YOUR TAX-DEDUCTIBLE CONTRIBUTION PURCHASES THIS ITEM FOR OCS - THANK YOU! Algebra BalanceUnlike any other balance, the Algebra Balance lets you demonstrate that 1<0. Weights placed on the outer pans represent negative integers, and those placed in the inner pans represent positive integers, making it possible to demonstrate that (1)+(+1)=0. Great for small-group work, the balance comes with 4 plastic pans, 4 plastic canisters, a set of plastic weights and a Teaching Guide.