Paper Bridge
Word of the day: bridge
“Can one sheet of paper hold up a whole pile of coins?”
Grab
- two stacks of books the same height
- sheets of paper
- coins, blocks or toy cars as weights
Do
- Lay a flat sheet across the gap between the books. Put one coin in the middle. It sags.
- Fold another sheet back and forth like a fan (accordion). Lay it across.
- Add coins one at a time and count. How many before it falls?
- Try rolling a sheet into a tube, or folding the edges up into a U.
The big moment
A floppy sheet, folded, holds a pile of coins.
Ask (guess first, then try)
- What made the flat paper strong?
- Which bridge held the most?
What's going on (for you)
Shape matters more than material. Folding makes the paper deep from top to bottom, and depth is what resists bending. Real beams use the same trick: an I-beam or corrugated cardboard is folded or shaped to be deep without much material.
If they want more
Tear open a cardboard box edge and look at the wavy layer inside.