The purpose of this study was to characterise the development of a preservice physical education teacher's professional activity over the course of training interactions with her co-operating teacher. The student teacher's professional development was studied using a hermeneutic and inductive approach based on the analysis of data from observation and self-confrontation interviews. The results showed that the preservice teacher's conceptions regarding her teaching developed despite communication difficulties with her co-operating teacher and that she constructed new knowledge--at times without her co-operating teacher's awareness--even when she disagreed with him. However, the student teacher's classroom activity did not always change as a result of this new knowledge. The self-confrontation interviews revealed her construction of knowledge, as well as the reasons for disagreement and her resistance to changing her classroom action.