## March 14 is Pi Day—and celebrating this mathematical constant makes a fun family party, any way you slice it.

### Do this

**Get on pi time: **Turn your wall clock into a pi clock by translating the hours into radians. (You can use this pi clock by SB Crafts as a model if you want to get fancy with your equations.)

**Put your pi skills to the test **with Buffon’s Needle, a geometrical probability problem that dates back to 1777. It involves dropping a needle onto a sheet of lined paper and determining the probability of the needle crossing one of the lines on the page—an answer that’s directly related to pi. The Mathematics, Science, and Technology Education (MSTE) division of the College of Education at the University of Illinois has a cool simulation that walks you through the problem.

**Take the Pi Day Challenge. **Matthew Plummer, a former math teacher at Boston’s Hanover High School, likes celebrating Pi Day so much that he created a delightful series of online pi puzzles—some of which call for mathematical solutions, some for research, and some for critical thinking.

**Write a Pilish**—a poem based on the successive digits of pi. The number of the letters in each word of your poem should equal the corresponding digit of pi: so, the first word would have three letters, the second one, the third four, and so on.

### Eat This

Bake a Beef Bourguignonne Pot Pie or Vegetable Shepherd’s Pie in a square pan so that you can make jokes about *“pi are squared,”* or just order a pizza to keep things simple. For dessert, pie is practically mandatory. (We’re having this one.)

### Read This

In Sir Cumference and the Dragon of Pi by Cindy Neuschwander, the bold knight’s son Radius must find the cure to the potion that turned his father into a fire-breathing dragon.

Pi may be an irrational number, but it’s definitely an important one — and Johnny Ball's Why Pi traces its significance through history to modern-day technology with plenty of facts and engaging anecdotes. Ball does a great job of making math — and pi — feel like important pieces of human history.

David Blatner’s lighthearted The Joy of Pi is a playful history of pi, full of intriguing anecdotes and mathematical details that never bog down into only-math-nerds-will-get-this territory.

Kids who want to try things for themselves will appreciate the hands-on pi activities in Piece of Pi: Wit-Sharpening, Brain-bruising, Number-Crunching Activities with Pi. Though some parts are a bit classroom-y, you’ll find lots of activity inspiration for middle school and up. (Younger kids with a knack for math would enjoy it, too.)

Brainy and opinionated (you will find out what Beckmann thinks of the Roman Empire — spoiler: he’s not really a fan — in addition to what he’s discovered about the history of pi), Petr Beckmann's A History of Pi isn’t for everyone. But the mathematically minded will appreciate the obsessive, nuanced detailing of this impossible number’s place in history and math.

The historical documents about pi in the fascinating collection Pi: A Source Book — including the 1897 proposed Indiana law to fix the value of pi and Lambert’s 1761 proof for the irrationality of pi — make great primary source reads for pi aficionados.

### Wear This

The Einstein Look-a-Like competition is a beloved part of Princeton University’s annual Pi Day celebration, so join the festivities by getting dressed in your Einstein-ian best.

*This post was adapted from a story in the winter 2016 issue of HSL.*