Attempts to develop a global discussion about the roles of dynamic geometry systems (DGS) by addressing four points: (1) the variety of possible contexts for proof in a DGS; (2) the dual nature of proof (cognitive and social) as reflected in the "milieu" constructed around the use of a DGS; (3) from observing to proving; and (4) overcoming the…

Described are problems of the teacher's management of computer use during the learning process and student acquisition of new knowledge that can be transferred to situations outside the software environment. Choices made to address these problems are illustrated as students learn axial symmetry using the microworld Cabri-gomtre. (MDH)