As stated earlier, the purpose of this proposed Discussion Group is to facilitate discussion and initiate collaborative research with colleagues around the world to seek effective ways to improve teacher professional development through Lesson Study. Lesson Study was introduced to the US mathematics education community in the 1990s (Yoshida, 1999; Lewis, 1993; Lewis & Tsuchida, 1998; Stigler & Hiebert,1999) and gradually spread among researchers and educators in the US and subsequently around the world. Although research suggests that professional development like Lesson Study should be an ideal approach to help teachers acquire mathematical knowledge and develop skills for teaching mathematics, only a few effective implementations of Lesson Study have been reported.
There are at least two possible impediments to the effective implementation of lesson study. First, Lesson Study is a cultural activity among Japanese teachers and schools, and is not easy to replicate in schools in other cultural settings. Secondly, although the process of Lesson Study has been described based on the careful observations of Japanese teachers’ activities, the mechanism by which Lesson Study improves teaching may not be fully understood. As a result, implementations often mimic superficial features of Lesson Study without having much impact on overall teaching. In order to overcome this dilemma and establish a systematic professional development program among schools in different situations, there is a need for discussion among researchers and educators in order to exchange knowledge and expertise about innovative professional development approaches such as Lesson Study.

The key questions to be addressed by this proposed Discussion Group are:
A. What are the key elements of Lesson Study that can help teachers gain mathematical knowledge for teaching?
B. What are the key elements of Lesson Study that can help teachers develop expertise in teaching mathematics effectively?
C. How can an established effective professional development model such as Lesson Study be translated for use in different cultures?
D. How can a professional development model such as Lesson Study be adapted for use in pre-service teacher education?