March 14 is also known as "National Pi Day" because the date is 3/14. This year, the observance is particularly special, since it is the only time this century when the date will align perfectly with the first five digits in Pi (3.1415).
In 2009, Congress passed a resolution signifying March 14 as Pi Day because the irrational number is central in mathematics, science and engineering, and because learning about Pi "can be an engaging way to teach children about geometry and attract them to study science and mathematics."
The math experts among us know that Pi is the ratio of a circle's circumference to its diameter. It is an irrational and transcendental number (meaning it continues infinitely without repetition or pattern number) and has been calculated to over one trillion digits beyond its decimal point. For all circles of any size, Pi will always be the same.
What to teach your kids more about Pi? Visit PiDay.org or check out this video: