# Introduction of Circles/ Discovering Pi

In this lesson, we will discuss vocabulary associated with circles (radius, diameter, circumference), which most students should be familiar with, and discuss why the formulas similar to what we used with polygons for area and perimeter won’t work with circles (circles don’t have sides, aren’t polygons). Once that discussion is over, I will introduce Pi and ask if any students have heard of it (not the kind you eat!) and tell them it’s the “magic” number when it comes to circles. We will then do the activity, which is the main part of today’s class.