Tell your class you’re celebrating Pi Day and they’ll be dreaming of apple pies, cream pies, or maybe even pizza pies. Don’t let that enthusiasm fade when you tell them you’re actually celebrating math! Get your class pumped up for math this year with these simple Pi Day activities. (Note: Baked pie and pizza pie are always encouraged and appreciated!)

## What is Pi Day?

For any non-mathletes who need a quick refresher. . . Pi is a number that represents the ratio of a circle’s circumference (the distance around a circle) to its diameter (the width of a circle). No matter how large or small the circle—from Earth to a golf ball—the ratio will always be approximately 3.14. This makes Pi a constant number. Pi is also an irrational number, meaning its decimal representation never ends and never repeats. It has been calculated to its one-millionth digit.

Since 1988, March 14 (3/14 or 3.14) has been recognized as Pi Day and in 2009, it was made a national holiday in the U.S. In more recent years Pi Day has gained popularity in classrooms everywhere!

## Celebrating Pi Day

### Pi Day Banner

What you’ll need:

- paper plates
- string/yarn
- markers/crayons
- other art supplies

On each paper plate, draw a large block number representing a digit of Pi. Have one paper plate for each student in your class. (For 24 students, create a plate for 3 + 23 following digits). Let your students color and decorate the number on their pie plate however they’d like. Then string them up in order and hang across your classroom.

### Pi Collage

What you’ll need:

- paper
- magazines
- scissors
- glue sticks

With the digits of Pi written out in the front of the classroom for guidance, students should find the numbers in the magazines, cut them out, and glue them onto their paper. Then decorate your class with the digits of Pi!

For inspiration, use the image above which was created by the Exploratorium (where Pi Day was said to have originated). It also a fantastic resource for Pi Day history and activities.

### Cutting Pi

What you’ll need:

- circular objects of different sizes (mugs, jars, plates, cans, oatmeal containers)
- string
- scissors

Break your class into small groups and give each group a circular object. Using their string, they should measure the circumference of the circle and cut the string to that length. Then, using that same piece of string, have them measure the diameter of their circle and cut the string to that length. Repeat this until they eventually have 3 pieces of string that are the length of the diameter, plus a small remaining piece of string that you can measure. Bingo! That’s the Pi theorem in action!

Repeat this process with other circular objects of different sizes. Students will learn that no matter how big or small the circle, the circumference divided by the diameter will always result in 3.14…approximately, of course.

### Pi Day Reading

**Enemy Pie –** Even younger students can join in the Pi Day fun! Do you know the secret recipe for getting rid of an enemy? This book reinforces the idea of turning enemies into friends.

**Sir Cumference and the Dragon of Pi –** This adventure features Sir Cumference, Lady Di of Ameter, and Radius. (Get it???) It’s an engaging way to introduce Pi and other mathematical concepts to your class.

**PIE –** The name says it all! Not only will the mystery of a missing pie crust recipe keep your students guessing, each chapter also includes a bake-from-scratch pie recipe. This book is part of the One School, One Book program,

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