Arrow keys move the cat to the colored blocks. If your Raspberry Pi is set up correctly, the lights will come on when the cat touches that color. Obviously, to get the full effect, you have to have a Raspberry Pi (they're only $35! GO GET ONE!) three wire jumpers, three resisters, and three LEDs. A breadboard (like the one in the Canakit Ultimate set) is a good idea too.
Demo of using Scratch to control three LEDs connected to the Raspberry Pi.Make sure you look at the script in the stage too ;) Wiring layout picture thanks to Fritzing (fritzing.org to download). Modifications to original code: added the START broadcast so I can show the fritzing diagram of the circuit for this project.
