Nothing like planning and reflecting together to build trust: studies on teams of practicing mathematics teachers' and coaches' collaboration

Lesson Study, which originated in Japan, is viewed around the world as an effective platform for teacher collaboration and professional learning. However, relatively little is understood about the theoretical underpinning of teachers' collaboration and their professional learning. This chapter seeks to explore to what extent the diversity of the different teachers' experience and knowledge in a cross-school planning team, including the observers and outside experts, contribute to deep levels of discussion and reflection in the context of Lesson Study. The findings reveal that together with the cross-school structure of the teams, the diversity of the planning team contributed to minimize the impact of power relations.