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

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 ?