Young thinkers can build unbelievable ball track structures with this simple stacking plank system. Create ramps, funnels, chutes, and crazy contraptions like the "Black hole" and "Bounce plate." then find out if the ball rolls as expected. Fostering unlimited creativity and experimentation, Keva planks build an early understanding of proportion and balance, while teaching basic principles of physics and engineering. No glue, no connectors-just loads of constructive fun! Contraptions planks are made from pine.