Lesson study is a TPD model originating in Japan (Fernandez & Yoshida, 2004; Takahashi & Yoshida, 2004). A central feature of lesson study is konaikenshu, which means in-school (konai) training (kenshu) (Fernandez & Yoshida, 2004). According to Fernandez and Yoshida (2004), “in school training” differs from what we imagine in American schools, in that it brings together the entire teaching staff of a school for hours to collaborate on an agreed-on school goal and action plan. In a lesson study approach, teachers conduct cycles of inquiry to ultimately facilitate student learning. The PD in this study consequently committed to a year of structured activities, reflection, and support via partnerships, large-group discussions, and instructional coaches. Quantitative and qualitative evidence that Lesson Study has positive effects on teacher learning outcomes has been documented in existing research (e.g., Cajkler et al., 2014; Coenders & Verhoef, 2019; Vermunt et al., 2019)