Which Bridge Is Strongest? A Paper Test
Take one flat piece of paper and lay it between two cups. Put a penny on it — it sags and falls! Now fold that same paper like a fan, with lots of little hills and valleys. Set it back on the cups and add pennies. It can hold ten, twenty, sometimes more! The paper did not get thicker. Its SHAPE got stronger. Today you are a bridge tester, and shape is your secret.
What You'll Learn
Today you will: 1. Learn that a bridge holds weight up high so we can cross over. 2. See how folding paper makes it much stronger. 3. Test which paper bridge holds the most pennies. 4. Count and cheer for your strongest shape!
What Is a Bridge?
A bridge is a path that goes OVER something — like water, a road, or a muddy ditch. It lets you cross without falling in. A bridge has to be strong. When you walk on it, you push DOWN. The bridge must push back UP and not sag or break. Cars, trucks, and lots of people can be on a real bridge at once, so it has to be very, very strong.
When you fold paper into a fan shape, you make little walls. Those walls hold the weight up. A flat paper has no walls, so it flops. More folds usually means more strong!
Shapes That Are Strong
Builders love the triangle. A triangle does not squish when you push on it, so bridges are full of triangles. An arch is strong too. An arch is a curve like a rainbow. When weight pushes down on an arch, the curve carries it down to the ground on both sides. Old stone bridges use arches, and some have stood for hundreds of years!
Match each thing to what it does.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
You put a penny on a flat paper bridge and it sags down. What should you do to make it stronger?
Which shape do bridge builders use because it does NOT squish?
The Penny Bridge Contest
1. Get two paper cups and set them a hand-width apart. 2. Lay one flat paper across them and gently add pennies one at a time. Count how many it holds before it falls. 3. Take a NEW paper, fold it like a fan, and lay it across. 4. Add pennies again and count. 5. Draw the two bridges and write the two numbers under them. Deliverable: your drawing showing which bridge held more pennies, with a circle around the winner.
Flashcards — click each card to reveal the answer
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