Résumé
Fine-grained methods studying knowledge in transition proceed habitually by interaction analysis in small groups of students. But how could we investigate processes underlying conceptual change in large-group situations, in which most of students just attend and may encounter mind wandering or attention lapses?We focused on large group but rather participative situations: we studied collective debriefings of role-playing activities in teacher education. We used “course of action” method from ergonomics in which “self-confrontation” interview technique aimed at accessing not only to the manifest experiences of students who were participating in interacting but also to the silent experiences of those just attending these interactions. Data were analyzed by indentifying units of experience, and then conceptual distinction and relations in these units. Afterwards we assessed the alignment of the conceptual experiences of each student on those of the teacher.Results showed that the participation of the students in the debriefings may not reflect their alignment on the conceptual elements the teacher intended to present. Therefore the teachers have to avoid a “participative illusion” regarding the conceptual understanding in such large-group situation.