Pi = approximately 3.14 or 3.14159, to be more accurate. Most people can memorize this number fairly easily.

We've put together this bulletin board idea you can use to help your students understand the concept of Pi. Add a piece of laminated plastic below the question on the board and let your students write a few more digits each day to show the numerals that make up Pi (as many as your students can fit on the board or down the wall). Click here to download the bulletin board pattern and instructions from the Excel Math website.

The Egyptians and the Babylonians knew about the existence of the constant ratio pi, although they didn't know its value nearly as accurately as we do today. They had figured out that it was a little bigger than 3. The Babylonians had a more accurate approximation of 3 1/8 (3.125) than did the Egyptians. Read more about pi at the Math Forum at Drexel University.

Pi is the ratio of the circumference of a circle to its diameter. Pi is always the same number, no matter what size circle you use to compute it.

It's the longer (and even more accurate) numerals that are harder to recall:

You can use a computer to calculate pi. If you'd like to see pi carried out to 10,000 digits, visit the University of Utah's website.

The area of a circle is pi times the square of the length of the radius, or "pi r squared":

A = pi*r^2

You can use your imagination to create additional bulletin boards and murals for your classroom using pie charts, pictures of pie divided into fractional parts, and images of the mathematical constant pi.

LaVern Christianson, a teacher in Minnesota, even wrote some Pi Day songs for his students. One of my personal favorites is "Happy Pi Day to You." You might want to plan a Pi Day celebration for your students to help them remember this special number. They could write their own songs and poems, see how much of the number Pi they can fit in a three-inch square on a piece of paper, draw pictures of what comes to mind when they hear the word infinity, solve a brainteaser, and enjoy some Pi-related snacks.

New to Excel Math? Take a look at elementary math lessons that really work for Kindergarten through Sixth Grade on our website: www.excelmath.com. Also find lots of math resources for teachers, parents and students at excelmath.com.