Abstract
The authors show that the knowledge of variables that determine the difficulty of an additive problem differs considerably from one teacher to another. They justify that the roots of these differences are neither in the teaching experience nor teacher education but in the differences in pedagogical beliefs.
Experience is often seen as a source that allows teachers to construct didactical or pedagogical knowledge. The research presented here tries to explore this common belief.
The authors worked with 30 elementary school teachers. They show that the knowledge of variables that determine the difficulty of an additive problem differs considerably from one teacher to another.
They show that neither the teaching experience nor teacher education can account for these differences: thus it must be the differences in pedagogical beliefs that enable to explain these differences in the didactical knowledge.