The research-project Co[superscript 2]CA investigates the influence of teacher-trainings on in-service teachers' expertise. Within a teacher-training-study 27 in-service teachers have been trained in selected ideas about teaching, having an exemplary focus on central aspects of formative assessment in competency-oriented mathematics. At the end of the teacher-trainings the teachers' pedagogical content knowledge as crucial aspect of teachers' expertise has been evaluated by using tests being sensitive to the teacher-trainings. Results of this evaluation point out: Within teacher-trainings pedagogical content knowledge can be conveyed to in-service teachers successfully. [For the complete proceedings, see ED597799.]