Paper Bridge

Introduction

Bridges come in all shapes, sizes, and materials. let us find what makes a bridge the strongest in this fun filled activity as kid build simple bridges with paper and test to see how much weight they can hold. 

Materials

•    Two thick books or small boxes

•     Papers

•     Tape

•     Coins or other small, heavy objects to use as weights (small rocks, nuts and bolts, etc.)

Instructions

1.     Place your books about 10 inches apart.

2.     Lay a single piece of paper across the books.

3.     Place a penny in the middle of the paper. What happens? If the "bridge" does not collapse, try adding more pennies.

4.     Fold the piece of paper in half lengthwise, and try again. Does the bridge hold more pennies this time?

5.     Now fold the paper into a "U channel" shape. Fold the paper in half lengthwise twice. Then, fold up the edges to form walls. Use tape to hold the edges in place, to prevent the bridge from unfolding.

6.     Place a penny in the middle of the bridge. One at a time, keep adding pennies along the length of the bridge. This simulates how real cars and people are spread out along the length of a bridge. Do not stack them all on top of each other in the middle.

Note - If you fill up the whole bridge, start a second layer of pennies. Keep adding pennies until the bridge collapses. 

Experiment with different shapes for your bridge. For example, try changing the number of times you fold the paper in half, the width of the base, or the height of the walls.

Think about:

What shape makes the strongest bridge? 

What Happened?

You probably found that a single, flat piece of paper could barely support its own weight, let alone any pennies. Folding the paper in half may have made it little strong enough to support a few pennies. The more times you folded the paper in half, the stronger it got. Changing the shape of the bridge to like letters "C," "U," or "I" will make bridge vertical "walls" significantly stronger, and it could probably hold dozens of pennies. While a horizontal piece of paper is very easy to bend in the vertical direction, the vertical wall sections are very difficult to bend in the vertical direction, making the bridge very strong (which support more pennies and thus more weight). 

For Further Exploration

1.     Try building bridges from other household materials, like aluminum foil, wax paper, thick paper or cardstock. Which material is the strongest?

2.     Experiment with different shapes. What happens if you roll a piece of paper into a cylindrical tube, or fold it into a "W" shape?

3.     Try making a longer bridge by taping two pieces of paper together end-to-end. How long can you make your bridge before it collapses under its own weight?

4. Experiment with support. What happens if you add a piece of paper rolled into a cylindrical tube, and support center of the bride from bottom?