Today is March 14, which corresponds to the first three digits of Pi. Because pi is 3.14159….some schools hold their celebrations until 1:59.

Pi is called an irrational number; it has an infinite number of digits: 3.1415926535 8979323846 2643383279 5028841971 6939937510 5820974944 5923078164 0628620899 8628034825 3421170679…First 100 digits of Pi

Pi is the ratio of any circle’s circumference to its diameter. In other words Pi is the number you get when you divide the circumference of a circle (the distance around the circle) by its diameter (the distance across). It is typically written as 3.14.

March 14th also happens to be the birth date of Albert Einstein—which makes it a double math celebration. You can watch NOVA‘s “Einstein Revealed,” which exposes the hidden life of Albert Einstein and traces the birth of his groundbreaking ideas. See it at: http://to.pbs.org/15OBsMm

**A brief history of Pi: ***by Rhonda Cratty*

- Ancient Babylonians determined the area of a circle by taking 3 times the square of its radius, which gave the value of pi, 4,000 years ago. One Babylonian tablet found, revealed a value of 3.125 for pi, which is a closer estimate.
- In 1706, William Jones began using The Greek letter π.
- Euler made the symbol popular in 1737.
- 1761, Lambert proved that Pi was irrational; it cannot be written as a ratio of integer numbers.
- In 1882, Lindeman proved that Pi was transcendental, that is, that Pi is not the root of any algebraic equation with rational coefficients. This discovery proved that you cannot “square a circle”, which was a problem that occupied many mathematicians up to that time.

**My Favorite Activity to celebrate Pi Day:**

***Read an excerpt from the book Life of Pi. I like to read Chapter 56 on fear since math is often fearful for students (and others of us!). Here is a post which spotlights just Chapter 56.

**O****ther Activities to celebrate Pi day: ***by Rhonda Cratty*

- Who can memorize and recite Pi to the most digits without a mistake!
- Read a variety of stories involving the use of measuring circles.
- Read about ancient Egypt and Archimedes
- Measure the circumference, diameter and radius of objects around the house.
- Only eat circular food.
- Create your own Pi T shirts using Fabric Paint or Fabric Markers
- Pi Bracelets, with each bead color representing a number
- Make a pizza measuring the circumference, diameter and radius.
- For dessert, of course, you must have pie!

Look for other Pi activities at the following websites: http://www.homegrownhearts.com/piday.htm http://www.education-world.com/a_lesson/lesson/lesson335.shtml http://www.exploratorium.edu/pi/ http://www.teachpi.org/activities.htm