Robotics is a vast, thrilling, and sometimes overwhelming interdisciplinary field involving physics, engineering, and computer science. This kit gives kids a simple, fun, and customizable introduction to robotics that lets them build eight motorized machines controlled by programs and an ultrasound sensor. Kids code the programs using an easy, visual programming app on a tablet or smartphone, which connects to the robot models via a wireless Bluetooth connection. The ultrasonic sensor works on the same principle as sonar. It sends out sound waves, which bounce off objects. The sensor interprets the echoes returning to it, and from this detects objects in the path of the sensor. Using the app interface, you can program the robots you build to behave based on the feedback coming from the ultrasound sensor. Build a humanoid robot that walks forward on two legs and pivots to avoid obstacles in its path. An awesome stag beetle model moves backwards or forwards in response to an obstacle, and opens and closes its pincers. Construct a funny crocodile model that wags its tail if no object is in sight, but then opens its giant jaws when an object approaches. Using an additional smartphone and tablet, you can even hack together a cute little spy-bot that roams around and streams video back to the tablet screen. A cool dual-rotor drone model rotates its rotor blades 90 degrees. You can also assemble other fun robots including a robo-dog and robo-dino. After you have learned how the technology works, you can build and program your own robots using the kit's 230 building pieces.