1. The wheel is one of humanity's oldest inventions. The very first wheels were created over 5,000 years ago in ancient Mesopotamia (modern-day Iraq).

2. The first wheels were not used for transportation. Instead of pulling carts, the earliest wheels were actually potter's wheels used to shape clay into bowls and pots!

3. Wheels made moving heavy things much easier. Before wheels, people had to drag heavy loads on sleds or pull them over logs. Wheels reduced friction, allowing one person to move weights that used to take dozens of people to drag.

4. Wheels need axles to work. A wheel by itself just rolls away! It took hundreds of years after the wheel was invented for people to figure out how to connect a solid rod—called an axle—through the center so a platform could rest on top.

5. Early car tires were bright white. Natural rubber is white, so the very first tires were white too. Makers later added a carbon powder to the rubber to make tires stronger and last longer, which turned them black.

6. The largest wheel in the world is a Ferris wheel. The Ain Dubai in the United Arab Emirates stands over 820 feet (250 meters) tall—that's taller than two football fields stood end-to-end!

7. Wheels are hidden inside almost every machine. You use wheels every day without knowing it! Gears inside clocks, rollers inside computer mice, and pulleys inside elevators are all different types of wheels.