Jerry Albani has identified an important aspect of group dynamics when he writes:
<<<I also feel that Cooperative learning is not for everyone at all times. Several of my students had to be allowed to continue to work by themselves in a group setting until they felt comfortable and ready to join the group. I found that by respecting their right to go it alone permitted them to eventually become active group participants -- and at the end of the year, even they extolled the merits of groups in allowing people and them to help each other and discuss ideas.>>>
I have found that they strength and positive nature of group learning and activities is so strong that it eventually draws all students into the process. When they see others actually having fun discussing and debating and even arguing about mathematical solutions and approaches they get interested in what is going on. When they also see that they are in a safe environment to make mistakes and that analysis of mistakes helps everyone instead of penalizing them they begin to open up. I find that most people do not want to participate out of fear of looking foolish or worse stupid. Jerry's other point about respecting peoples right to chose their learning approach is very important. If we want students to behave responsibly and act like adults then we need to trust their judgement. Especially with adolesents who like to exert their independence, you will not be able to force them into a group approach. Keep in mind that there is an individual accountability with group work so the students who persist in working alone still has an opportunity to demonstrate that they have mastered the material. Sometimes you can encourage hold outs through a reward or bonus process for the group work assigned, something that does not directly penalize the student working alone. Some other aspects of group work that encourages loaners includes their being able to get extra help in class from their peers and the teacher, they see other students developing a very positive relationship with the teacher, that the teacher cares about each student and gets to know everyone on a personal basis, and in some cases they try helping others and get a big lift out of it when they find that can indeed tutor other instead of always being tutored. I often hear squeels of delight (literally) when people who have been math phobic all their lives suddenly realize that they are actually teaching someone else math. I get little chills when that happens even though I am expecting it. One final note: Not everyone participates 100% of the time every day. I have students who are having a bad day or have other pressures on them who you can tell are not involved on a particular day. They will usually tell you if you ask them (individually, not in front of the class) and by accepting their honesty you gain their confidence. I had a student once who literally dragged into class one day. I asked her how she was doing and she replied that she was totally distracted with another course and probably wouldn't be able to learn much in algebra. I suggested she go to the library to finish her research and I would work with her later if she needed help. Later many other students commented in a writing assignment on that interaction very positively, that I respected her feelings and situation. It just seemed very logical to me.