Circle as a shape

A circle is the set of all points in the plane that are a fixed distance from a fixed point. 

Objectives

Understanding circle as a shape

Estimated Time

30 minutes

Prerequisites/Instructions, prior preparations, if any

Prior knowledge of point, lines, angles, polygons

Materials/ Resources needed

• Digital : Computer, geogebra application, projector.
• Non digital : Worksheet and pencil
• Geogebra files : Introduction to circles.ggb 

Download this geogebra file from this link.

Process (How to do the activity)

• Draw circle with ‘circle with center and point’ or use the slider
• What do you notice, how is the circle formed.
• Which point is the centre of the circle ?
• Plotting points on the circle, connect these points to the centre of the circle.
• What can you say about the segment lengths?
• Measure the segment lengths to show they are equal.
• Establish center of the circle’ and ‘radius’
• Differentiate between circle and region enclosed by a circle.

• Evaluation:

1. By what parameter is the size of a circle defined ?
2. Bigger the radius, _____________
3. How do you name a circle ?
4. Can you draw a circle without knowing the radius ?