This article aims to explore the bilingual practices (English and French) used by students from St Martin in a collaborative situation, in order to enrich the debate on languages and knowledge. This research is based on two corpora consisting of interactions between high school pupils during their educational support sessions, and which are studied using conversational analysis; the study uses this combination of collaborative methods and bilingual education to model the management of linguistic resources with regard to the factual knowledge and practical skills brought into play during the interaction. The challenge of this study is therefore to establish what is involved, and under which conditions and through which mechanisms the interactions between two languages (English and French) may contribute to the construction of cognitive learning skills.