This is an annual conference for US teachers. Lots of professional development opportunities and a chance to look at teaching materials and manipulatives at the Exposition. Next year it will be at San Diago, California (www.nctm.org/meetings) 21-24 April 2010.
There were 828 sessions in all! Plenty to choose from. There were some on lesson study in mathematics too. Akihiko Takahashi did one on What We Learn Through Lesson Study: Ideas to Design Lessons for All. I went to the lecture by Deborah Ball and she proposed this idea on teachers' horizon knowledge and how it can be developed. I suppose lesson study can help teachers develop this knowledge which essentially is knowledge that allows them to understand where the mathematics their students learn will lead them to.
Jane Gorman presented a session on Starting Lesson Study at Your School.
I went to the National Research Council Report on Early Mathematics (Doug Clements, Karen Fuson, Sybilla Beckman & Herbert Ginsburg) to get some ideas as I will be working more and more with the kindergartens. In the evening I went to a session that got us solving primary school problems - quite fun if you like solving mathematics problems. I was presenting on the second day - two presentations - so I doubt I will have a chance to attend any sessions.
Other than Takahashi, the other people from the APEC Lesson Study group who were there were Patsy Wang, Lim Chap Sam, Makoto Yoshida and myself.