In their exploration of students’ experiences of a flipped classroom calculus course, Voigt et al. (2019) designed and implemented a classroom teaching experiment. The authors claimed that their methodology was one type of design experiment (which they call “design-based research”). Using Cobb et al.’s (2003) description of design experiments, critique Voigt et al. (2019) study and propose an alternative version of this study to meet the requirements of design experiment research.