This video explores Pi by throwing darts at a dartboard. Pi can be calculated using a random sample of darts thrown at a square and circle target. The problem with this method lies in attempting to throw "randomly."
Kumon has a collection of activities that you can try out with your students on Pi Day. Make necklaces, learn about hat sizes, have a scavenger hunt or word challenge.
This activity was created for parents but could easily be applied to a lower elementary classroom. It involves Sir Cumference and the Dragon of Pi and round snacks.
This experiment attempts to convert the first 10,000 digits of pi into a musical sequence. Choose 10 notes on the keyboard; each will represent an integer. The computer cycles through the digits of pi, creating corresponding notes.