Our Four -PAN ALGEBRA BALANCE will make a perfect addition to your math manipulatives! Unlike any other algebra balance, this balance will make it possible to physically show -10. Weights placed on the outer algebra balance pans represent negative integers and those placed in the inner pans represent positive integers. Place a weight in each pan on one side of the center post and the algebra balance remains level as (-1) + (+1) = 0. This algebra math manipulative is perfect for small group work. The balance comes with four plastic pans, four plastic canisters, a set of plastic weights and a Teacher's Booklet. Minimal assembly required. Ages 11 to 17