Interaction of modalities in CABRI: A case study

In this paper we consider an experiment in which 15 years old students explore a phenomenon of covariance, by using Cabri for drawing geometric figures, measuring, and sketching graphs. In this way they collect different types of information. A first research question is how students deal with them in situations of exploration, in particular, which role they ascribe to the numerical data. Another research question is how students approach formal aspects. The activity on which the experiment is based is a telling example of how Cabri enlarges the scope of the exploration, in a way that could not be possible in paper & pencil environment.