March 14 is Pi Day.

On March 14, 1988, a physicist, Larry Shaw, organized the first Pi Day  at the Exploratorium in San Francisco, California.

banana peel

Banana Peel (Photo credit: Wikipedia)

They continue to hold Pi Day celebrations today, marching around a circular space and eating fruit pies.

Now many schools across the country celebrate Pi Day, its date fixed by the closest and most common representation of the number Pi, 3.14, or the Friday before.

Activities shared range from cutting out circles, to bringing in fruit or pizza pies or cookies, to assigning the numbers 0 through 9 a color and stringing beads or paper chains representing the colors of pi, without repeating a pattern. has assembled some of the activities teachers have shared.

They include:

  • Write numbers on index cards and have students string them, in order, down a string in the hallway.
  • Hold a contest for the most number of digits of pi students can recite from memory.
  • Write two digits of pi on each of a number of index cards, shuffle, have students pick out a card and assemble themselves in order of pi
  • Tell stories about pi, like the one about the Roanoke, Virginia teenager who broke the 1979 record in 2006 for most number of digits recited and landed on the Pi World Ranking List

MIT posts its decisions, privately, about applicants for the next year’s class on Pi Day.

Princeton combines its celebration of Pi Day with Albert Einstein’s birthday, also March 14., family-funded non-profit, posts pi-related activities and news, such as their photo of the sky on September 12, 2012, when five sky-writing planes coordinated to write 1,000 digits of pi.

They include a banana measurement activity to illustrate pi.

  • Cut off the bottom of a banana.
  • Cut four slices from the bottom half
  • Peel the four slices
  • Slice open the peel, lengthwise, of the top half of the banana
  • Lay the peel out flat
  • Line up the slices, end to end across the width of the peel

It should be wide enough for three slices, with a little left over.

That’s pi, the ratio of the diameter of the banana, represented by the slices, to the circumference, represented by the laid-open flat banana peel.

Enjoy your banana!

This article first appeared on

Did you ever wonder what pi was, besides a formula you had to memorize?

Did you know your grandchildren might now be celebrating Pi Day?

What was your favorite school holiday?

To you and celebrating the wonder of the world with your grandchildren.


Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers


Enhanced by Zemanta