Apprendere la matematica con gli strumenti: il ruolo di mediazione dell’insegnante.

Recognizing the relevance of the construction of knowledge by the learners, a complex educational problem concerns the movement from individual activities towards sharing and institutionalizing mathematical knowledge. Teacher’s role is crucial: how to manage the movement from a task to the evoked mathematics? We face this problem in the specific case of tasks involving digital tools; we focus our attention on the actions performed by teachers while orchestrating collective discussion, on the effects of such actions on the evolution of mathematical meaning discussed, and on the sharing of those meanings between the students. A single case study exemplifies the presented theoretical framework to show how, through the chosen lenses, we can evidence teacher’s actions during the collective discussion