Wheel
From Wikipedia, a free encyclopedia written in simple English for easy reading.
A wheel is a disc- or circle-shaped mechanical device. Its main purpose is to allow things to roll; in other words, the wheel spins, and objects on the wheels move more easily along the ground. It is a simple machine.
[edit] History
Most experts believe the ancient Mesopotamians invented the wheel about 4000 BC. In addition, the Chinese rediscovered it around 2800 BC. The Incans and Maya had wheels on children's toys around 1500 BC, but they did not use wheels for work. Sub-saharan Africa and Australia did not have the wheel until people there met people from other cultures.