Students solve addition problems hands on—with colorful building bricks! Kids just select an activity card, stack bricks on a building base to work out the problems, and then write their answers right on the card. Plus, the cards are self-checking—with answers on back. The kit has enough materials for up to 4 students at once, including 160 bricks, 4 building bases, 20 different write & wipe cards and a guide. Cards measure 7" x 9". Write & wipe markers sold separately.