Children put STEM into action with our hands-on challenge kit! This engaging kit includes 5 challenge cards to prompt kids as they plan, create and test toy spinning tops. Children stack layers of disks to build the tops—and discover how balance and weight change the way the tops spin! Kit includes 4 wood spindles in 2 different heights, 14 plastic disks in various shapes, a spinning tray, 5 challenge cards and an activity card. Large spindle measures 4" high.