Today, I learned about another simple machine. However, only some people classify it as one. I am talking about the gear. The gears purpose is to change the direction on the force. There are three types of gears: a worm drive, a spur gear, and a spiral bevel gear. Whenever a gear is used, the other gear it is attached to will always rotate an opposite direction. Gears have been used for thousands of years, the earliest being Antikythera Mechanism, which had over 30 gears and one of the earliest astronomical machines. In my opinion, the gear is just a gear and axle. Tomorrow, I will learn even more about gears!