It rolls around every year. On March 14, or 3.14, mathematicians, math teachers, puzzlers, physicists, and other math enthusiasts drop everything, put on party hats, and celebrate Pi Day.

Pi, or  p, is a mathematical constant representing the ratio of a circle's circumference to its diameter. As numbers go, it's definitely in a class by itself. It's simple! It's elegant! It's irrational! It's transcendental! With its infinite parade of never-repeating digits marching forever closer to certainty but never quite reaching it, p has captured the imaginations of mathematical thinkers for hundreds of years.

 

Here are some ideas for celebrating Pi Day with students.

 

 

Buffon's Needle is an activity that uses probability to calculate the value of  p. Needles (or hot dogs) are randomly dropped on a piece of paper or other surface marked with parallel lines. The probability that a needle will cross a line is directly related to the value of  p. Click here for a simple simulation of the activity using a Java applet created by George Reese.

 

 

To reinforce the idea that the sequence of digits in p never repeats or ends, have students make beaded necklaces. Each bead color is assigned to a digit, and the necklace is constructed according to the sequence in p. This activity would also work with paper chains. [Diana Funke, Davisville Middle School, Rhode Island]