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UBC Theses and Dissertations

Operational structures applied by children to problems related to predator-prey interaction in ecology and the beliefs held about this phenomenon : a comparison with Inhelder and Piaget’s study of the hydraulic press problem Kargbo, Dennis Borboh


The general aim of the study was to investigate children's thinking about ecological systems involving interactions between predator and prey populations in a food chain. Specifically the study was directed at (a) comparing and contrasting the mental operations which children applied to problems involving predator-prey interaction in a food chain and mechanical equilibrium, and (b) identifying typical beliefs or misconceptions which children may hold with respect to food chains. Empirical and non empirical methods were adopted to execute the study. The non empirical aspect involved advancing logical arguments to support the hypothesis that predator-prey interaction involves a principle of action and reaction which is similar to that underlying mechanical equilibrium. Piaget's (1953) symbolic notation was employed to substantiate the arguments in this part of the study. The empirical aspect involved interviewing forty elementary and secondary school children, of age range 6.0 to 15.11 years, using a simulation of a food chain made up of populations of hawks, snakes, frogs, grasshoppers and grass The simulation was presented using a cardboard model in conjunction with a microcomputer program. The length of the interview for each child averaged 30 minutes. During the interview the child assumed the role of a cattle farmer and was required to predict the effects on the herd of cattle should changes happen in the food chain. The questions asked were specifically directed at assessing the subjects' ability or inability to apply the equilibrium operations of Identity, Reciprocity, Inversion and Correlate (Inhelder and Piaget 1958) to the predator-prey problem. A few other questions were directed at assessing the subjects ability or inability to apply probability to the food chain problem. The data recorded on audiotapes were analysed with the use of Piagetian tabular and descriptive methods. The results confirm the hypotheses advanced that the subjects in the predator-prey study would: (i) exhibit developmental patterns that were similar to those exhibited by subjects of Inhelder and Piaget (1958) in the mechanical equilibrium study (ii) exhibit misconceptions that were specific to the food chain task. On the basis of the results it was reported that the understanding of interactions between predator and prey populations required formal thinking. This type of thinking was first observed at the age of 12 years in this study. This indicates that most elementary school children do not possess cognitive structures to deal with food chain problems in a formal way. Consequently it was recommended that curriculum developers and teachers postpone the introduction of food chain ecology until about the age of 12. Finally it was suggested that since predator-prey interaction is similar to mechanical equilibrium at both the transformational and operational levels, the two topics could be taught in school under the umbrella of action and reaction systems.

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