Codic alternation in class interactions of French as a foreign language: the qualifying secondary cycle. This article is a reflection on the teaching/learning of French as a foreign language in the qualifying secondary cycle in Morocco, and more specifically on class interactions. Our observation is that language practices are affected by the coexistence of French with several languages in particular dialectal arabic. The alternation of these two linguistic codes is very present in the context of the teaching of French. In this perspective, this contribution, which gives great importance to the field and in which the corpus takes precedence aims to examine interactions in a French class. To do this, it aims to quantify, on the hand, the turns of speech expressed only in French or in dialectal arabic, and on the other hand, those where it is question of alternation of codes, and also to find the factors that cause these shifts between the mother tongue and the target language.