Basic elements of a circle

Investigation to understand basic parameters associated with circles.

Objectives
To recognize different terms related to circles

Estimated Time
40 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, compass, strings
 * Geogebra	files : Elements	of circles.ggb

Process (How to do the activity)
Use geogebra file:
 * Connect a point on	the circle and the center of the circle. Rotate to show line	segment measures the same – establish radius
 * Extend the radius	from center of the circle to meet the circle.
 * What is the	measure of the line segment connecting the two points on the circle?
 * Establish concept	of diameter
 * What is the	difference between the radius and diameter?
 * How are they	related?
 * What	will happen if any two points on a circle are joined.

Hands on activity
 * Placing a point on	the circle, can I measure the length along of the circle starting	from this point to ending at the same point.
 * Measure the	circumference using distance	tool.
 * Will the	circumference change if radius is	changed. How are circumference and	radius related.
 * Draw	a circle with a compass, mark 5 points on the circle. Join the these	points to the center of the circle. Take a thread and measure the	segment length. Record the data in the table.

For the circles drawn above measure the circumference using the thread to note the values. Also note your observations

Draw a circle. Draw a line from any point on the circle passing through the center of the circle to intersect at another point on the circle. Mark the segment. Repeat the same taking different points on the circle. Note your observations