Lesson Study is a professional development tool originating from Japan, through which teachers systematically examine their practices with the goal of becoming more effective. This examination centers on teachers working collaboratively on a small number of "study lessons." Working on these study lessons involves planning, teaching, observing and critiquing the lessons. To provide focus and direction to this work, the teachers select an overarching goal and related research question that they want to explore. This research question then serves to guide their work on all the study lessons.
While working on a study lesson, teachers jointly draw up a detailed plan for the lesson, which one of the teachers uses to teach the lesson in a real classroom (as other group members observe the lesson). The group then comes together to discuss its observations of the lesson. Often, the group revises the lesson and another teacher implements it in a second classroom, while group members again look on. The group will come together again to discuss the observed instruction. Finally, the teachers produce a report on what their study lessons have taught them, particularly with respect to their research question.