How can kids move a ball into a target with 2 high walls from 2 feet away? Build a ramp? A catapult? A trampoline? A zip-line? There are no right answers and we provide no solutions--it's up to kids to use ZOOB pieces (and other materials that they choose) to build contraptions that solve the challenges. The ZOOB Challenge features 175 ZOOB pieces, string, wheels, a ball, rubber bands, a foam play pad, and 25 challenges based on STEM (Science, Technology, Engineering, & Math) skills-skills that educators have targeted as essential to helping the US compete successfully in the 21st century.