This page on cooperative Learning has lots of good ideas for groupwork activities that would work in a classroom
This one caught my eye as something to try for maths but there are plenty of others.
7. Team Pair Solo (Kagan)- Students do problems first as a team, then with a partner, and finally on their own. It is designed to motivate students to tackle and succeed at problems which initially are beyond their ability. It is based on a simple notion of mediated learning. Students can do more things with help (mediation) than they can do alone. By allowing them to work on problems they could not do alone, first as a team and then with a partner, they progress to a point they can do alone that which at first they could do only with help.