The purpose of this study is to examine how teachers' PCK is expressed in science teaching practice, both from a teacher's and a student's perspective. It is a qualitative study of three teachers' physics classroom lectures in grades 7 and 8. International research has highlighted the impact of teachers on students' achievement in general and in science education in particular, and several ongoing projects are investigating the components of this impact. The present 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 of pedagogical content knowledge (PCK) as a perspective on teacher knowledge. In the study, lessons were prepared in a collegial collaboration using the content representation (CoRe) conceptual tool. 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 show 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. [For the complete volume, "Bridging Research and Practice in Science Education: Selected Papers from the ESERA 2017 Conference. Contributions from Science Education Research. Volume 6," see ED615249.]