This chapter describes the synthesis of two powerful approaches to professional development, the Teaching for Robust Understanding (TRU) framework and Lesson Study. The synthesis is known as TRU-Lesson Study.

The TRU framework identifies five essential dimensions of classroom practice: (1) the Content; (2) Cognitive Demand; (3) Equitable Access; (4) Agency, Ownership, and Identity; and (5) Formative Assessment. When classroom practices engage students meaningfully along these five dimensions, students become knowledgeable and resourceful thinkers and problem solvers. In TRU-based professional development, teacher learning communities negotiate their visions of teaching and learning collaboratively by reflecting on artifacts of practice using the TRU framework.

In math-focused Lesson Study (LS), teachers work together to design, teach, and reflect on a lesson that focuses on key mathematical issues and students’ engagement with them. Widespread in Japan, Lesson Study is a powerful mechanism for building and sharing understandings of mathematics content, teaching, and learning.

Teachers in the USA typically have little collective time to reflect on teaching practice. TRU-Lesson Study (TRU-LS) supports the growth of teacher learning communities and their engagement with key ideas and practices of TRU and Lesson Study. Like Lesson Study, it profits from teachers’ concerted attention to lesson design and reflection on the hypotheses reflected in the design. Like TRU-based professional development, it supports teachers to work together explicitly on key dimensions of classroom practice. This paper describes TRU-Lesson Study and provides descriptions of how it plays out in practice.