Assembly
These labs can be used by a wide variety of Arduino kits. The kits should have two DC hobby motors and a motor controller such as the L293C controller that allows you to control a motor with a PWM signal.
For many CoderDojo projects we have designed a low cost robot that is described next.
$25 Robot Platform for Teaching Programming¶
This robot is built around a standard "Smart Car" chassis that you can get on eBay for around $12. It also contains a low-cost motor controller, an Arduino Nano, a ping sensor and a breadboard that allows you to expand the kit in many different ways.
The assembly of the robot is documented here