**Geometry:**

**3.14159265358979323846264338327950288
. . . etc.**

**Today's
Snack:** Pi
is an endless number. Make yourself an endless supply of popcorn in a tall
bowl. You'll keep reaching and reaching, and it never seems to . . . uh oh, a
bowl of tasty popcorn might come to an end after all! Enjoy ice water with a
twist of lemon in it along with your popcorn treat.

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**Supplies:**

**Flexible measuring tape, such as
seamstresses use**

**Scratch paper and pencil | several
circular items**

"Pi" (pronounced like apple "pie") is a
Greek alphabet letter. In symbol form, it looks like this:

**π**

You remember that the **circumference** of a circle is the **distance around** the circle, and the **diameter** is the **distance across** the center of a circle.

What do those have to do with pi? Plenty.

The ancient Greeks figured out that if
you divide the circumference of any circular object by its diameter, it'll
always turn out to be a number around 3.1416.

The numbers after the decimal point
actually go on into infinity, with no particular pattern repeat, so it's a
fascinating situation. Knowing about pi is really important for understanding
the relationships between objects in everything from manufacturing design to
space exploration.

For example, did you know that the Earth's
circumference is about 24,902 miles, and its diameter is about 7,927 miles? If
you round the diameter up to 8,000 miles, you can see that the circumference is
a little bit more than three times as long as the diameter. Use a calculator,
and you'll see just how close it comes to pi - it's "off" by a couple of
thousandths only because we haven't given you the exact mileage, to the decimal
points. But you can see the relationship.

Want to see for yourself? OK, take a
flexible measuring tape, a piece of scratch paper and a pencil, and let's make
a chart. We've suggested some circular objects to get you started, but bet you
can think of many more to measure. Note that many measuring tapes show inches
as well as millimeters and centimeters, so take your pick. Just be sure to use
the same unit of measurement (inches, feet, millimeters or centimeters) for
both measurements - the object's circumference as well as its diameter:

**Round Object Circumference Diameter **__Circumference__

** Diameter**

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Quarter

Jar lid

Pop can

Dinner plate

Wastebasket

Basketball

Car tire

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ideas:**

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