In the previous section you designed and explored wheels in Tinkercad. These wheels may look like a perfect circle, but they are not. The edges are made up of small line segments. You can see this better if you use the Tire shape in Tinkercad. Here are some shapes made with the Tires shape to help you explore math about circles.

If you can print out this page:

- Draw a more perfect circle around the edge of each tire. Use your pencil and string.
- Draw lines on each circle to show the radius and the diameter.

In this picture, the bold lines on the *Workplane* are **1 unit apart**.

- Estimate the length of the diameter and radius for each circle.
- Small circle: Radius______ Diameter______
- Medium circle: Radius______ Diameter______
- Large circle: Radius______ Diameter______

- What is the relationship between the radius and the diameter of each circle?
- The diameter is ______times the radius.

- Is that true for any circle?___Talk about it: Why do you think so?