Computational thinking is a key competence for children to learn in today’s digitized world. In order to effectively teach computational thinking, elementary science teachers need to have appropriate professional knowledge, consisting of content as well as pedagogical content knowledge and pedagogical knowledge [15]. This research project will adapt the Computational Thinking Test (CTt) to assess German pre-service teachers’ content knowledge in the area of computational thinking, and develop corresponding items based on case vignettes to assess pedagogical content knowledge.