Context: In 2022, Berlin`s regional teacher training institution started a voluntary course in blended learning for vocational schools under the academic supervision of Humboldt University. Approach: This course was developed and evaluated as a design-based research project according to the general model by McKenney & Reeves, with a special focus on knowledge types according to their epistemic categories (cf. Goldkuhl) and knowledge forms according to their materialisation and explication (cf. Johanneson & Perjons). Results: The results are both pragmatic and theoretical insights on blended learning in vocational schools, manifested in a “Navigator” for the final course design and a “Knowledge Map” for its epistemic categories. Conclusion: The authors conclude that the conceptual factors of progression and supervision, accompanied by their respective competences, are fundamental differentiating factors in developing a distinct blended learning competence in vocational education.