Background: This study is the second study of a design-based research, organised around four studies, that aims to improve student learning, teaching skills and teacher training concerning the design-based learning approach called Learning by Design (LBD). Purpose: LBD uses the context of design challenges to learn, among other things, science. Previous research shows that this approach to subject integration is quite successful but provides little profit on (scientific) concept learning. For this, a lack of (knowledge of) proper teaching strategies is suggested as an important reason. This study explores these strategies and more specific the interaction with concept learning. Sample: Six Dutch first-year bachelor’s degree science student teachers, between the ages of 16 and 18, and two science teacher trainers (principal investigators included) were involved. Design and methods: A mixed methods study was used to study LBD’s teaching practice in depth. Based on a theoretical framework of (concept) learning-related teaching strategies video recordings of a guided LBD challenge were analysed to unravel teacher handling in detail. Complemented by questionnaire and interview data and students’ learning outcomes (pre- and post-exam) the effectiveness of teaching strategies was established and shortcomings were distracted. Results: Students reached medium overall learning gains where the highest gains were strongly task-related. Teacher handling was dominated by providing feedback and stimulating collaboration and only 13% of all teacher interventions concerned direct explication of underlying science. And especially these explicit teaching strategies were highly appreciated by students to learn about science. Conclusions: In accordance with insights about knowledge transfer, LBD needs to be enriched with explicit teaching strategies, interludes according to poor-related science content important for cohesive understanding and de- and recontextualisation of concepts for deeper understanding.@en