This week we will see that you can do science experiments anytime, even while
cleaning out the refrigerator. Well, to be honest, it distracted me from
cleaning out the refrigerator, but eventually the job will get done. I
promise. I really do promise. To avoid cleaning your refrig.... I mean to
try this experiment, you will need:

- a long glass jar, like olives come in
- water
- a magnifying glass

Look in your refrigerator, and get that old jar of olives from the bottom
shelf. Put the last few olives onto a plate. Add a few pickles, some cubes
of cheese, some celery, and a few grapes, and you will have a nice snack to eat
while you do this experiment.

Wash the olive jar and remove the label. You may have to let it soak in hot
water to get the label off, which will give you time to enjoy your snack.

Fill a large bowl or dish pan with water. Place the jar under the water and
turn it so all the air comes out. Still under water, put the lid on the
jar. When you remove it from the water, there should not be any air bubbles
inside. Dry the outside of the jar.

Print the following words on a sheet of paper. Print them neatly, just as
they are here. If your handwriting is like mine, type the words, and print
them with your printer.

HIDE MY BIKE

Yes, it is a strange thing to write, but soon you will understand. Place
the olive jar over the words, with the side of the jar touching the paper.
Reading through the jar, what do you see? You see the same words, maybe a bit
bigger depending on your jar, but otherwise just the same.

Now comes the interesting part. Lift the olive jar a couple of inches off
the paper, and read the words through the jar again. What happened? The
words HIDE and BIKE look the same, but the word MY is upside down! Why?

To understand, we need to know a bit about lenses. Hold a magnifying glass
a few inches above the words. Looking through the lens, the words look
larger, and they are all right side up. Then try holding the magnifying glass
about 2 feet in front of you and looking at your room through it. Everything
is upside down and backwards. Quite a difference.

As light passes through the lens of the magnifying glass, it is bent. The
light bends toward the center, so light from the top is bent downwards. Light
from the bottom is bent upwards. Light from the right is bent to the left.
Light from the left is bent to the right. As the light moves away from the
lens, you reach a point where all the light comes together. You have seen
that point if you have ever used a magnifying glass to burn a piece of paper.
As the light passes that point, it spreads out again, but now if is reversed.
Beyond the focal point, the light from the top is now at the bottom. The
light from the right is now on the left. The image looks upside down and
backwards.

Now, lets compare that with our olive jar. Holding the olive jar
horizontally over the words, you will now see that you have a lens that is a
cylinder instead of circle. It is curved on the top and bottom, but it does not curve
inwards from the sides. The light from the top is bent downwards, and the
light from the bottom is bent upwards, but the light on the left and right is
not bent towards the center. As a result, when you move past the focal point,
the image is flipped upside down, but not reversed left to right. The words
HIDE and BIKE are made up of letters that look the same upside down as they do
right side up. That lets them look the same when you read them through the
olive jar. The letters M, Y, and most of the other letters in the alphabet
look different when they are upside down,

If you want a challenge, make a list of the letters that look normal though
the olive jar. Can you write an entire sentence that looks right through your
long lens? If you come up with a good one, email it to me. I'll post the
best ones. Now I have to finish my snack, and get back to cleaning out the
refrigerator.