A Case Study of Middle School Science Teachers` Topic-Specific Pedagogical Content Knowledge on the Unit of Stars and Universe

Pedagogical Content Knowledge (PCK) is intrinsically domain/topic-specific knowledge for teachers` expertise. On the basis of this idea about PCK, we investigated in-service science teachers` topic-specific PCK on the unit of stars and universe in terms of teachers` knowledge and practices. We observed four middle school science teachers` classes for eighth graders, and took the videos of the classes. The topics of the classes covered constellation, annual parallax and the distance of stars, and the expansion of the universe. We also examined the teachers` pedagogical thinking through video stimulated recall interviews. In addition, we developed a protocol to analyze the levels of participant teachers` PCK and the characteristics revealed in their classes on each topic. Results of the study showed that the participant teachers` level of PCK varied across the topics of classes and the sub-components of PCK. We also identified teaching orientations played key roles in shaping overall characteristics of their PCK. Moreover, astronomical thinking such as spatial thinking and system thinking, was not appropriately embedded as the specific practices into the astronomical concepts in their instructions. We discussed the implications on the progressions of teachers` PCK in terms of their professional development.