Quick and easy Pi Lesson

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Home : 2008 : February : 21

Quick and easy Pi Lesson
By Paul S.

This lesson is quick and easy. One might say it is "easy as pie". LOL I kill myself. =)

Okay, well, the lesson is simple. Take the kids outside to a tetherball circle. (You can ask the kids how to make a circle
and draw one using chalk and a piece of string.) Ask the kids how to measure the circle's circumference. Get a bunch of answers. Have 3 or so kids merely walk around the circle and then down the center. Use people with different sized feet. You write down the meaurements on a piece of paper to the nearest 1/2 step or 3/4 step, etc.

Go inside and write the numbers on the

board... circumference first and then diameter. They might be 22 and 7. Ask students what they notice. The conversation might go something like.

S: "The circumference is bigger."
T: "How much bigger?"
S: "3 times bigger"
T: "Exactly 3 times bigger?"
S: "No, more than 3 times bigger."
T: "How can we find exactly how many times bigger it isw?"
S: "Divide."
Teacher will then divide each under a column "C/d" as a fraction. All the numbers will be close to 3.14. Some bigger and some smaller.

T: "How can we deal with the fact that some were measured too big and some too small?"
S: "Take the average."

Take the average and you will find an answer close to 3.14 or exactly 3.14. Then discuss that a special number named pi, which is the ration between circumference and diameter. Tell them that we have measured circles really carefully and found what they did - that the number is really close to 3.14.

Ask them how to rewrite the equation with C by itself. One or more of my 5th graders will say "C=pi times d".

There you go. Whole thing takes 20-30 min.

Paul