Since most kids have already mastered the art of iPad password cracking and in-app purchasing, we should probably give them something productive to do. The arduino-based Vortex from DFRobot is a STEM-reinforcing plaything that can help kids learn to code. It comes with preinstalled programs, so you can have fun racing, bumping and spinning right out of the box, but the variations are endless. Open-source hardware and the WhenDo app's graphical programming interface mean the sky's the limit with Vortex. These little bots are laden with proximity and ground sensors, LEDs and speakers — not to mention all the optional add-ons — to help bring them to life. DFRobot has given us a pair of two-robot packs for a couple lucky Engadget readers this week. All you need to do is head to the Rafflecopter widget below for up to three chances at winning this hackable robot duo.