Blix RobotixGearbox Kit

There's no better way to learn than hands-on learning. If you want to teach your kids the concept of how a gearbox works, this is an excellent kit.

You can configure the "car" to have a high gear ratio to demonstrate high torque and low speed; or low gear ratio to demonstrate low torque and high speed. The pieces connect easily like Lego and there are many more things you can do with this kit so this makes for a great gift for an older kid or young teen.