Updated March 2014
This Friday, March 14, is celebrated as Pi Day, because March 14 represented in numbers is 3.14, or Pi. Many celebrate with an afternoon Pi Day party at exactly 1:59, as those are the next three digits of Pi. (If I've just confused you, check out Visualizing Pi for a more clear explanation of the unique properties of Pi.)
And if you need another reason to celebrate math and science on Pi Day, March 14 is also Albert Einstein's birthday.
There are a lot of clever options for celebrating the day with food. And while baking a Pi pie may be the obvious choice, there are also Pi-shaped cookies, Strawberry and Nutella Pi(es) on a stick, Mac N Cheese Pi, Pizza Pi(es), and drinks with pi-shaped ice-cubes.
For math activities to share with your kids on Pi Day, check out Helping Little Hands, which has lots of great ideas using circles cut from construction paper and paper plates. And you'll find additional math pi-day fun and facts on our Pi Day Pinterest board.
And it's never too early to start planning for Pi Day 2015, which will be 3-14-15, also known as Pi to four digits.
PiDay.org has more ideas for celebrating, including this amazing video of a Pi Day Domino Spiral:
And last, if you are now inspired to celebrate unofficial math- and science-based holidays all year round, Pi day isn't the only one. There's Mole Day (celebrated on October 23 between 6:02 am and 6:02 pm) and Square Root Day (last celebrated on 3-3-9, and next celebrated on 4-4-16).
And let's not stop here! Do you have an unofficial math or science holiday to add to the list? Leave a comment below!