The powerful role of prior experiences and cultural schemata in guiding novice teachers' conceptions of how to teach is hardly contested. We report on a "reflective practicum" at the very beginning of a pre-service teacher education course that interconnects prior beliefs, reflection-in-action and reflection-on-action and that, in principle, models a complete reflection cycle. Peer-teaching activities zoom in on the extent to which prior ideas about good teaching may be shared: rooted in cultural metaphors that can be made more analytically transparent. Triangulation and peer scaffolding across institutional roles yield an emerging awareness that conventions for doing interaction are sensitive to local conditions that can be systematically explored. The students reframe and refine their initial ideas about good teaching in terms of questions about practices in authentic classroom situations, thus creating a bridge between theory and practice. We conclude that detailed observation and more sophisticated analytical tools are needed to trace how learning and reflection are discursively constructed in the moment-by-moment shifting participation formats of institutional interactions.