Young thinkers can build unbelievable ball tracks with this simple, stacking plank system. Create ramps, funnels, chutes and crazy structures. Then find out if the ball rolls as expected. Fostering creativity and experimentation, KEVA planks build an early understanding of proportion and balance, while teaching basic principles of physics and engineering. No glue or connectors, just loads of constructive fun! Includes 2 lightweight balls and an instruction book with ideas. Contraptions planks are made from pine. Ages 7 and up.