This document introduces key terms related to circles such as radius, diameter, and circumference. It defines a radius as the distance from the center to the edge of a circle, diameter as a line that passes through the center and spans both sides of a circle, and circumference as the distance around the edge of a circle. Examples are provided to illustrate radius and diameter, and it is noted that the diameter is always twice the length of the radius.

1. Introduction to Circles
Radius, Diameter, and Circumference
Objective: Student will learn about circles.

2. Definitions
The distance from the center to the edge.
The diameter starts at one side of the circle, goes
through center and ends on the other side.
The Circumference is the distance around the edge of the circle.

3. Introduction to Circles
Radius, Diameter, and Circumference
What is a radius?
The Radius is the distance from the center to the edge.
Is this a radius?
All are examples of radius.

4. Introduction to Circles
Radius, Diameter, and Circumference
What is the radius for this example?
5 mm

5. Introduction to Circles
Radius, Diameter, and Circumference
What is the diameter for this example?
Diameter= 2 x radius
Diameter = 2 x 5mm
5 mm
10mm

6. The end

7. The end