Week Eighteen: Pi Day!

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October 10, 2015 by libraryheather

Program Title: Pi Day!

Target Age Range: Grades 4-6

Program Length: 60 minutes

Brief Description:
A celebration of 3.14 on 3/14!

-12 frozen hot dogs

-Open container large enough to hold all 12 hot dogs

-Colored masking tape

-12 rolls masking tape (4 different colors, 3 of each color)

-Cloth measuring tapes (1 per group/table)

-Blank paper

-Pencils or pens (1 per participant)


-Calculators (1 per group/table)

-Cookies (budget at least 1 per participant)


-A variety of round objects to practice calculating pi (lids, mugs, cans, etc)

-Large sheet of white butcher paper

-Optional: Pie! ūüôā …and forks.

Cost: $0-50

Advanced Preparation:
-Print out fraction-to-decimal conversion sheets (2 per table).

-Write multiple digits of pi on a whiteboard (or similar).

-Draw 1 large black circle on each of the 3 big sheets of butcher paper, and then two smaller concentric circles within the large circle. The smallest circle should be slightly larger than a roll of masking tape.

-Carefully measure out and lay down masking tape lines per the instructions for the Buffon’s Hot Dogs experiment.

-Optional: Create a paper crown with the pi symbol on it to crown a “King/Queen of Pi.”

Program Outline:
1. Settling in, welcome, introductions, sing A Pi Day Carol together: 5 minutes

2. Explain what pi is and how we calculate it: 5 minutes

3. Practice calculating pi by measuring cookies and other round objects. Eat cookies (and maybe even pie!) while you are doing this: 15 minutes

4. Buffon’s Hot Dogs: 20 minutes

5. Pi Shuffleboard: 15 minutes  (see Special Instructions and Procedures below)

Fraction-to-Decimal Conversion Sheets

Special Instructions and Procedures:
Explaining Pi:
Explain that Pi is the ratio of a circle’s circumference to its diameter. Be sure that everyone is clear on the definition of ‘circumference’ and ‘diameter.’ Demonstrate how to calculate Pi (dividing the circumference of a circle by its diameter). If you’d like, you can tell them about how Pi is an ‘irrational number’ / the history of Pi.

Calculating Pi:
Each group got a variety of circular objects to measure (including cookies, which they were allowed to eat). We told them to work in pairs–one person holding the measuring tape/string around and across the circular object, the other person reading and recording the measurements. Then they calculated Pi for each object.

Before letting them start, we explained that some measuring tape/rulers have 8 hash marks between the inches, and some have 16. We said: “When you’re measuring, you will need to count those hash marks. For instance, if I pulled this measuring tape around something circular and it fell on 4″ and one-two-three-four-five of these 8 hash marks, it would be 4 5/8.” ¬†Because we can’t divide that easily, we have fraction-to-decimal conversion sheets on the desks, so that you can change 4 5/8″ to 4.0625.”

Buffon’s Hot Dogs:
This hilarious idea came from WikiHow. Mostly, we just wanted kids to get away with tossing frozen hot dogs in the library. However, if you’re hesitant about using food, you can use something else long and hard, like unsharpened pencils or craft sticks (another good website about this experiment can be found at DecodedScience.org).

We had 1 person tossing hot dogs at a time. Their only instructions were to toss (not throw) the hot dogs randomly toward the lines on the floor. We elaborated that ‘randomly,’ means just that–random, and not trying to aim for a particular line or trying to get it far outside the lines, etc. If the hot dog lands completely outside of the marked lines, that toss should be redone (so, you can see why it is undesirable for participants to try to make that happen!). A staff member recorded the number of tosses and crosses on a sheet by making tick marks. To get to 300 tosses, 25 kids threw 12 hot dogs each. If you have more or fewer kids than that, make adjustments to the number of tosses accordingly. At the end, the staff members did the math up on a white board and further explained the results.

Pi Shuffleboard:
This game comes from Susan Meyer (found on PiDay.org). Because our meeting room is carpeted, we used a big sheet of white butcher paper and drew 1 large circle on it with two smaller circles inside of the big circle. These are the rules we gave to the participants: 4 people will play each round, and each person gets 3 rolls of colored masking tape. Your goal is to get 1 of your 3 rolls the closest to the exact middle of the circle–even if that means knocking someone else’s roll out of place. Before you begin each round, all 4 people in the group decide whether everyone will toss or roll the rolls of tape. The person who gets closest to the middle is declared the winner, and gets to play the next round against three new people. This will go on until everyone has played at least once.

If you want to speed this up, you could make two boards with three players for each round on each board. This, however, would require 18 rolls of colored masking tape (6 different colors).

Resources Used:
Calculate Pi by Throwing Frozen Hot Dogs

Pi Day Activities for Teachers

The Math Forum @ Drexel: Pi Day Songs

DecodedScience.org: The Buffon Needle Drop

Additional Resources:
Layers of Learning: Pi Day Activities

TeachPi.org: Activities

Scholastic: Exploring Pi

Exploratorium: Pi Day

Exploratorium: History of Pi

The Reading Buddies: Edible Pi Day Centers

Avoision.com: Pi10K

What we would do differently:
Ultimately, we were unable to obtain 6 sets of cloth measuring tapes. So, we also used pre-cut pieces of yarn to wrap around our cookies/cups/lids, and then measured that length on a ruler. Unfortunately, yarn is quite stretchy, so the calculations ended up being iffy. In the future, investing in cloth measuring tape would be best.

There is a great idea from Sheryl Rosenberger on PiDay.org to make color-coded bracelets/necklaces for the digits of pi. We would love to do this project the next time we celebrate Pi Day. We would likely do this in lieu of Buffon’s Hot Dogs.

We were surprised to find that we had many young Pi enthusiasts who attended. As such, we had an impromptu contest: how many digits of pi can you recite/write down? We then gave a “King of Pi” paper crown to the winner.

Adaptation for older/younger audience:
We wouldn’t immediately recommend this for an audience younger than 4th-6th graders, unless it was a family event in which parents could help with any math/measuring difficulties. This would likely be fun for middle schoolers, too–even with no major modifications. There are so many great ideas for Pi Day out there, we’re confident that you can something entertaining for pretty much any audience.

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