<small groups trying to teach themselves seems like an invitation to b.s. sessions about who is dating who and how many Hideo struck out last night against the Rockies. At least it would be entertaining!> If you read the literature on cooperative learning, I believe you would find that cooperative learning sessions need to be designed so constructive work takes place. It is not an excuse for teachers not to plan, but rather to plan better on how to engage the students in their learning. Someone stated they can tell if the students are "getting it" when they are lecturing. When I am observing in classes, I frequently sit in the back of the room and I was amazed at how little many of the students were listening and what other things they were doing - in fact, I've seen students talking about who is dating etc. while the teacher was lecturing. Sometimes the conversations are by note, but sometimes they just chat with one another. I think even more important that cooperative learning, which I think should be used judiciously, should be whole group response strategies. Having the students involved in the lesson is what's important. have them solve a problem as you're talking. Then have them share their answer with a neighbor and see if they agree. Have them share their solutions with another pair and voila, you have a cooperative group. I think you have to have quiet think time - discussion time with other young mathematicians - time to defend your ideas and time to hear the pearls of wisdom from the teacher. All these components are important, but the most important is to have the student connected. Do they feel they can explain what you are talking about or can they just sit back and mindlessly copy down your words into their notes. I vote for involvement.