Bazinga - an awesome review game for most any subject and any grade. Students are in teams, I ask questions, and the students answers them. If a team is correct they have the chance to pick a Bazinga Card and we do what it says (e.g. double your score, erase 1 point from another team, switch the team captain of the winning team with the team captain of the losing team, etc.).
While students are working problems, walk around the room with a handful of green pens. When someone finishes the problems correctly, they get a green star and a green pen. Now they are qualified to coach and star papers for other students, and so on, until everyone is done.