Mots clés : Dispositifs, TPE, PPCP, structuration, posture.

Summary This work focuses on the new devices that have been introduced in the French curriculum in high schools as well as vocational schools these last years: TPE (individual student initiated projects) and PPCP (pluridisciplinary projects of a professional nature). The article focuses first on these devices and more precisely on the students' intellectual processes ofprogressively structuring their knowledge and then the new teaching practices teachers develop to guide such progressions. We distinguished several levels ofstructuring and, studying several cases, we showed the students' evolution. We also detected the 'attitudes'the teachers adopt for their new roles.