Abstract
We present in this paper an experiment involving two theoretical frameworks: the Anthropological Theory of the Didactic (ATD) and the Didactic and Philosophical Approach in Mathematics (DPAM), applied to a group of pre-service secondary school mathematics teachers in France in the context of a course in didactics and epistemology of mathematics on the introduction of literal calculus. The results obtained suggest the methodological and didactic relevance of this mixed approach and underline the illusion of transparency of the variable among teacher students, who for most of them didn’t identify the obstacles related to the indeterminate in teaching-learning situations.