I may be wrong. However, many years ago when I studied educational anthropology, I was told, and not too long ago observed for myself, that the Japanese classroom is very homogenous. Even so, one does not find 50 students in rows. In elementary school they work in cooperative groups called hans.
I would never compare Japanese education to our education. There are many cultural differences. Even in Japan, there is a cry for smaller class sizes.
High school tracking is the norm. If you are interested in looking further into Japanese education, I suggest you look at Japan's High Schools by Thomas P. Rohlen or The Japanese Junior High School: A view from the Inside by Paul S. George, Evan George and Tadahiko Abiko, published by the National Middle School Association..
As for research about class size, there has been some done. I know that within the last 8 years the Journal for Research in Mathematics Education, NCTM, has published research. --
Math History Lives!
Karen Dee Michalowicz VQUEST Math Lead Teacher/Trainer Upper School Mathematics Chair Virginia Quality Education The Langley School in Sciences and Technology 1411 Balls Hill Rd, McLean, VA 22012 USA 703-356-1920(w) E-Mail: firstname.lastname@example.org Fax: (703) 790-9712 --or-- KarenDM@aol.com