Story and Activity for Pi Day from PBS Parents

Pi, it’s irrational! It goes on forever! It also thoroughly mystified me growing up. What is Pi? Why do we need it? This March 14, go on a math adventure with your kids to solve the mystery of Pi.

You’ll Need


    Read Sir Cumference and the Dragon of Pi with your kids. We found a copy at our local library. It’s not only a great story, it’s a clever way to help kids understand Pi. In the story, Sir Cumference drinks a potion that accidentally turns him into a dragon. His son, Radius, must find a cure. Along the way, he meets Geo and Sym Metry, brothers who make wheels and helps his cousin, Lady Fingers bake pies and solves the mystery of Pi.

    Pi activity for Pi Day on March 14

    Now have the kids try what Radius did in the story. Take a piece of string and measure the diameter (d) of one of their favorite round snacks. We used an orange.

    In the story, Radius took equal lengths of pie crust to create a wheel. The spokes reached across the pie fine, but when he tried to create the outside circle of the wheel, three wouldn’t fit. There was a gap.

    Diameter and circumference activity to celebrate Pi Day

    Now, have the kids carefully triple the length of string. Essentially, they’re multiplying the diameter by three. Cut the string.

    Activity for pi day

    Try to wrap the string around the outside of the orange (or whatever food you used). It won’t reach all the way around; there’s a gap. That gap is why we need Pi. It’s that .14159265359… that we need for our string to reach all the way around.

    Understanding Pi - Pi day activity

    So this Pi day, celebrate Pi along with all things round and irrational, like pie for breakfast. Okay, maybe that’s not exactly irrational, but it is delicious. Happy March 14!

    P.S>. Did you know that March 14 is also Albert Einstein’s birthday? Happy Birthday Al!

    More Adventures In Learning

About Jennifer Cooper

Jennifer Cooper

Jennifer Cooper is the blogger behind, an online resource for creative families.  Her favorite past times include: dancing around her living room, watching the Pink Panther with her kids and daydreaming. She lives in Baltimore, MD with her husband, photographer Dave Cooper, and two children. 

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