We tackle the issue of how teachers can be led to acquire conceptions and models of behaviours suitable to foster among pupils a linguistic approach to the algebra since primary school and in particular to develop in them modelling, interpretation and thought production skills. We propose a model of structured task, as a connected set of questions addressed to teachers and centred at the analysis of activities and pupils’ productions as well as on the design of classroom discussions for a collective sharing of related results. This task is made of operative and critical reflection activities, aimed at favouring the development of predictive and interpretive thinking by teachers, with respect to pupils’ behaviours. The structure, made of enchained scenes, induces teachers to question and review their convictions about their own role in the classroom and to become aware of the dynamic processes involved in the social construction of knowledge