For any circle, of any size, the distance around that circle divided by the distance across that circle equals 3.14159. . . pi is an irrational number, so that precise decimal continues infinitely without ever repeating itself.
In 1988, Larry Shaw defined March 14th as Pi Day, and suggested ways to celebrate it. Within a few years, many Math teachers heard of his ideas and jumped into leading Pi Day Parties. Teachers were thinking, "Since 3.14 is a common approximation for Pi, why don't we celebrate "Pi Day" with our students on March 14th? The goal was simple: help kids remember that fabulous, fun, irrational number Pi. We called it a a success if the only thing a student remembered from a Pi Day celebration was:
(Lazy grammar is purposeful in the below quote. This captures what most teenagers would actually say, months after our Pi Day celebration, if someone asked them “What is Pi?”)
“Well, one day in March, my Math teacher acted really excited, and, like, we played some Math games, and then ate pie. In class! I got chocolate. It was pretty cool. So, I guess since March is the 3rd month . . .well, I guess, like, Pi must equal 3-point-something, because . . .well, she said that the party day was the Pi number and . . . like I don’t remember the date, ya know? So I don’t remember the decimal or anything but I guess 3-point-something must be what Pi is.”
If our teenage students could say “Math class was fun today” AND get locked into their brain that “Pi is about 3”—we called that a success!