This study focuses on the interactional processes by which participants make institutionally relevant some ways to take turns in the classroom, which is one of the first places where youth have to respect institutional constraints regarding their interactional practices. These constraints, which are reconfigured online through conversationalists' activities, create expectations in terms of interactional competences notably concerning turn-taking, which is important because of the intrinsic link between opportunities for participation and opportunities for learning. I aim to complement the extensive literature which describes turn-taking in the classroom by focusing on the social knowledge that participants interactionally co-produce to place turn-taking strategies on an institutional value-scale and to agree with the "right" way to take a turn in the classroom, in compulsory and post-compulsory schooling (i.e. do competences deployed at the lower level satisfy those promoted at the upper one?). I propose to apply conversation analysis to the study of social representations. By observing the confrontation between the opportunities for participation proposed by the teacher and how students interpret them, I shed light on the recurrent processes of evaluation that participants co-produce and thus social representations of turn-taking which emerge from them.