ABSTRACT
This chapter analyzes how students’ mistakes can productively inform instructional decisions made during lesson study, and how teachers have gained insight into student thinking by carefully analyzing those mistakes. I examined a case of lesson study in which teachers learned about the value of open-ended activities through examining student mistakes. As teachers reflected on instructional decisions they had made for the research lesson, they gained a new appreciation for inclusive teaching and student mistakes. This examination shows that lesson study is a perfect setting to reconsider what mistakes are and how to use them to make sense of student thinking and possible partial understanding of students. In order to surface such understanding in the lesson, inclusive and open-ended activities are essential, and teachers need to discuss common mistakes students make or typical challenges they experience with the lesson topics and focus on both correct and incorrect strategies
