The concept of equivalence in a socially constructed language in a primary school class

We analyze two episodes of a teaching experiment involving children of primary school. The children, handling a procedural language they previously constructed, single out equivalence rules. So they construct the concept of equivalence intuiting a semantic equivalence in the language. We adopt a qualitative approach mainly based on observational and ethnographic methods. We present a data analysis regarding how the children, in interaction, co-construct the solutions to the tasks, according to the activity theory and the epistemological triangle.