Power Functions (19 parts)
Power Functions is a system for connecting LEGO electronics to battery packs which was used from 2007-2018.
Power Functions is typically used for simple machines which connect to a battery pack and are simply turned on and off.
The LEGO Education WeDo 1.0 set allows you to control simple robots using parts with a Power Functions connector. A program running on a computer can respond to sensors and control lights or motors. (The program is streaming over USB.)
