Calculate the Circumference of a Circle Using Pi

In this activity, you will asked to complete different questions all about circles.

A circle is a 2D shape where every point on a circle has the same fixed distance from the centre.

In Year 6, we learn about the parts of a circle.

Let's recap:

Diameter

This circle shows the diameter. This is the length of the line through the centre, from one edge to the other.

Radius

This circle shows the radius. The radius is the distance from the centre of the circle to the outer edge.

The radius is half of the diameter so is fairly straightforward to calculate.

Circumference

A circle's circumference is the distance around the edge.

How to find the circumference of a circle

To find the circumference of a circle we have to use the formula:

(2 x  x r)

 = pi = 3.14

Example

So, let's find the circumference of this circle.

The radius is 5 cm.

(2 x 3.14 x 5) = 

(6.28 x 5) = 31.4

The circumference is 31.4 cm

Your turn!