Defining within a dynamic geometry environment: notes from the classroom

This paper concerns the activity of defining. We report about an experiment in which we studied students\u2019 behavior in constructing and classifying quadrilaterals within a dynamic geometry environment (Cabri-G\ue9om\ue8tre). In particular, we considered the problem of the consistence of certain definitions with the constructions made with Cabri, i.e. we used the microworld to make students reflect on the adequacy (within the microworld) of the definition they use. The findings show that there are kinds of thinking that are developed as a result of the interaction with the tool and suggest considerations on the problem of providing students with a meaningful and active approach to theoretical thinking