Every year on January 22, people around the country celebrate their love for pie (apple pie anyone?). Why not make this a fun day to teach your students about pi, the ratio of a circle's diameter to its circumference? Pi, or π, is an irrational and transcendental number, meaning that its decimal numbers continue infinitely without repeating.

So use today as an excuse to not only enjoy a delicious slice of your favorite pie, but to celebrate the number pi! Here are three activities we're sure your students will enjoy:

1. Host a pi party! What National Pie Day celebration is complete without pie? Make your celebration feel more like a party with pizza and pie, but have your students work for their slice. Show students how pi can be important in everyday thinking by having them work in groups to determine which size pizza would be the best value for their money or how big each slice of pie should be so that everyone gets an equal slice.
2. Bring in pictures books. Many teachers suggest reading students the picture books Sir Cumference and the Dragon of Pi or Sir Cumference and the First Round Table to introduce or reinforce important mathematical concepts like pi, diameter, and circumference. The books, which are written by Cindy Neuschwander and Wayne Geehan, are part of the Sir Cumference Math Adventure series and are a great tool for bridging math and reading. Although the books are marketed toward kids as young as six, teachers of both elementary and middle school students have shared that their students love these books and better understand math as a result of reading them. 
3. Teach a rap song. In 2004, a Wall Street Investment Banker created a parody of Eminem’s hit song "Lose Yourself" in which he raps about "the agony and thrill of getting up on stage and trying, under extreme pressure, to recite the digits of pi." Pi Diddy, his math-rapper alter ego, has since performed "Lose Yourself (In the Digits)" for hundreds of students from 5th grade to college, and the song has become a popular way to capture students’ attention and teach them about pi. "Lose Yourself (In the Digits)" is available for free download at teachpi.org.