The didactician as a model within classroom activities: investigating her roles

In this paper we address the issue of teacher professional development, with reference to how to support teachers in activating effective and aware approaches to be adopted during the lessons to foster the students’ use of algebra as a thinking tool. We hypothesize that the didactician, intervening during class activities, could act as a role model for the teacher. We analyse a teaching episode, by means of a combined theoretical framework, to highlight, on one side, the way the didactician acts as a model and, on the other side, moments of achieved harmony between the didactician’s and the teacher’s interventions.