Engaging students in design has great potential for promoting learning in science education, and design practices have been gaining emphasis in national science curricula in recent years. In the actual success of this type of instruction, teachers play a key role. Many recommended teaching practices for design-based science education hinge on teachers’ attention to what and how students are learning as they are engaged in design. Gaining insight in student learning in the course of instruction means that teachers have the opportunity to tailor their actions to students’ learning needs, and enhance student learning during a learning process. While previous research showed that teachers’ attention to student learning differs between types of instruction, characterisations of teacher attention in secondary school, design-based science settings remained scarce. Attending to student learning has, nevertheless, been posited as particularly important yet complex in design-based classrooms due to design’s multifaceted and open-ended nature. The reform-based character of design-based science education further contributes to this complexity, which also pertains to design-based chemistry education. Chemistry has, however, seldom been featured in design-based education research, despite design’s central role in the chemistry discipline, and in chemistry curricula...@en