Homework Help: Math 101 – understanding Pi.

“What do pies have to do with math? I looked up ‘pie’ in the math book and couldn’t find it.” This was a frazzled parent talking. It sounds like a cute math joke, but it’s true.

The word is spelled pi. It is a cute Greek letter that stands for a number a little bigger than three (approximately 3.14).

Children will need use this in math classes for many years. So, it’ll make life a lot easier for them if they understand it.

Here is a fun-to-do little activity that will help. It takes only a few minutes, and is good to do before they spend hours doing circle problems.

### Measuring the number pi, as easy as one, two, three

All you’ll need is some string (an old shoelace will do) and any round object, like a plastic serving tray or large plate.

Step 1. Measure the **circumference** of the plate using the string.

Do this by wrapping the string around the outside of the plate. Cut it to that length. That piece is one circumference long. Put it aside.

Step 2. Measure the **diameter** 0f the plate using the unused string.

Do this by placing string straight across the center of the circle. Cut it to that length. That string is one diameter long.

Step 3. Find the number **pi**.

Find the number pi by answering the question: How many lengths of the short string are needed to equal the long piece?

Just place the short piece next to the long piece of string and count how many short pieces equal the long one. (Hint: it is a little more than three). That’s all there is to it, you just found the number pi.

Pi is simply the number of diameters that equal the circumference. As you found, it is a little more than three of them. In fact, it’s closer to 3.14 of them, or using a little math-talk, the circumference is pi times the diameter (**c = pi * d**).

So, what is so special about that? What makes it special is that it works for all circles.

Encourage children to try it for themselves with different size circular objects. The answer is always the same number, pi.

P.S. Did you ever hear if *Pi Day*? Math teachers and their students celebrate it every year on March 14 — as in the date — 3_14. Now you know why.

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