Maybe I'm slow, and you've all seen this sort of thing in action already, but my afternoon precalc class was a blast to watch in action today. I have 9 groups of 4, and gave each group a different word problem from the book. These were problems that needed the use of Law of Sines or Law of Cosines.
They were to solve the problem and be ready to be the experts on it when others asked them for help. I helped the groups who needed help, and as groups were getting close to done, I told each group their next problem, and who their personal experts were. I loved seeing one person walk over to another group to get help for their group. I loved how hard they all worked. It was great.
My morning class doesn't seem to get as engaged as this class, though. I'm trying to dream up a way to pull them in.