Ozobot
Tiny Little Robot
Ozobot can identify lines, colors, and codes on both digital surfaces, such as an iPad, or computer screen and physical surfaces, such as paper.
These tiny robots come in a few forms, the Bits model having only wheels and a sensor while the more advanced Evo model has Bluetooth connectivity and programming capability as well.
Using different colored markers users can draw paths for them to follow and give commands such as speed up, turn around, or stop.