What is pi?

Can you imagine a number that never ends? That number, known as “pi,” is found by dividing the circumference of a circle by its diameter, and it is used all around you every day. Engineers and architects use pi to design structures, scientists use it to calculate the orbits of planets and stars, and it’s even used to determine how well a baseball pitcher throws a ball. Because pi is rounded to 3.14, March 14 is National Pi Day! Here are some fun activities to celebrate one of the coolest numbers in math!

How do you find pi?

With a circle!

For materials, you’ll need a round plate, a pencil, and a roll of measuring tape. 

Directions:

1. Wrap the measuring tape around the edge of the plate, see how many inches it is, and write that measurement down. 
2. Stretch the measuring tape across the middle of the plate, measuring from one edge to the other, and write that measurement down too. 
3. Divide the first measurement (the circumference) by the second measurement (the diameter). You should get 3.14 or a number very close to it. 

No matter how big or small the circle (the dinner plate, in this case), pi is always the same!

How do you get pie?

Make some! (Or have your kids make it.) This easy no-bake chocolate peanut butter pie is a tasty way to celebrate math.

Freezer Chocolate Peanut Butter Pie

Makes two whole pies.

Ingredients:

2 chocolate graham cracker pie crusts

1 8 oz. package cream cheese, softened

½ tsp. vanilla extract

1 ⅓ cup powdered sugar

1 ¼ cup peanut butter

1 cup milk

1 16 oz. tub of whipped topping, thawed

Directions:

1. Use a mixer to beat together the softened cream cheese, vanilla extract, and powdered sugar.
2. Add in the peanut butter and milk, and then beat until the mixture is smooth.
3. Gently stir in the whipped topping until just combined.
4. Pour into the pie crusts and refrigerate at least 6 hours (or overnight).

How do you play with pi?

Make a pi paper chain.

Pi Paper Chain

You’ll need paper, scissors, a stapler, and a pencil or marker.

Directions:

1. Cut construction paper, card stock, or even regular paper into strips. (You can either cut freehand, use a ruler to draw lines as a guide, or fold your paper like a little accordion and then cut down each fold.)
2. Fold the first strip into a circle and staple the ends together.
3. Slide one end of another strip through the circle you just made.
4. Make a circle with the second strip, stapling the ends together. Repeat until you’ve used all your strips.
5. Write a number of pi on each link in your paper chain. Here are some more digits to get you started: 3.14159265358979323846264338. (You can find a million digits at piday.org/million, but nobody has time for that!)

For all of its incredible uses, both practical and fun, pi certainly deserves its very own holiday! What is your favorite Pi Day activity?