Difficulty level: challenging Build it: use the 172 building pieces to construct your own adorable robotic pet Hedgehog! Manufacturered by Thames & Kosmos. Sound-activated: the robot has a built-in sound sensor allowing your Hedgehog to react to different patterns of claps. Get rolling: your Hedgehog is programmed to tumble roll spin around Bristle its spines and scurry along in response to your claps-clapp once and your Hedgehog curls up into a ball and tumbles backwards one time. Clap multiple times and it will roll again and again tumbling once for each clap! Build time: 1 to 2 hours S. T. E. M. Learning: by building your pet you'll gain experience in the inner mechanical workings that enable the Hedgehog to move the way it does; learn about gears motors sound sensors LEDs (your hedgehog's eyes light up! ) and more! Battery-operated: your funny little pet Hedgehog comes with a motor that requires (4) AAA batteries (not included).