I'm not a fan of group projects. When people say that students need to learn to work together on a task, or that many heads are better than one, I point out that when that happens in the workplace there's an assumption that everyone brings something to the table. I think we all know that isn't necessarily the case in the K-12 classroom.
We're getting new curriculum and textbooks in stats this coming year, so I'm not sure if I'll do the same projects that I've done in the past. For the ones I have assigned, though, part of the reason I do it is because the data collection, analysis, and report would be a lot of work for just one student. One other group project I assign, I admit I use groups because I don't want to read 90 reports--I'm not an English teacher. All the bosses and accreditation folks want to see cooperative learning/group work, though, so that's what I give them--just not very much, because I'm not convinced it's all that useful in most circumstances.
I don't like it for the same reason that students don't like it:
As for group projects, “the smartest kids do all the work because the grade matters to them,” students say. Slackers slack.
One achiever told Downey he’d always dreaded group assignments or labs until he took nothing but advanced classes his senior year. “When you work with someone who wants the A as much as you do, group projects can be pretty fun,” he said.