4. Example 1 - Circumference of a circle - continued

• Discuss that if we had the tools to measure our circles very accurately we’d find that the circumference is actually 3.14159… times larger than the diameter and that we short-hand this number using the Greek symbol (spelled pi, pronounced “pie”).

So our formula becomes C = x D.

• It’s a given that nearly every learner in your class will have seen, heard and/or used the formula for calculating circumference sometime before you go through this activity.

For many though, has always just been a button on their calculator or a symbol that we replace with 3.14 in the formula. By taking them through this activity, they can see the meaning of and realise that it was born due to the nature of circles, not, as is commonly concluded, that circles are born of .

• Most importantly, the learner should see that in every circle the circumference should be roughly 3 times the diameter so they have a meaningful check for whether their answer looks reasonable when using the formula.