International audienceThis article aims to discuss how the theory of didactical situations in mathematics (TDS) can be used to answer research questions concerning regular teaching practices, production of resources for regular teaching, and teacher development. In the first part we focus on TDS and the way it may be a tool for the researcher to understand teaching practices and the way it may contribute to develop teaching practices, helping teachers identify questions useful for their practice. In the second part, we present analyses using TDS in two contexts in which researchers worked with teachers, making explicit or not the concepts they used. The third part approaches, from these two contexts, the way TDS may help the collaboration b...