Content knowledge and pedagogical content knowledge in Taiwanese and German mathematics teachers

• We assessed teachers' content knowledge and pedagogical content knowledge by tests.
• For these tests, previous studies showed predictive validity for student outcomes.
• The structure of subject matter knowledge was cross-culturally invariant.
• German and Taiwanese teachers' CK and PCK reflected differences in teacher education.
• CK and PCK in teacher subgroups reflected teacher selection processes.

In comparing content knowledge (CK) and pedagogical content knowledge (PCK) of Taiwanese and German inservice mathematics teachers, the present study examines whether the two-dimensional structure of teachers' subject matter knowledge is cross-culturally invariant and whether differences in teacher education and in teacher selection are reflected in teachers' subject matter knowledge. The results confirm that CK and PCK represent two distinct, but correlated dimensions, even in teachers from completely different backgrounds. Taiwanese inservice teachers showed considerably higher CK and also higher PCK scores than German teachers. Teacher education and teacher selection should be considered important levers for reform in mathematics education.