A developmental approach to cognitive change in mechanics

This article presents an overview of investigations conducted by the authors to gain a better understanding of difficulties encountered by students in modelling situations to solve problems. By pointing out the differences between students' a priori conceptions and physicists' conceptions, the authors outline a developmental approach to cognitive change in mechanics. The article examines: representations students need to build, as a function of curriculum; precursory representations which help access more canonical representations, and the tasks that elicit these representations; students' cognitive resources which enable them to elaborate new concepts; types of guidance for optimizing the elaboration of these representations. Discussion centres on the usefulness of an epistemological and psychological approach to concept formation in designing learning environments.