Easy As Pi: Introducing the Magic Number to Kids

The Significance of Pi

Pi is a mathematical constant. It's the number you arrive at when you divide the circumference of a circle by its diameter. Stated another way, every circle has a circumference that is roughly 3.14 times its diameter. While pi is typically rounded to 3.14, it's an irrational number that, theoretically, can be calculated to an infinite number of decimal places. While computers continue to expand the possibilities for calculating pi, the current record stands at five trillion decimal places.

Pi's most popular use involves Euclidean geometry and understanding circles. Since pi is a constant, it enables us to determine the circumference of any circle when we know the diameter, or vice versa. This also means that knowing the circumference of a circle allows us to determine its area, since the area is based on the circle's diameter.

Throughout geometry, pi has practical uses. It's essential for calculating the area and volume of shapes that are based on circles; these include spheres, cones and ellipses. Pi is also useful in physics, where it appears in a number of significant principles and equations. These include Einstein's field equation of general relativity and Heisenberg's uncertainty principle.

Fun with Pi

There are myriad ways for you and your kids to have fun with pi. For example, you can challenge your kids to see who can memorize the most digits. While most people only know pi as 3.14, trying to memorize it further is an endlessly tricky activity. The current world record is held by Chao Lu of China, who correctly recited 67,890 digits of pi in 2005. There are numerous ways to memorize pi, including creating a song or using piems, which are poems wherein the number of letters in each word represents a digit.

If you're looking for a fun, hands-on project with pi, try making a pi chain out of construction paper loops. Each of the ten digits can be represented by a different color. The chain can be as long as your kids can make it. Schools that have undertaken this project have made chains of more than 10,000 links.

Pi Day

Pi Day is March 14th (3/14). Physicist Larry Shaw, who worked at the San Francisco Exploratorium, created the holiday in 1988. In 2009, the U.S. House of Representatives passed a resolution recognizing the day as National Pi Day.

One fun way to celebrate pi day is to bake a pie with your kids. Since its inception, Pi Day has been celebrated with the baking and eating of pies. Pies and pi have more in common than just being homophones. First, pies are circles. Also, when 3.14 is held up to a mirror, it spells 'PIE.'

Pi Day is also a day to celebrate Albert Einstein since March 14th is Einstein's birthday. At Princeton University, Pi Day brings an extended celebration of math and the sciences. There are activities for everyone from small children to adults. They range from academic competitions to pie throwing contests.