Magic Jig-Saw Puzzle by pengtt

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```									Magic Jig-Saw Puzzle
Magicians can make things appear, like when they pull a rabbit out of an empty hat,
or disappear. Try this bit of magic with your class to make a mysterious hole appear
and disappear. Then find out about the kind of math that makes this seemingly
impossible puzzle possible.

You will need:
•   Puzzle (print and cutout the puzzle shown on the last page)
•   Scissors
•   1 piece of construction paper
•   Glue

Try this:
1. Cut around the entire puzzle shown on the last page. Glue it to a piece of
construction paper.

2. Trim the edges of the construction paper so it's the same size as the entire puzzle.
Now, cut out the individual shapes within the puzzle. Throw away the black puzzle
piece from the middle.

3. Lay the puzzle pieces on a table. Make sure the letters are facing up. Put the puzzle
back together so there is a rectangle with a hole in the middle. Ask students: Can
you rearrange the pieces so that the hole disappears? (No.) What if you turned the
pieces upside down?

4. Tell students they can find out. First they need to say the magic words — Hocus-
Pocus! — and turn the pieces over so the construction paper side faces up. (The
letters shouldn't be visible.)

5. Arrange the puzzle pieces in a rectangle. Ask students: Can you find a way to
arrange the shapes so that the hole disappears? (Yes.)

6. As a class, discuss the puzzle. How were they able to get rid of the hole on one
side and not the other? Was it magic that allowed them to do this or something
else? Have them investigate the puzzle pieces. Does anything change when they
turn the pieces over?

Look on the next page to find out how this trick works!
Magic Jig-Saw Puzzle
What's happening?
Magicians usually don't tell you how they do the amazing effects you see during a
magic show, but we'll share the secret of this trick.

The magic puzzle is a visual illusion — something that fools the eye and brain into
seeing something that's not there — or at least something that is not what it appears
to be! Your eyes tell you one thing (the hole disappeared!) and your brain tries to
make sense of it (hmm… That's impossible!) When your brain can't quite understand
how something works, that's a kind of magic! To a scientist, it's an area ripe for more
investigation.

If you look closely at the two puzzles, you should notice a very slight difference. The
second puzzle you make is slightly smaller than the first puzzle with the hole. Most
people never notice the difference.

You don't need magic to explain the trick of the Magic Jig-Saw Puzzle. It can be
explained with a certain kind of math called topology. In geography, a topologist
makes maps. But in math, a topologist understands the mysteries of shapes, folds
and surfaces. Professional magicians use an understanding of math — from simple
addition to topology — to surprise and astound their audience. You can use math as
a tool to make magic, too!

For students to perform this trick for other friends and family, they should practice
until they can put the puzzle back together quickly. But remember — a magician is
not supposed to reveal the secrets of his or her trick!
Magic Jig-Saw Puzzle

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