Fold a paper bridge
Can a single sheet hold a load over a ten-centimetre gap? Test a flat span, change the folds and compare how much each version holds.
25 min · Engineering · Suggested starting age band 7–11.
Gather paper, two books, counters.
Set up a fair test
Work on the floor or a low table. Gather two equal-height books, three sheets of the same paper and a handful of identical counters or similar small blocks. Keep small pieces away from younger siblings. Stand the books ten centimetres apart and mark their positions.
Build and load
- Lay a sheet flat between the books. Predict where it will bend.
- Place one counter at a time in the middle. Record how many it carries before the middle touches the table.
- Fold a second sheet into a concertina. Lay the creases in the direction across the gap, leaving both ends resting on the books. Load it in the same place.
- Choose a third shape together. Try folded-up sides or a rolled section. Keep the paper, gap, counters and their position the same.
What changed?
Compare the side views of the bridges. Where did the flat sheet sag? Where did a crease start to collapse? Folded paper has depth that a flat sheet lacks. A heavier load need not mean a better design if the bridge keeps rolling sideways. Keep a sketch of the version you would build again and write down the next single change you would test.