r = d / 2

d = 2r

We took circular objects that we found around the classroom and made charts that look like the one below to help us discover how each measurement was related to the others. Before we understood what pi was, we measured the circumference of the objects using string and a ruler.

Le rayon Le diamètre La distance autour (la circonférence)

2.5 cm 5 cm 15.7 cm

5 cm 10 cm 31.4 cm

9.5 cm 19 cm 59.6 cm

Most of us were able to notice that the circumference is almost 3 times the size of the diameter. This was a pretty cool realization, because then we were introduced to the irrational number π (pi). This led us to discover one more formula: C = π d

This is pretty abstract Math, so some of us had a hard time applying the formulas when solving problems at first, but we are all starting to get the hang of it now. We will be celebrating Pi Day on March 14 (3/14 - the last day before Spring Break), so feel free to bring a nut-free pie of some kind to share with the class!