Lesson Plan: Circles

This lesson plan is for introducing a 6th grade class to circles. First ask students what a circle is.  Show them pictures and images of circles on the overhead as students explain.  They'll try to describe it, but usually say what it is not or that it is round or other vague descriptions.

Next, draw a point in the middle of your white board. Then, take a ruler and have students come up one at a time to draw a point anywhere on the board that it 12 inches away from your point (for a smaller class have them each draw 2 or 3 points). The students will start to see that the points form a circle.  Continue this process until you have enough points away from the center where you can see that the points can be joined to form a circle.  Have the last student join the points. Then ask again, using what you just did, what is a circle? They will try to describe what they see, and you can help them refine what they say into a definition: a circle is a set of points that are the same distance away from a given point (called the center of the circle).

From here you define the radius as that distance from the given point (center) to any  point on the circle, and the diameter as the distance from one point on the circle to another going through the center. Then you can use the circle the students made to talk about the circumference of a circle with a 12 inch radius.  This lesson plan will give students a deeper understanding of the definition of a circle by discovering what a circle is for themselves.  It puts a lot more meaning into the definition when students can make the connection between how a circle is made (from making points equidistant from the center in every direction) and how it is defined.