The Unifix Operations Tray is a great tool for demonstrating addition and subtraction problems. To demonstrate addition, fill the slots on each side with Unifix Cubes and then combine the cubes into one channel to see the results. For subtraction, first fill one side and then move some of the cubes to the other side to demonstrate subtraction. Includes activity ideas. Tray measures 14 1/2″ x 2 1/2″. Packaged in a clear bag with header card. Grades K-2.