# Coin Through Index Card Magic

Amaze your friends when you slip a quarter through a dime-sized hole!

What if we told you that you can fit a quarter through a dime-sized hole in an index card? Would you believe it was possible? It is possible, and we can even show you how you can try it for yourself!

## Experiment Materials

• Index card
• Dime
• Quarter
• Pen or pencil
• Scissors

## Experiment

### 1

Fold the index card in half along the short side (hamburger style), and crease it along the middle.

### 2

Unfold the index card. Lay the dime in the center of the index card, along the seam and trace around it.

### 3

Fold the index card in half and use the scissors to carefully cut out the outline of the dime.

### 4

Unfold the card so that it is flat again.  Now, leaving the card flat, try to fit a quarter through the hole without tearing the card.  It doesn’t work!

### 5

Fold the card in half again, and drop the quarter between the folds so it is in the center of the card.

### 6

Holding the card with both hands, carefully bend the card by bringing both top corners closer to each other. Keep playing with the position of the card until the quarter finds it way through the hole!

### 7

Check the card for tears to prove that you were able to fit the quarter through the hole without tearing the card.

## How Does It Work

A quarter is a larger coin and has a larger diameter than a dime.  That’s why the quarter is unable to fit through the dime-sized circle when the card is flat.

When the card is folded in half and is bent just slightly, the circle in the center changes and becomes elliptical.  That means that the opening becomes wider, allowing the quarter to slip through.

## Take It Further

Try the same trick with fitting a half dollar through a penny-sized hole.  This is sure to impress your friends!

## Science Fair Connection

Fitting a quarter through a dime-sized hole is pretty cool, but it isn’t a science fair project.  You can create a science fair project by identifying a variable, or something that changes, in this experiment.  Let’s take a look at some of the variable options that might work:

• Try fitting other items that are larger than a dime through the hole.  Will objects with other shapes fit through the hole? What is the largest object you can fit through the hole?
• Try changing the shape of the hole. What larger items or shapes will fit through the hole now?
• Try changing the size of the hole.  What is largest object you can fit through the different sizes of holes? Does the size of the largest object change in proportion with the size of the hole?

That’s just a couple of ideas, but you aren’t limited to those! Try coming up with different ideas of variables and give them a try.  Remember, you can only change one thing at a time.  If you are testing different shapes, make sure that the other factors are remaining the same.