For contemporary teaching, teachers need good knowledge of pedagogy, content, subject methodology and assessment. Although subject didactics have become an independent research area with interdisciplinary dimensions, few studies focus on the teaching of subject didactics. With the aim of developing a theoretical model for the systematic treatment of subject didactics, a scoping literature review was carried out to analyse the scientific literature. Twenty-five articles were chosen from different databases in the field of study. Data analyses revealed three domains of subject didactics: content knowledge, pedagogical content knowledge and knowledge of subject-specific assessment. These domains included various components which were used for developing a theoretical model for teaching subject didactics within the framework of primary teacher education. The results indicated how to organise university courses on subject didactics for primary teachers. First, teachers' content knowledge and pedagogical knowledge should be treated in an integrated way. Second, integrating pedagogical knowledge with subject didactics enables teacher education to be shaped so that students understand the teaching profession at an early stage. Third, studying subject didactics on both a theoretical and empirical level is the driving force for developing syllabi in primary teacher education.