1: It took 1,000 years to prove pi irrational.
2: The first people to refer to the ratio between the diameter and circumference of a circle were the Ancient Egyptians.
3: "I prefer pi" is a palindrome.
4: Albert Einstein was born on Pi Day, 1879.
5: 22/7 is sometimes used to estimate pi.
6: The first major Pi Day celebration was in 1988.
7: Pi has been calculated past the two quadrillionth digit.
8: P and pi are both the 16th letters in their alphabets.
9: You can likely find your phone number in pi. Here's the site that searches for it: http://angio.net/pi/. I found mine!
10: And the one that completely blows my mind: 3.14 backwards is PIE!
There is also this metric version.
And here is a Pi Day pennant for younger kids with less challenging circle problems any yummy fun-to-color pies. When the pennants are solved and colored, they can be hung along a string in your classroom to celebrate!
My friend Julia from Teacher Julia's Resources sent me this great photos of her students' Pi Day mobiles hanging from their classroom ceiling. Here's another photo from her classroom:
I bundled all 3 of the activities in this post (plus the metric version of the Pi Day pennant) here: Pi Day Activities Bundle.
Happy Pi Day!