“…Teachers' PD relates to all different facets of professional competences (Roesken-Winter, Schüler et al, 2015). It includes teachers' content knowledge (knowledge about the subject, CK), pedagogical content knowledge (knowledge about how to teach the subject, PCK) and pedagogical knowledge (general pedagogical knowledge, PK) (Shulman, 1986), teachers' classroom practice (Clarke & Hollingsworth, 2002;Zehetmeier & Krainer, 2011) as well as teachers' beliefs, their relatively long-standing subject knowledge of certain objects and the attitudes linked to that knowledge (Pehkonen & Törner, 1996), teachers' motivation; and teachers' competence in self-reflection (Baumert & Kunter, 2013).…”