CooperativeGames.com

This is a game that involves     sequencing. It can be adapted to decimals, fractions, integers,     etc. Give each student a large card with a number on it. They     self-assemble in numerical order without talking. For more fun,     have kids play against a timer so they have to scramble quickly     into line. A fun variation is to play this with positive and     negative integers such that pairs of kids choose to be the     positive and negative side of 1, 2, 3, etc. Kids should catch on     quickly that they need to position themselves symmetrically     around the “0” card to build a number line of all the integers.
(This game was developed by Suzanne Lyons, founder CooperativeGames.com)

This game is suitable for upper elementary school through high school. You can play it with any math topic. Prepare a sheet of problems of varying difficulty. Place a sheet on each desk in the room. Play music and let students work on the problems individually. Now stop the music and collect half the sheets. Turn the music on again, and let students work in pairs on the remaining sheets. When the time is right, turn off the music, and collect half the sheets again so that students work on the remaining problems in groups of four. Finally, play the music again and let students finish the assignment in groups of four. The teacher scores the exercise by counting the total correct answers on all the sheets collected through all the rounds so the group scores best when everyone works fast or when kids who can solve the hard problems focus on them. After your class tries this once or twice, they will figure out strategies to maximize the overall group score.
(This game was developed by Suzanne Lyons, founder CooperativeGames.com)

Pass around a hat containing various math problems on a strip of paper. Provide two copies of each problem. Papers with the same problem should be both labeled as 1, 2, 3 etc. to make it easy for students with the same problem to find each other. Students pair up and solve their problem together. When they have completed the problem, they become the “teachers” of it. Now pairs of students join to make cooperative groups of four students. The “teachers” teach the problem to the “students”—their partners who haven’t yet worked the problem.
(This game was developed by Suzanne Lyons, founder CooperativeGames.com)