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3.14 Day

March 14th, 2013 by

Yes it is circumference over diameter day, March 14. The value of Pi is generally well known(at least to two decimal places) to students, but where it is derived from and its universality is not. If you are going to do just one thing related to Pi today in your classroom, do this one quick activity: Have students identify various circular objects around the room, or use a series of circular drawings you provide. They should all be differently sized. Tell them to find the circumference and diameter for each circle. The first challenge is that you are not going to let them calculate the circumference using the value of pi, so they will have to measure the circumference itself. You can provide string for example to help students with this.  The second piece is the determine the diameter of the circles, which will go quickly. You can assign some students to use Imperial measurements, some metric.

Next have them chart out the values of the circumference and diameter of each circle. The circles should have a wide variation in size. At the end, when they have taken all their measurements and recorded them, the aha! moment should occur. The final column in the chart should be the ratio of the two values, calculated to several decimal places. All will be close to 3.14, the value of pi. It won’t matter what units they used, or the size of the circle. Pi is pi. There will be some discrepancies due to measurement errors and calculator rounding, and those subjects are worthy of discussion because anticipating these sorts of errors will help in any further experiments and data collection long term.


For other resources on Pi Day, visit:


Pi Day At The Exploratorium


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