These interactive cards let kids work on their own to master measurement! Designed for use with our Lakeshore Smart Pencil (sold separately below), the illustrated cards and programmed activity cartridge target skills like comparing heights and lengths. Students just slide the cartridge into the pencil, then press it to a card to begin a voice-guided activity—with easy-to-follow cues, positive reinforcement and instant feedback! Set includes 40 cards and an activity cartridge; cards measure 4" x 6".