In the framework of a cooperation project that aims to identify the competencies required for teaching computer science in schools, we are developing a conceptualization of PCK currently. Up to now, we have derived a category system from literature and evaluated several interviews with teaching persons. In this paper, we describe the category system and the most important steps of its derivation. Further, we present the results of a survey that had investigated all curricula for CS teacher education that we had found in Germany, looking for the implementation of those categories. Furthermore, we are preparing interviews among experts about PCK, applying the Critical Incident Technique.