The purpose of this study is to examine how teachers' PCK is expressed in a Science teaching practice, both from a teacher and a student perspective. The study is a qualitative study of three teachers' physics classroom lectures in grades 7-8. International research highlights the teacher's impact on students' achievement in general and in science education in particular and there are several ongoing projects that investigate these components of this impact. This study investigates how teachers describe and reflect on their teaching actions while teaching physics and how these actions are experienced by the students. The study uses the concept, Pedagogical Content Knowledge (PCK) as a perspective on teacher knowledge. In the study, lessons were prepared in a collegial collaboration using the conceptual tool Content Representation (CoRe). The lessons were conducted, video-recorded and reflected through stimulated recall interviews in video clubs with both teachers and students. Teachers and students watched the video-recordings in the video club settings which were also video-recorded and transcribed for further analysis. The results shows how the implicit PCK was made explicit in video clubs. The dialectic process between teaching and learning was made visible to the teachers and led to a professional development and an extended understanding of the students response to the teachers´ actions.