They’re mysterious. They’re ominous. They’re elusive. Those circles are impossible to track down. Ok, well maybe not really. Circles are actually all over the place. Almost everywhere you turn you can find a circle. Take a look at the clock. It’s a circle. A basketball hoop? Circle. Traffic Lights? Circles. The home button on an iPad, iPhone, or iPod. Again, a circle. They’re everywhere. And every single one of those circles has it’s own radius, diameter, circumference, and area.

We had just started to learn previously about radius, diameter, and circumference. Now, this week, we also learned how to find the area of a circle!

To find the area of a cirlce, the first thing you need to do is find your radius. Then, you’re going to square your radius. That means if your radius is 3 inches, you’ll do 3 x 3. Finally, you’ll multiply that by pi which is about 3.14. 3 x 3 is 9 and 9 x 3.14 is 28.26. So the area of a circle with a radius of 3 inches would be 28.26 inches squared (don’t forget to write squared just like any other time you find the area).

In order to help us practice finding the radius, diameter, circumference, and area, we had our Circle Hunt. The way it worked was that we had 6 circles located in various places around the school. Students worked in groups of 3 and each group had one of the iPods that were donated to us on Donors Choose. On every piece of paper was a different sized circle and a QR code. A QR code is essentially a barcode that can display a website, dial a phone number, or display text. In the case of our circle hunt, when each QR code was scanned with an iPod, it displayed a clue to where the next circle was located.

Each student had a worksheet that they brought around with them so they could fill out the information about each circle. They began at circle 1, finding the radius. Once they measured the radius, they scanned the QR code which gave the message, “The curtains have drawn and it’s time for a show. It’s now off to circle number 2 you must go.” Students then went and found circle 2 on stage in our auditorium. They continued on until they had located all the circles and had measured the radius of each. Once complete, the group returned back to the classroom to then figure out the diameter, circumference, and area based upon the size of the radius!

Based upon the work done in class, everyone’s understanding all the parts of a circle quite well. Based upon the slideshow below, it looked like everyone had a wonderful time!

What are some other things in math you may use a formula for?

Can you name the formulas for how to find radius, diameter, circumference, and area?