Pi Day

Yesterday, we celebrated "Pi Day." Since the number "pi" is rounded to 3.14, Pi Day occurs on 3/14, or March 14th. Of course, my husband explained that geeks invented Pi Day, but since most of us in this family likely fit into the "geek" category, that works for us!

Even though my kids are a bit young to fully understand the concept of pi, I decided to celebrate it anyway. Early in the day, I made a big deal out of the date, relating it to the concept of pi. Because of that, Hannah and Ben now easily associate pi with the number 3.14, although we had to work on saying "three point one four" instead of "three slash one four" like the date. They also can explain that we round to 3.14 because pi goes on forever without repeating in a pattern.

For fun, I introduced the parts of a circle: circumference, diameter, and radius. I showed them my coffee mug and used a ruler to measure the diameter. Using that number and the calculator Ben requested for Christmas, we multiplied pi times the diameter to find the circumference. "Hmmm...," I wondered aloud, looking at the ruler, "How can we check our answer?" Ben jumped up and down excitedly. "I know! I know!" he exclaimed. He ran upstairs to his room, returning in a moment with his tape measure. I grinned. "Perfect!" I told him. We measured the circumference of the mug, and the kids squealed happily when they saw that the answer was correct.

Next, I showed how to calculate the circumference of a two-inch circle on paper, including explaining to Hannah how to multiply 3.14 x 2 without using the calculator. When I saw that Hannah and Ben both seemed to grasp the concepts, I decided to attempt a slightly more difficult problem. "OK," I told them, "Tonight, I am going to make quiche for dinner. Quiche is a kind of egg pie. So we will have pie for Pi Day!" After the cheers subsided, I went on, "I make my quiche in a 9-inch pie pan. Why don't we try to calculate the circumference of the pie?" I drew a diagram of the pie on a piece of paper, and I had them tell me how to find the circumference - pi x 9. Now, Hannah understands the concept of multiplication, that 4 x 9 is the same as 9+9+9+9, but she hasn't yet memorized the facts or covered multiplication in her math curriculum. Amazingly, I wrote out 3.14 x 9 and demonstrated how to multiply 4 x 9 and carry the 3, and Hannah finished the problem herself!

Since this portion of the lesson went so well, I also briefly touched on the area of a circle and how to calculate that as well. We used the calculator to figure out the area of the pie and learned the difference between inches and square inches. Then, I turned the kids lose with the rulers, tape measure, and calculator and let them experiment with what they had learned. Surprisingly, I think they learned a lot, even though the topic is a bit beyond their current level in math.

Finally, for dinner, I did make a delicious quiche, and the kids told Josh all about their lesson, while happily eating their Pi Day pie! Today, Ben wrote this in his journal:

"Yesterday was pi day and we ate pie for dinner"

Overall, I think Pi Day turned out to be quite a success!