I was talking with my "math specialist" friend the other day, and she mentioned that she went to the NCSM meeting in Atlanta and heard something interesting. One gentleman was doing preliminary work on class size and found that some higher performing schools had up to 40 students per math class. Can you imagine? And, they seemed to do better by whatever scale they measured these things by.
His theory was that with 40 students in a class, the teacher does not have the time/resources to help each kid individually, so the kids are forced to fend for themselves and help each other out, and the process of this involves them talking math to each other and forming their own knowledge and this in turn makes them retain things better.
Either that, or maybe it's a sink or swim situation. Maybe the kids that are discipline problems or such somehow are weeded out. I don't know. But the talking it out theory gives me something to think about even though I don't have THAT many students in class.