i s not as much g r a v i t y on the moon and not as much g r a v i t y as there i s i n water e i t h e r . The h e a v i e r b a l l would s i n k f a s t e r because i f o b j e c t s are h e a v i e r than water they s i n k . The b a l l would s t i l l f l o a t and g r a v i t y would take the water out; p u l l i t out. 55 4 They would stay i n the box because there i s no a i r on the moon. There i s no g r a v i t y on the moon. 5 They would f l o a t because there i s not the a i r f o r c e that goes down. 6 They would f l o a t around because the a i r and s t u f f i s d i f f e r e n t . LETTING GO OF BOTH BALLS IN A SPACE CRAFT Student # E x p l a n a t i o n s 1 The h e a v i e r b a l l would s i n k f a s t e r because water has l e s s g r a v i t y . 2 The h e a v i e r b a l l w i l l s i n k f a s t e r because h e a v i e r o b j e c t s s i n k f a s t e r . 3 The b a l l s would s t a y and the water might p u l l up. 4 They would stay i n the box because th e r e i s no g r a v i t y because there i s no a i r . 5 They wouldn't go down because there i s not the a i r f o r c e that goes down. 6 They would f l o a t because the a i r i s d i f f e r e n t . 56 Another category of response r e f e r r e d to i t s s i n k i n g because i t was " h e a v i e r " or "heavy". Again, i t seems that the p r o p e r t y of "heaviness' causes o b j e c t s to have motion j u s t as g r a v i t y does. Perhaps heaviness can be i n t e r p r e t e d as a p r o p e r t y that enables o b j e c t s to move apart from an o u t s i d e f o r c e . Another e x p l a n a t i o n f o r the b a l l s i n k i n g , was "because of t h e i r weight". I t i s d i f f i c u l t to know i f heaviness and weight are used synonymously, but they are used i n a s i m i l a r manner, where the e x p l a n a t i o n g i v e n by the student i s not accompanied by any mention of an o u t s i d e f o r c e a c t i n g on the b a l l . Linda's e x p l a n a t i o n f o r the b a l l s i n k i n g was "because small rocks drop." Her mentioning of a s i m i l a r f a m i l i a r a c t i o n that she had p e r s o n a l l y observed, seems to c o n s t i t u t e a reason f o r a l l other s i m i l a r a c t i o n s o c c u r r i n g . T h e r e f o r e , t h i s student does not f e e l compelled to e x p l a i n "why" t h i s happens. 3.3.3 Two B a l l s F a l l i n g i n Water, The i n t e r v i e w e r posed the q u e s t i o n "What would happen i f I l e t go of both of these b a l l s at e x a c t l y the same time?" A l l responses were of the same category, where "the h e a v i e r b a l l would f a l l f a s t e r " . The unanimity of the response 57 r e v e a l s that the phenomenon i s l i k e l y to be commonly observed by most c h i l d r e n . When asked, "Why do you th i n k that w i l l happen?" the responses were more v a r i e d . One student, Karen, was s a t i s f i e d by the e x p l a n a t i o n "because i t ' s h e a v i e r " . Three other students used weight as an e x p l a n a t i o n f o r i t f a l l i n g f a s t e r , s a y i n g " i t weighs more", " i t has more weight", and "because of the weight i t has". None of the above students made any mention of g r a v i t y . The re s e a r c h e r i s not sure at t h i s p o i n t , i f t h i s i s because they do not b e l i e v e g r a v i t y e x i s t s i n water, or i f i t be because t h e i r conceptual framework does not connect g r a v i t y t o f a l l i n g i n water. F u r t h e r responses may c l a r i f y t h i s . A second category of e x p l a n a t i o n was o f f e r e d by one John whose response to the h e a v i e r b a l l f a l l i n g f a s t e r i n water was "because i t s h e a v i e r , and there i s l e s s g r a v i t y i n water." G r a v i t y , i t seems, i s context dependent f o r i t s s t r e n g t h . John a l s o b e l i e v e s that there i s l e s s g r a v i t y on the moon s i n c e i t i s an open space. A c c o r d i n g l y , he p r e d i c t e d that o b j e c t s f a l l i n g i n regions of l e s s g r a v i t y w i l l r e s u l t i n the he a v i e r one f a l l i n g f a s t e r . H is p r e d i c t i o n i s d e f i n i t e l y c o n s i s t e n t with h i s unique theory. A t h i r d category, and a most i n t e r e s t i n g e x p l a n a t i o n was o f f e r e d by Roy who s a i d , "The h e a v i e r one would go f a s t e r because i t i s not the same p r i n c i p l e as g r a v i t y . I t ' s l i k e the h e a v i e r you are the f a s t e r you w i l l s i n k . The water takes over f o r the g r a v i t y and i t depends on how heavy the o b j e c t i s that you are dropping." He had claimed e a r l i e r , t h a t o b j e c t s of d i f f e r e n t mass f a l l at the same r a t e . I t i s i n t e r e s t i n g t o note how thorough h i s e x p l a n a t i o n was i n order to account f o r a f a m i l i a r s i t u a t i o n that was so d i f f e r e n t from f r e e - f a l l i n a i r . His theory i n f e r s that g r a v i t y does not e x i s t i n water, nor i s necessary f o r f a l l i n g to occur. I suppose that i f i t d i d e x i s t i n water, he would have had a d i f f i c u l t time accounting f o r the f a c t t h a t h e a v i e r o b j e c t s f a l l f a s t e r . Water then becomes the c a u s a t i v e agent i n t h i s case, and i s "not the same p r i n c i p l e " . In the " f o r c e ' of water, heaviness i s a f a c t o r t h at does determine speed. The complexity of h i s theory becomes more evident as he e x p l a i n s i t i n the s e t t i n g on the moon and i n space. 3.3.4 Qn the Moon When asked by the i n t e r v i e w e r , "What would happen i f I d i d t h i s experiment on the moon?" two c a t e g o r i e s of responses were presented. Four students c l a i m that the b a l l s would not go down i n t o the water; they would j u s t s t ay t h e r e . Of these students, Peter claimed that the water i n the tubes may even be p u l l e d out. The other two students claimed that the h e a v i e r b a l l would go f a s t e r . 59 When the i n t e r v i e w e r asked, "Why do you thin k that w i l l happen?" a v a r i e t y of responses were g i v e n . Three students made r e f e r e n c e to the a i r : "there i s no a i r on the moon", "the r e i s not the a i r f o r c e that goes down", and "the a i r and s t u f f i s d i f f e r e n t " . The connection between a i r and the presence of g r a v i t y i s very s t r o n g . Karen d i d r e f e r to the f a c t that there was no g r a v i t y on the moon. Peter, c o n s i s t e n t with p r e v i o u s e x p l a n a t i o n s , claimed that the g r a v i t y on the moon would make the b a l l s f l o a t . John e x p l a i n e d "There i s not as much g r a v i t y on the moon and not as much g r a v i t y as there i s i n water e i t h e r . " T h i s response i s s i m i l a r to pre v i o u s responses g i v e n by him. The s i x t h student, Roy, who claims that there i s no g r a v i t y on the moon, and who a l s o claims i n t h i s task that water takes over f o r g r a v i t y , s a i d "the h e a v i e r b a l l would s i n k f a s t e r because i f o b j e c t s are h e a v i e r than water they s i n k . " H i s statement not only i s c o n s i s t e n t to other p r e d i c t i o n s and e x p l a n a t i o n s made, but i t a l s o g i v e s a reason f o r " s i n k i n g i n water' that c l o s e l y resembles the c o r r e c t reason. His e x p l a n a t i o n was the only one t h a t attempted to e x p l a i n "why some o b j e c t s s i n k ' when other o b j e c t s f l o a t . 60 3.3.5 In a Space C r a f t The i n t e r v i e w e r posed the q u e s t i o n , "What would happen i f I were to do t h i s experiment on a space c r a f t i n outer space?" Again, s i m i l a r t o what was p r e d i c t e d would happen on the moon, four of the students s a i d "they would f l o a t " or "they would s t a y t h e r e " or "they wouldn't go down". The other students p r e d i c t e d that the h e a v i e r b a l l would go f a s t e r . When the i n t e r v i e w e r asked those .who p r e d i c t e d that they would f l o a t , "Why do you t h i n k that w i l l happen?", three made r e f e r e n c e to the a i r ; and one r e f e r r e d again to g r a v i t y p u l l i n g i t so that i t would f l o a t . Of the two students who p r e d i c t e d that the b a l l s would f a l l , John e x p l a i n e d that g r a v i t y e x i s t e d i n enclosed spaces so that i t would f a l l l i k e i t d i d on E a r t h . Roy, who claimed that g r a v i t y i s not i n water, s a i d "because h e a v i e r o b j e c t s s i n k f a s t e r " . Because most c h i l d r e n conceive the moon and outer space as having the same c o n d i t i o n s of g r a v i t y , one can compare responses between the two contexts i n order to check the degree of c o n s i s t e n c y i n c h i l d r e n ' s t h e o r i e s . 61 3.3.6 Summary of the Pata A l l s i x students p r e d i c t e d that the b a l l would s i n k i n the water. Two of the student r e f e r r e d to g r a v i t y has a cause; one to "heaviness', one to weight. One student made r e f e r e n c e to a s i m i l a r s i t u a t i o n comparing outcomes, i n order to make her p r e d i c t i o n . A l l s i x students a l s o p r e d i c t e d that the he a v i e r b a l l would drop f a s t e r i n the water. Three c a t e g o r i e s of response were i n d i c a t e d . In one category, weight or "heaviness" i s given as an e x p l a n a t i o n . In another category, " l e s s g r a v i t y ' was gi v e n as a reason f o r the two f a l l i n g at d i f f e r e n t r a t e s . The l a s t category i n v o l v e d "another p r i n c i p l e ' i n which water causes an o b j e c t to f a l l apart from g r a v i t y . E v i d e n t l y , the p u l l of water operates i n regions of no g r a v i t y , and p u l l s h e a v i e r o b j e c t s more than l i g h t e r ones. On the moon, four students p r e d i c t e d that the b a l l s would f l o a t . They reasoned that the d i f f e r e n c e i n a i r was the reason. The remaining two students s a i d that the h e a v i e r b a l l would s i n k f a s t e r . They each o f f e r e d a d i f f e r e n t e x p l a n a t i o n . The one claims that there i s l e s s g r a v i t y i n water, and a c c o r d i n g l y , i t w i l l p u l l h e a v i e r o b j e c t s more. The other claims that water p u l l s h e a v i e r o b j e c t s more when i n water, r e g a r d l e s s of the presence of g r a v i t y . 62 The r e s u l t s on the space c r a f t were c o n s i s t e n t again across t a s k s and across contexts w i t h i n a task. Pour p r e d i c t e d that they would f l o a t ; three r e f e r r i n g to a i r , and one to the p u l l of g r a v i t y as an e x p l a n a t i o n . Again, the other two p r e d i c t e d t h at the h e a v i e r b a l l would s i n k f a s t e r on a space c r a f t . One e x p l a n a t i o n claims that the water takes over f o r g r a v i t y , and the other claims that because the space c r a f t i s an "enclosed space' , g r a v i t y e x i s t s l i k e i t does on the E a r t h . 63 CHAPTER IV DISCUSSION OF THE RESULTS The r e s u l t s of the data w i l l be reviewed s e p a r a t e l y across each task. P r i o r to the d i s c u s s i o n of the r e s u l t s , a b r i e f summary of the r e s u l t s i s f i r s t presented. 4.1 Task #1: The in c l i n e d Plane 4.1.1 Summary of the R e s u l t s of Task #1 4.1.1.1 One B a l l A l l students p r e d i c t e d that when the b a l l i s l e t go on top of the ramp, that i t would r o l l down. 4.1.1.2 Two B a l l s A l l students except #2 p r e d i c t e d that when the two b a l l s are l e t go on top of the ramp, that the hea v i e r one would r o l l f a s t e r . Student #2 who p r e d i c t e d that they would r o l l at the same speed a l s o p r e d i c t e d that they would f a l l f r e e - f a l l at the same speed i n task #2. 4.1.1.3 On the Moon A l l students except #1 p r e d i c t e d that when the b a l l s are l e t go on top of the ramp on the moon, that they would f l o a t . 64 * Two students (#2 & #4) e x p l a i n e d that there i s no g r a v i t y on the moon. * Two students (#5 & #6) e x p l a i n e d that the a i r was d i f f e r e n t on the moon, so that they would f l o a t . * One student (#3) s a i d that g r a v i t y on the moon p u l l i n g from the E a r t h makes them f l o a t . * #1 claimed that there was l e s s g r a v i t y on the moon. 4.1.1.4 in Space The p r e d i c t i o n s f o r the space c r a f t i n outer space were the same as f o r the moon. * #1 claimed that because the space c r a f t was an "enclosed space' c o n d i t i o n s such as on E a r t h would e x i s t . However, o u t s i d e of the space c r a f t , there would be no g r a v i t y . 4.1.2 D i s c u s s i o n of the R e s u l t s of Task #1 The motion of b a l l s on an i n c l i n e d plane i s p e r c e i v e d as o p e r a t i n g under a d i f f e r e n t s e t of c r i t e r i a than f o r that of the other two t a s k s . Nearly a l l of the students (5 out of 6) p r e d i c t e d that the h e a v i e r b a l l should t r a v e l f a s t e r down the s l o p e . Because they f e l t that the b a l l s would not do the same t h i n g on the moon, they e v i d e n t l y a t t r i b u t e the downward motion to some f o r c e that i s unique to the e a r t h . Pour of the s i x students b e l i e v e d that the f o r c e causing the b a l l s to r o l l down the s l o p e i s absent on the moon. There 65 i s a d e f i n i t e connection of " f o r c e ' (be i t g r a v i t y or otherwise) to the atmosphere. Two of the students suggested that the a i r there was d i f f e r e n t , causing the b a l l s to f l o a t . Another student suggested that the lack of g r a v i t y was because of the moon being an "open space'. The students (6 out of 6) p e r c e i v e d no general d i f f e r e n c e i n the c o n d i t i o n s of f o r c e found i n the context of space to th a t found on the moon. Most of the students (4 out of 6) suggested that g r a v i t y i s only found on the E a r t h . At some unknown p o i n t away from the E a r t h g r a v i t y d i s a p p e a r s . Two students b e l i e v e that g r a v i t y does e x i s t elsewhere i n the u n i v e r s e . One b e l i e v e s that the s t r e n g t h of the g r a v i t y i s dependent upon the p l a c e being "enclosed' or not. The other student see g r a v i t y as reachin g out from the E a r t h f a r out i n t o space, p u l l i n g o b j e c t s o f f the moon or the space c r a f t , and h o l d i n g them o f f the ground so that they w i l l f l o a t . Two of the students see the downward motion of o b j e c t s as a n a t u r a l motion that happens anywhere i n the u n i v e r s e . It i s the presence of g r a v i t y that determines e i t h e r the s t r e n g t h of the motion, or the d i r e c t i o n of the motion. 66 4.2 Task #2 V e r t i c a l F r e e - f a l l 4.2.1 Summary of the R e s u l t s of Task #2 4.2.1.1 One B a l l As i n task #1 a l l the students again p r e d i c t e d that when the b a l l was l e t go, i t would f a l l . 4.2.1.2 Two B a l l s Three of the students (#1, #2, & #5) p r e d i c t e d that when two b a l l s of d i f f e r e n t mass are dropped at the same time, they would f a l l at the same speed. Three of the students (#3, #4, & #6) p r e d i c t e d that when two b a l l s of d i f f e r e n t mass are dropped at the same time, that they would f a l l at d i f f e r e n t speeds, the h e a v i e r b a l l f a l l i n g f a s t e r . 4.2.1.3 On the Moon A l l the students except #1 p r e d i c t e d that the b a l l s would f l o a t on the moon. T h i s i s c o n s i s t e n t with the p r e d i c t i o n s g i v e n i n task #1. * Student #1 e x p l a i n e d that because the moon was a r e g i o n of l e s s e r g r a v i t y , that when the two b a l l s f e l l , they would n a t u r a l l y f a l l at d i f f e r e n t r a t e s because of t h e i r d i f f e r e n t weights. 67 * Two students, the same two students as i n task #1 f o r the moon (#2 & #4), again gave the same e x p l a n a t i o n that there was no g r a v i t y on the moon. * Two students, the same two students as i n task #1 f o r the moon (#5 & #6) again gave the same e x p l a n a t i o n that the a i r was d i f f e r e n t . * One student, the same student as i n task #1 f o r the moon (#3) again gave the same e x p l a n a t i o n that g r a v i t y would make them f l o a t on the moon. 4.2.1.4 In Space The r e s u l t s of the p r e d i c t i o n s and ex p l a n a t i o n s g i v e n i n t h i s task are c o n s i s t e n t with what was presented i n the pre v i o u s task. 4.2.2 D i s c u s s i o n of the R e s u l t s of Task #2 Some of the students p e r c e i v e d that a d i f f e r e n t s et of p r i n c i p l e s were o p e r a t i n g when o b j e c t s f a l l f r e e l y i n a i r than when r o l l i n g down a s l o p e . They (3 out of 6) f e l t that o b j e c t s of d i f f e r e n t mass would f a l l at the same r a t e . One of the three suggested that g r a v i t y p u l l s a l l o b j e c t s e q u a l l y . It i s not evident i f the other three students p e r c e i v e d the two tasks to be o p e r a t i n g under d i f f e r e n t p r i n c i p l e s (than task #2) or not s i n c e t h e i r p r e d i c t i o n s i n t h i s task were i d e n t i c a l to the p r e d i c t i o n s i n the previous one. 68 G r a v i t y was more r e a d i l y mentioned as the cause of the f a l l of the b a l l s " i n t h i s task than i n the previous one (4 out of 6). Of the three tasks conducted, t h i s task had the most r e f e r e n c e s to g r a v i t y as a cause f o r downward motion of the b a l l s . Consequently, the use of g r a v i t y as a c a u s a t i v e agent i n the downward motion of b a l l s i s dependent on the context. Research i n d i c a t e s that f o r many of c h i l d r e n ' s t h e o r i e s , the schema e l i c i t e d are context dependent. 4.3 Task #3: V e r t i c a l F a l l i n a F l u i d - f i l l e d Tube 4.3.1 Summary of the R e s u l t s of Task #3 4.3.1.1 One B a l l A l l the students p r e d i c t e d that i f a b a l l were " l e t go' above a f l u i d - f i l l e d tube that i t would s i n k to the bottom. 4.3.1.2 Two B a l l s A l l the students p r e d i c t e d that i f both b a l l s of d i f f e r e n t mass were r e l e a s e d above the f l u i d - f i l l e d tube, that the h e a v i e r b a l l would s i n k f a s t e r than the l i g h t e r b a l l . 4.3.1.3 On the Moon Two of the students (#1 and #2) p r e d i c t e d that the same t h i n g would happen on the moon. 69 * #1 e x p l a i n e d , c o n s i s t e n t with p r e v i o u s e x p l a n a t i o n s f o r the moon, s i n c e i t i s a r e g i o n of l e s s g r a v i t y , the he a v i e r b a l l would go f a s t e r . * #2 e x p l a i n e d that " f a l l i n g i n water doesn't depend on g r a v i t y , ' so even on the moon, the water would take over. And l i k e o b j e c t s on the E a r t h f a l l i n g i n water, the h e a v i e r b a l l would f a l l f a s t e r . * #3 e x p l a i n e d that g r a v i t y would make the b a l l f l o a t , c o n s i s t e n t with h i s other p r e d i c t i o n s about the moon, and that g r a v i t y may even p u l l the water out of the tube. * #4 e x p l a i n e d that there i s no g r a v i t y on the moon so nothing would happen, c o n s i s t e n t with the e x p l a n a t i o n s g i v e n f o r the moon i n task #1 and #2. * #5 & #6 e x p l a i n e d that the a i r was d i f f e r e n t so they would f l o a t . T h e i r e x p l a n a t i o n s are c o n s i s t e n t with that of tasks #1 & #2. 4.3.1.4 In Space Two of the students (#1 & #2) again p r e d i c t e d as they d i d f o r the moon, that the he a v i e r o b j e c t would s i n k f a s t e r than the l i g h t e r o b j e c t . * #l's e x p l a n a t i o n i s "because water has l e s s g r a v i t y ' . When i n l e s s g r a v i t y the he a v i e r o b j e c t n a t u r a l l y f a l l s f a s t e r . A l s o , because the space c r a f t i s an enclosed space, there w i l l be g r a v i t y there l i k e on the E a r t h . 70 * #2's e x p l a n a t i o n , c o n s i s t e n t with what he s a i d f o r the moon, i s that g r a v i t y i s not necessary i n water, so then even i n outer space, where there i s no g r a v i t y , the b a l l s w i l l s i n k l i k e they do on E a r t h with the he a v i e r one f a l l i n g f a s t e r . * #3 again commented about the p u l l of g r a v i t y from the Ea r t h , which may p u l l the water out of the tubes l i k e on the moon. * #4 again mentioned that there i s no g r a v i t y i n space. * #5 & #6 again mentioned that the a i r was d i f f e r e n t i n space so that the b a l l s would f l o a t . 4.3.2 D i s c u s s i o n of the R e s u l t s of Task #3 The context of water i s p e r c e i v e d by three of the s i x c h i l d r e n as o p e r a t i n g under another s e t of p r i n c i p l e s than those of the previous task. A l l s i x p r e d i c t e d that h e a v i e r b a l l s s i n k f a s t e r i n water than l i g h t e r b a l l s . As i n task #1, only two of the students mentioned that g r a v i t y i s the cause of o b j e c t s f a l l i n g i n water. The other students made re f e r e n c e to "weight' and "heaviness' as the cause of the o b j e c t s dropping. T h e i r e x p l a n a t i o n s f o r the h e a v i e r b a l l s i n k i n g f a s t e r were s i m i l a r as f o r one b a l l dropping i n the water (5 out of 6). One of the students, Roy, b e l i e v e s that water i s a f o r c e s i m i l a r to that of g r a v i t y i n that i t p u l l s o b j e c t s down, but d i f f e r e n t to that of g r a v i t y i n that i t p u l l s h e a v i e r o b j e c t s more than l i g h t e r o b j e c t s . His 71 concept sees "water* working independently of g r a v i t y , and t h e r e f o r e p r e d i c t s that o b j e c t s w i l l s i n k i n water anywhere i n the u n i v e r s e . 4.4 T h e o r i e s of G r a v i t y Even though there are many d i f f e r e n t components t o the t h e o r i e s of g r a v i t y h e l d by d i f f e r e n t c h i l d r e n , the d i f f e r e n t components are r e l a t e d i n t o common schema, or conceptual frameworks. See Table XIII f o r the components of c h i l d r e n ' s t h e o r i e s of g r a v i t y . The schema of g r a v i t y that c h i l d r e n possess are common across the world, f a l l i n g i n t o a few c a t e g o r i e s . Represented by t h i s study, were the f o l l o w i n g schema of g r a v i t y : a g e o c e n t r i c view of g r a v i t y , a human-centred view of g r a v i t y ( f u n c t i o n i n g only f o r human purposes), a scheme of g r a v i t y that depends on the presence of a i r , a scheme of g r a v i t y that depends on a space being enclosed, a scheme of g r a v i t y that i s not a f f e c t e d by the weight of o b j e c t s , and a scheme of g r a v i t y that i s a f f e c t e d by the weight of o b j e c t s . R e a l i z i n g that c h i l d r e n ' s schema of g r a v i t y are o f t e n u n i v e r s a l , the methods and c u r r i c u l a of s c i e n c e education need to r e f l e c t the knowledge of such schema. 72 TABLE XIII Components of the The o r i e s of G r a v i t y L o c a t i o n s Where G r a v i t y E x i s t s Number of Students 1. E a r t h only. 4 2. Enclosed spaces. 1 3. Many p l a c e s . 2 4. In a i r only. 4 5. Not i n water. 1 6. On the moon. 2 7. I t ' s everywhere. 1 Stre n g t h of G r a v i t y 1. Strong on the E a r t h . 6 2. Strong i n enclosed p l a c e s . 1 3. Weak on the moon. 1 4. Weak i n water. 1 5. Weak i n open p l a c e s . 1 Motion Caused by G r a v i t y 1. A l l o b j e c t s f a l l e q u a l l y as f a s t . 3 2. Heavier o b j e c t s f a s t e r than l i g h t e r o b j e c t s . 3 3. Objects f l o a t i f not on the E a r t h . 1 Nature of the Force 1. I t ' s a p u l l . 5 2. I t ' s a pr e s s u r e . 1 Components Necessary f o r G r a v i t y 1. A i r . 4 2. Something i n the a i r . 1 3. I t e x i s t s everywhere. 1 Frameworks of G r a v i t y 1. G r a v i t y causes weight which causes t h i n g s to f a l l . 4 2. G r a v i t y causes t h i n g s to f a l l or 1 weight causes t h i n g s to f a l l . 3. G r a v i t y causes weight which causes t h i n g s to f a l l 1 on E a r t h but causes t h i n g s to f l o a t elsewhere ( g e o c e n t r i c ) . 73 4.5 A Comparison of the Three Tasks Each of the three tasks i n v o l v e d d i f f e r e n t p h y s i c a l p r i n c i p l e s t h a t i n f l u e n c e d how g r a v i t y would a f f e c t the motion of b a l l s of d i f f e r e n t mass. Three of the students made the same p r e d i c t i o n across a l l three t a s k s , that h e a v i e r b a l l s f a l l f a s t e r . That i s a c o r r e c t p r e d i c t i o n f o r tasks one and t h r e e . Because t h e r e i s ample o p p o r t u n i t y f o r c h i l d r e n to observe the motion of b a l l s of d i f f e r e n t mass on a s l o p e and i n water, i t was expected that they would p r e d i c t a c c o r d i n g l y . However, i t i s very r a r e that an o p p o r t u n i t y would a r i s e where o b s e r v a t i o n of a task #2 phenomenon would occur. Such a s i t u a t i o n i n v o l v e s the two o b j e c t s as having equal s i z e ; the o b j e c t s being r e l e a s e d at e x a c t l y the same time ( t o the 100th of a second); and the observer being a b l e to observe the f a l l from s t a r t t o f i n i s h ( v e r i f y i n g s t a r t and f i n i s h ) . T h e r e f o r e , i t would not be unusual f o r a c h i l d to apply an outcome f o r what he commonly sees, (as i n task #1 and #3) to a s i t u a t i o n t h a t he has never encountered. In t h i s experiment, the unusual r e s u l t s , as p e r c e i v e d by the r e s e a r c h e r , were that three of the students d i d not p r e d i c t the same outcome f o r task #2 as they d i d i n task #1 and #3. What then would be the reason f o r them making a c o r r e c t p r e d i c t i o n ? " The students made no attempt to use school s c i e n c e e x p l a n a t i o n s . So the assumption i s "that the 74 students were not j u s t p a r r o t i n g a theory that they heard from a s c i e n c e l e s s o n . ' I f t h i s was t r u l y the case, then I ponder how a t h i r t e e n year o l d c h i l d c o u l d have developed such a theory of g r a v i t y , that would p r e d i c t the outcome of t h i s task c o r r e c t l y . Whether or not the other three students p e r c e i v e d the three tasks as i n v o l v i n g the same p r i n c i p l e s of g r a v i t y or not, can not be made evident from t h i s study. The t h e o r i e s that each c h i l d used from task to task, remained c o n s i s t e n t throughout the study. What at f i r s t was p e r c e i v e d by the re s e a r c h e r as an " i n c o n s i s t e n c y * was l a t e r e x p l a i n e d , r e v e a l i n g the c o n s i s t e n c y of the scheme. When the same context ( i e . the moon, the space c r a f t ) was presented i n a d i f f e r e n t task, the c h i l d r e n used very s i m i l a r l i n e s of reasoning unless the task r e q u i r e d them to do otherwise. 4.6 R e v i s i o n and C o n s t r u c t i o n of Ideas In g e n e r a l , the t h e o r i e s that the student used were h e l d to r i g i d l y . Even a f t e r making o b s e r v a t i o n s i n one task that c o u l d have i n f l u e n c e d a c h i l d to r e v i s e h i s / h e r ideas to accommodate the next task, the students h e l d t o t h e i r i d e a s . One student however, r e v i s e d three of h i s p r e d i c t i o n s i n l i g h t of a seemingly new theory that 75 developed d u r i n g the course of the i n t e r v i e w . Another student made a change of one pre v i o u s p r e d i c t i o n when he was fa c e d with an i n c o n s i s t e n c y . T h i s study would v e r i f y t h a t c h i l d r e n , even i n the face of c o n f l i c t i n g o b s e r v a t i o n a l evidence, h o l d to t h e i r t h e o r i e s q u i t e s t r o n g l y . Perhaps i t was the f a c t t h a t the student c o u l d d i s c u s s h i s t h e o r i e s out loud, that l e a d to the r e v i s i o n of i d e a s , r a t h e r than the f a c t t h at he had made o b s e r v a t i o n s of s c i e n t i f i c experiments. I f t h i s was the case, then v e r b a l i z a t i o n i s important to conceptual development and worthy of f u r t h e r i n v e s t i g a t i o n . 4.7 B i a s of Observations In the second task, where the students have o p p o r t u n i t y to p r e d i c t and then observe the outcome of two b a l l s of d i f f e r e n t mass f a l l i n g f r e e l y , a l l s i x students saw what they p r e d i c t e d they would see. In t h i s case, three of the students had to have seen " i n c o r r e c t l y ' . In each of these cases, the student had to make the " i n c o r r e c t ' o b s e r v a t i o n more than once. T h i s evidence s t r o n g l y confirms the l i t e r a t u r e , where students o b s e r v a t i o n s are the o r y - l a d e n , o b s e r v i n g what they expect to observe r a t h e r than what a c t u a l l y occurs. T h i s then would g i v e j u s t cause f o r s c i e n c e educators to re-examine the r o l e of "o b s e r v a t i o n ' i n the classroom. 76 CHAPTER V CONCLUSIONS AND IMPLICATIONS 5.1 The Three Tasks The primary purpose of the study was to e l i c i t s t u d e n t s ' conceptions of g r a v i t y and motion. By u s i n g the "demonstration-interview' technique, the r e s e a r c h e r was able to e l i c i t a r i c h sampling of conceptions from the s i x s t u d e n t s . At most, two of the s i x students had i d e n t i c a l schema of g r a v i t y , across the three tasks s t u d i e d , thus p r o v i d i n g a wide v a r i e t y of p o s s i b l e schema. There were t h e o r i e s e l i c i t e d demonstrating c l o s e connections of g r a v i t y with: the presence of a i r , components i n the a i r , the E a r t h , heaviness, weight, and "enclosed space'. The t h e o r i e s presented ranged i n academic development from being the " s e l f - c e n t e r e d ' p e r c e p t i o n s found i n young c h i l d r e n , to those demonstrating aspects of Newtonian p r i n c i p l e s found i n c o l l e g e - l e v e l p h y s i c s students.. C e r t a i n c o n t e x t u a l s i t u a t i o n s are more c l o s e l y l i n k e d to the f o r c e of g r a v i t y than o t h e r s . G r a v i t y was commonly made r e f e r e n c e of when d i s c u s s i n g o b j e c t s i n f r e e - f a l l , but r a r e l y made re f e r e n c e of when d i s c u s s i n g o b j e c t s f a l l i n g i n water. 77 The responses g i v e n by the students i n d i c a t e d t h at they p e r c e i v e d the tasks presented as i n v o l v i n g d i f f e r i n g p r i n c i p l e s of mechanics, but yet i n v o l v i n g g r a v i t y to some degree. Conducting the study across a range of three tasks proved b e n e f i c i a l i n a r t i c u l a t i n g a broad and d e t a i l e d conceptual framework of t h e i r i d e a s . Concepts t h a t were dependent upon the context of the task, c o u l d be r e v e a l e d when comparing them across d i f f e r e n t t a s k s . The range of tasks chosen proved to be a wise c h o i c e s i n c e many of the components s t r u c t u r e d i n t o t h e i r conceptual frameworks of g r a v i t y were c o n t e x t u a l l y dependent upon being i n water, on a s l o p e , or f a l l i n g f r e e l y . Another purpose of the study was to r e v e a l the ease or r e l u c t a n c y with which c h i l d r e n r e v i s e or c o n s t r u c t t h e o r i e s when faced with o b s e r v a t i o n a l evidence. Only one student's response i n d i c a t e d the r e c o n s t r u c t i o n of a theory d u r i n g the course of the i n t e r v i e w . The other c h i l d r e n r e v e a l e d no evidence f o r theory r e v i s i o n . I t seems that c h i l d r e n ' s t h e o r i e s r e s i s t r e v i s i o n even i n the face of c o n f l i c t i n g observable evidence. In accordance to t h e i r p r e d i c t i o n s , three of the students f a l s e l y observed that h e a v i e r b a l l s f e l l f a s t e r than l i g h t e r b a l l s , when f r e e l y f a l l i n g . As l i t e r a t u r e has c i t e d , o b s e r v a t i o n s do have elements of b i a s that are dependent upon one's t h e o r i e s . 78 The i n t u i t i v e t h e o r i e s that each c h i l d presented remained c o n s i s t e n t from task to task. W i t h i n the same context, both the p r e d i c t i o n s and the e x p l a n a t i o n s made by the students were remarkably i d e n t i c a l i n content. What may have seemed to be an i n c o n s i s t e n c y , proved to be a new component of a scheme that needed f u r t h e r e x p l a n a t i o n . The study does not wish to a t t r i b u t e any d i f f e r e n c e s i n student response to gender d i f f e r e n c e . Having a sample s i z e of s i x students i s too small to make any i m p l i c a t i o n s or g e n e r a l i z a t i o n s , even i f some d i s t i n c t i o n s of response were noted across gender. 5.2 Implications for Teaching Science T h i s study has g i v e n s t r o n g evidence to i n d i c a t e t h a t c h i l d r e n do not enter the classroom with a " b l a n k - s l a t e ' mind w a i t i n g to be i n s c r i b e d with knowledge. Instead they possess a mind f i l l e d w ith some t e n a c i o u s l y h e l d preconceptions of s c i e n t i f i c phenomenon. R e a l i z i n g that c h i l d r e n ' s a l t e r n a t e frameworks p e r s i s t i n s p i t e of the i n s t r u c t i o n o c c u r r i n g i n s c i e n c e classrooms, i t becomes impe r a t i v e that teachers are made aware of what these conceptions are. By doing so, they can s t r u c t u r e t h e i r l e s s o n s to make students aware of the short-comings of what they b e l i e v e . 79 The preconceptions h e l d by students may r e f l e c t many unique elements, but more i m p o r t a n t l y , many of the misconceptions are h e l d i n common. Before attempting to impart a concept that would be h e l d i n c o n f l i c t to the student, i t would seem l o g i c a l to help the student r e t h i n k h i s t h e o r i e s by i n c o r p o r a t e c h a l l e n g i n g evidence i n the s c i e n c e l e s s o n -p l a n . The teacher then would be able to b u i l d on a c o r r e c t conceptual framework r a t h e r than i n t r o d u c i n g a f o r e i g n concept that w i l l be i n t e g r a t e d i n t o a f a u l t y framework. If teachers are to u t i l i z e the p o t e n t i a l gained by i n c o r p o r a t i n g new concepts having f i r s t e s t a b l i s h e d a c o r r e c t conceptual base, i t then becomes important to be made aware of the commonalities found i n the misconceptions that c h i l d r e n possess. To do so would e n t a i l a change i s some of the common p r a c t i c e s of the s c i e n c e classroom. The teacher would need t o s t r u c t u r e i n t o the d a i l y a f f a i r s of the classroom a c t i v i t i e s , tasks s i m i l a r to the ones presented. By doing so, students would have o p p o r t u n i t y to v e r b a l i z e t h e i r t h e o r i e s so that the teacher can assess what these misconceptions a re. Such a classroom would need to f o s t e r a s e t of i d e a l s f o r e i g n to " t r a d i t i o n a l ' classroom s e t t i n g . Students' ideas would need t o be welcomed, and t r e a s u r e d as important p i e c e s of i n f o r m a t i o n . The student would need to p e r c e i v e that the ideas he possesses i s of equal value to that of o t h e r s . Such changes would only come about as the teacher imparts the worth of c h i l d r e n ' s 80 t h e o r i e s to them. More time would need to be spent with the stud e n t s , l i s t e n i n g , d i s c u s s i n g , h y p o t h e s i z i n g , and c h a l l e n g i n g them. Of course, such time would be at the expense of other "seemingly' necessary a c t i v i t i e s o u t l i n e d i n the c u r r i c u l u m guides. U l t i m a t e l y , i f classroom a c t i v i t y i s to undergo some of the changes mentioned, i t would a l s o n e c e s s i t a t e change i n many other areas r e l a t e d to classroom i n s t r u c t i o n , such as c u r r i c u l u m development, t e x t book c o n s t r u c t i o n , l a b o r a t o r y a c t i v i t i e s , and other aspects of s c i e n c e education. 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A paper given at the meeting of the A u s t r a l i a n A s s o c i a t i o n f o r Research i n Education, Melbourne, November, 1979. 86 v APPENDIX 87 APPENDIX 1 Sample of a Complete Interview T r a n s c r i p t i o n I: Mary. What I would l i k e you to do i s p i c k up these two b a l l s and t e l l me what you can about those b a l l s . S: T h i s one i s heavy. And t h i s one i s made of wood. And t h i s one i s l i g h t e r than t h i s one. I: Good. I f I were to take t h i s b a l l , w e ' l l c a l l t h i s a ramp, and put i t on the ramp here, and l e t go of the b a l l what would happen? S: I t would go down. I: Why? S: Because i t ' s heavy, i t ' s heavy. I: Because i t ' s heavy what happens? S: I t moves e a s i e r down the ramp. I: I ' l l l e t go and l e t ' s see what happens with the b a l l . Okay.- So what happened? Can you t e l l me what happened? S: I t went down the ramp because i t was heavy enough to move down the ramp. I: Okay. Very good. I f I put t h i s b a l l on the ramp and l e t go of i t , what would happen? S: I t would go down too, but not as s t r o n g as the other. I t ' s l i g h t e r . I: Okay. I t ' s not as s t r o n g , what you mean is..what's another word f o r s t r o n g . S: L i g h t e r . I: I t would gone down l i g h t e r . Would i t reach the end at the same time as the other one? 88 S: No. I: Can you t e l l me why? S: The other one i s h e a v i e r so i s p i c k s up more speed than the l i g h t e r one. I: Okay. So t h i s one would probably move down here slower. Here. Le t ' s l e t go and see what happens. What do you thi n k ? S: I t went down at the same speed I t h i n k . I: What I ' l l do i s . . . There i s a way t h a t you can do t h i s so you can see i f they go down at the same time. I f I l e t go here, and the metal one goes f a s t e r , you should be able to see i t . So why don't you stand up and watch, okay? Go. So what happened? S: The metal one went f a s t e r . I: Very good. Just t r y i n g to put some p i e c e s together, why do you t h i n k the s i l v e r one goes f a s t e r ? S: I t ' s metal. And i t ' s h e a v i e r than the other one. I: Now another q u e s t i o n i s "Why does i t go down on a ramp?" I f I put the b a l l here, why doesn't the b a l l go up? S: Because i t ' s a s l o p e going down. I: So t h i n g s only go down s l o p e s , not up s l o p e s . Why? S: Because i t s s l o p i n g that way and not up. I: L e t ' s pretend f o r a moment that I took the ramp and the two b a l l s to the moon. And I put t h i s b a l l up on the ramp, and I l e t go. What would happen?. S: I t would f l o a t . I: I t would f l o a t , so i t wouldn't go down the ramp? Why i s t h a t ? S: Because the a i r i s d i f f e r e n t . I: Ah. Right. And so because the a i r i s d i f f e r e n t , what happens? S: I t f l o a t s . I: I t j u s t f l o a t s . Okay. And i f I d i d the same t h i n g with the wooden b a l l , what would happen? 89 S: I t would f l o a t too. I: So both of them would j u s t f l o a t . Say I were i n a space c r a f t i n outer space and I took t h i s apparatus, and I put t h i s b a l l on the ramp, i n the space c r a f t i n outer space, what would happen? S: I t would f l o a t . I: R i g h t . And why i s that? S: Because the a i r i s the same i n s i d e as o u t s i d e the space c r a f t . I: So the a i r on the moon, and the a i r on the E a r t h i s d i f f e r e n t . How do you t h i n k i t i s d i f f e r e n t ? S: The g r a v i t y . I: Okay. S: We walk around on the E a r t h , and i f we d i d n ' t have the a i r we would be f l o a t i n g . I: R i g h t . Is there a i r on the moon? S: Well i t ' s r e a l l y heavy. If your i n a heavy s u i t you can walk on the moon. But i f you don't have a heavy o u t f i t you would f l y on the moon. I: So do you t h i n k there i s a i r on the moon? S: Hmmmmm? I: You s a i d i t was d i f f e r e n t a i r . So perhaps t h e r e i s some, or what do you t h i n k ? S: Maybe some a i r . I: C e r t a i n l y d i f f e r e n t . That's very good. You had mentioned g r a v i t y . What i s g r a v i t y ? S: F l o a t i n g i n the a i r . When you f l o a t i n the a i r . I: So g r a v i t y i s what makes you f l o a t ? S: Yuh. I: I t i s n ' t when you f l o a t i n the water though? S: No. 90 I: What I'm going to get you to do i s to w r i t e down on a card what happens when you l e t go of b a l l s on a ramp. We'll pause the camera. We'll l e t you read what you have w r i t t e n about b a l l s on a ramp. S: They r o l l down i t , the ramp. And i f one i s heavy and one i s l i g h t , the h e a v i e r one w i l l go down f a s t e r . On the moon i f the same t h i n g was down the b a l l s would f l o a t i n the a i r because the a i r i s d i f f e r e n t i n space than on e a r t h . I: Very good. Do you want to take a break or should we go on? S: Go on. I: Okay. What were going to do i s work with the same two b a l l s i n a l i t t l e d i f f e r e n t s i t u a t i o n . If I took t h i s b a l l , j u s t r i g h t here, and l e t go of i t , what would happen? S: I t would f a l l . I: Why? S: Because i t can't f l o a t on E a r t h . I: Okay. If i t drops, which way does i t t r a v e l ? S: Down. I: Why doesn't i t t r a v e l up? S: Because u s u a l l y when you drop t h i n g s , they don't go up i n the a i r , they u s u a l l y go down. I: I f I took t h i s b a l l , and l e t go of i t , what would happen? S: I t would go down. I: I t would go down too. And i f I took both of these b a l l s and dropped them at e x a c t l y the same time, what would happen? S: They would both go down at the same speed. I: At e x a c t l y the same speed. Why i s that? S: pause I: These are hard q u e s t i o n s . 91 S: When they go down the ramp they have a s l o p e to p i c k up speed, but when they are dropping they don't have time to p i c k up speed. In the a i r they drop at the same speed. I: What we're going to do i s t e s t t h a t out. I have here a dev i c e c a l l e d a bal1-dropping d e v i c e . When you plu g i t i n , i t turns on an electromagnet. When i t ' s turned on, I p u l l i t back, put the b a l l s i n , and when I press the button i t r e l e a s e s i t . I t drops them at e x a c t l y the same time. I ' l l plug i t i n , and l e t i t f a l l to the ground. What you can do i s stand back and watch i t f a l l . You can a l s o l i s t e n . I put a box here so when i t lands i t makes a n o i s e . And I want you to t e l l me i f they drop at the same speed. Mary, are you i n a p o s i t i o n so that you can see everything? Okay. At the count of three I'm going to c l i c k the button, and you can t e l l me what happens. One, two, t h r e e . So what happened? S: They both f e l l at the same time. I: Do you want me to do that again? S: Yeah. I: I f you l i s t e n , you can t e l l by the sound of i t f a l l i n g . On the count of three. One, oops, one, two, t h r e e . S: They both f e l l at the same time. I: Okay, very good. You've made some very good p r e d i c t i o n s so f a r . Say I went to the moon and I l e t go of the b a l l . What would happen? S: I t would f l o a t away. I: Just f l o a t away. And, so i f I l e t go of both of these b a l l s at the same time, what would happen? S: They would f l o a t . I: They would f l o a t . And i f I took my two b a l l s i n t o the space c r a f t and l e t go of them, what would happen? S: They would f l o a t . I: The reason that they would do that? S: The a i r i s the same i n s i d e the s h i p as o u t s i d e the s h i p . 92 I: Now say I made sure that the a i r i n s i d e the space s h i p were e x a c t l y the same as the a i r on the E a r t h , and then l e t go? S: They would drop. I: They would drop. Would they drop l i k e they d i d on E a r t h where both of them dropped at the same speed? S: Yeah. I: Very good. Okay. What I am going t o get you to do i s to w r i t e down what happens when b a l l s drop, when two b a l l s of d i f f e r e n t weight drop at the same time. We'll pause the camera. MaRry, w i l l you read what you wrote about b a l l s f a l l i n g on the moon, or b a l l s j u s t f a l l i n g i n a i r . S: The l i g h t and heavy o b j e c t s h i t the ground at the same time when dropped because with the ramp the h e a v i e r b a l l has time to p i c k up speed. When dropped, the he a v i e r b a l l doesn't have a s l o p e to help i t p i c k up the speed. When you do t h i s procedure on the moon they w i l l f l o a t because of the a i r . I: Very very good. I don't know i f you want a break y e t . Should we do one more? Super. I have another set of b a l l s here. And I would l i k e you to p i c k them up, and t e l l me what you can about them. S: T h i s one's b l a c k . T h i s one's s i l v e r . And t h i s one's a l i t t l e b i t h e a v i e r than t h i s one. I: Super. I f I took one of the b a l l and l e t go of i t over a f l u i d - f i l l e d tube, what would happen? S: I t would s i n k . I: Why i s that? S: Because i t ' s h e a v i e r and i t would s i n k . I: And i f I took the black one and l e t go of i t above the water, what would happen? S: I t would go down, but i t would go down d i f f e r e n t because i t ' s not h e a v i e r . I: I t won't go down ... pardon me? S: I t wouldn't down as the other o b j e c t because i t ' s h e a v i e r . I: What would you see? 93 S: Sort of f l o a t . I: Okay. So would i t go down slower? S: Yuh. I: Would i t go down as f a r ? S: No. I: How f a r ? S: Maybe i t would go down, but not l i k e the other one, but not as f a s t . I: So mostly, t h i s one would go f a s t e r than the other one. What I ' l l do i s use my bal 1-dropping d e v i c e again. And I ' l l drop both of them at e x a c t l y the same time, l e t ' s see what happens. How's the camera? Are you i n a good p o s i t i o n ? Mary, you can watch r e a l c l o s e l y what happens. On the count of thr e e , one, two, thr e e . Okay. You can t e l l me what happens. S: The h e a v i e r b a l l h i t the bottom f a s t e r than the l i g h t e r one. I: Now t h a t was l i k e what you j u s t p r e d i c t e d wasn't i t ? If I were to do that on the moon, and put the b a l l dropper r i g h t above the w a t e r - f i l l e d tubes, what would happen? S: They would j u s t f l o a t t h e r e . They wouldn't go anywhere. I: And i f I took i t i n my space c r a f t and d i d i t , what ' would happen? S: They wouldn't go down. I: Okay. Very good. I'm t r y i n g to understand why they s i n k i n the water. S: Because the water's p r e t t y l i g h t so i t j u s t goes down. I: Okay. On the moon why doesn't i t do anything? S: Because t h e r e ' s not the a i r f o r c e that goes down. The a i r i s . . . w e l l , the same. I: Right. So the a i r does have something to do with i t . Now, you had mentioned g r a v i t y . G r a v i t y i s an i n t e r e s t i n g t h i n g . You can't see i t , but you can see 94 what i t does. How would you d e s c r i b e to someone who has never heard the word g r a v i t y , how would you d e s c r i b e t o them what g r a v i t y i s ? S: I t ' s the a i r f o r c e that keeps people on the ground. I: Okay. What I'm going to do i s get you to w r i t e e x a c t l y what you s a i d , your d e f i n i t i o n of g r a v i t y . And a l s o I ' l l get you to w r i t e what happens when you drop two o b j e c t s of d i f f e r e n t weight i n a f l u i d - f i l l e d tube. So the camera man can pause f o r a moment. If you c o u l d read what happens when you drop two o b j e c t s i n a f l u i d -f i l l e d tube. S: When you drop two o b j e c t s i n water, one heavy and one l i g h t , the heavy one w i l l go down j u s t a l i t t l e but f a s t e r than the l i g h t one because of the weight i t has. I: You a l s o wrote down your d e f i n i t i o n of g r a v i t y . Could you read t h a t as w e l l ? S: G r a v i t y i s the a i r f o r c e that keep people walking on the ground. I: Just to d i s c u s s t h i s f o r j u s t a l i t t l e b i t . When you're are on the moon t h i n g s f l o a t . A ccording to your d e f i n i t i o n , would there be g r a v i t y on the moon? S: No. I: No. And the reason there i s no g r a v i t y on the moon i s because...? S: There i s no human l i f e on the moon or i n space. So there i s no need to have i t . I: Okay. Say i f I were to go to the pl a n e t Mercury, and i t ' s a hard p l a n e t l i k e the E a r t h . Do you th i n k o b j e c t s would f l o a t i f I l e t go of them? S: Yuh. I: And the reason? S: Because there i s no g r a v i t y out i n space. I: R i g h t . Another s i t u a t i o n . Say I had a huge j a r . And I took a l l of the a i r out of the j a r . So you c a l l i t a vacuum j a r . Then I took my b a l l dropper d e v i c e , and put two b a l l s i n the top, and pushed the button. What would happen? S: They'd f l o a t . 95 I: Why i s that? S: Because there i s no g r a v i t y i n the a i r to keep them dropped. I: Another i n t e r e s t i n g t h i n g . You had p r e d i c t e d that i f you had dropped two b a l l s of d i f f e r e n t weight, that they would f a l l at the same time. And yet when they f a l l i n the water, the h e a v i e r one f a l l s f a s t e r . And you were r i g h t , they d i d . How come t h a t happens? S: Because i t ' s s t o p p i n g i t i n the l i q u i d and not i n the a i r . I: What does the l i q u i d do? S • Wd11• • • • I: How does the l i q u i d make i t f a l l d i f f e r e n t l y ? S: W e l l , h e a v i e r t h i n g s drop f a s t e r i n water. And l i g h t t h i n g s don't r e a l l y drop f a s t i n water. I: What makes them d i f f e r e n t ? S: There's not as much a i r i n the water. I: Okay. So that has an a f f e c t on how they f a l l . Is there anything e l s e you can t e l l me about g r a v i t y ? S: Pause. I: You mentioned i t was the a i r f o r c e that keeps people walking on the ground.. Anything e l s e you know about? Do you t h i n k t h e r e i s g r a v i t y anywhere e l s e i n the univ e r s e ? S: No. I: Where do you t h i n k the g r a v i t y on the E a r t h disappears? In outer space there i s no g r a v i t y . I f you were on a space s h i p from the E a r t h to the moon, somewhere, you say t h i n g s f l o a t i n a space s h i p . How f a r would the space s h i p have to go bef o r e there i s no g r a v i t y ? S: W e l l , you mean out from the Earth? I: R i g h t . S: Maybe the ozone l a y e r . I: Once you're past the ozone l a y e r ? 96 S: Once your past the g r a v i t y around the E a r t h . I: So once your out of the a i r . S: And i n outer space. I: R i g h t . What I would l i k e you to do i s read what you have w r i t t e n on these cards. I'm going to use them as a formal document about your ide a s about o b j e c t s and t h e i r motion. I want you to read and see i f your happy about what you have w r i t t e n . And i f there i s anything you want to change, j u s t n e a t l y c r o s s i t out and add i n what you l i k e . And i f your happy wi t h i t w e ' l l j u s t leave i t . Is t here anything you want to t e l l me about what you learned? S: No. APPENDIX 2 C o r r e l a t i o n of Students' Numbers to T h e i r Names Student # Student's Name 1 John 2 Roy 3 Peter 4 Karen 5 Mary 6 Linda The names used i n t h i s paper have been changed to p r o t e c t the i d e n t i t y of those p a r t i c i p a t i n g i n the study. 

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