Most STEM education reforms aim to prepare learners to use science in their post-school daily lives. This goal is not about content – reproducing correct science facts is not sufficient to solve practical problems of real people. However, even in classes structured by reformed curricula, students are often permitted to construct knowledge only insofar as it aligns with canon. Here, we argue that the tension between reproducing “correct” ideas and constructing one’s own ideas is exacerbated by - and partially arises from - our approach to designing and refining curricula. Through exploration of a design-based research project, we illustrate our field’s habit of optimizing curricula to better support students’ construction of canon-aligned answers. Our field would be better served, we argue, if design and refinement of curricula was driven by ideas about knowing and learning science (i.e., epistemologies) manifest in curricular enactments. Such epistemologically responsive design-based research would potentially move activities structured by curricula toward activities students might encounter in post-school life. We present an ongoing project in our group as an example of what epistemologically responsive design-based research might look like. We then conclude by articulating practical and theoretical implications of designing and refining curricula on the basis of students’ epistemologies.