What you’ll need

  • several sheets of A4 paper
  • scissors
  • adhesive tape, glue
  • two equally high stacks of books
  • small toy figures
  • glass of water

How to do it

1. Use the books to make a trench over which the bridge will pass. When you place a sheet of A4 paper across the two stacks, it may link the two but it can’t withstand any additional weight.

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2. Strengthen your bridge. Folding is your first option: a sheet folded to make a rectangular box, which you fix with some tape, is a bit stronger than an unfolded sheet.

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3. But your bridge will be sturdier if you fold a second sheet of paper in a zigzag and insert it into the rectangular paper box.

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4. Rolling is another option: strengthen your bridge using rolls of paper taped together.

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5. Can you think of any other ways to strengthen the bridge? How many sheets of paper would you need for a bridge that can bear a full glass of water?

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Well spotted!

Paper is not an especially good load-bearing material. But depending on how you arrange and combine different layers of paper, you can make some amazingly strong constructions!

What’s the secret?

The aim when building a bridge is to achieve the highest possible load-bearing capacity with the bridge itself weighing as little as possible. There are different ways you can do this:

  1. Reinforce the bridge: rolled tubes of paper are stiff. The more tightly they are rolled, the stronger the bridge.
  2. Distribute the weight of the bridge evenly: a bundle of several thin rolls of paper stuck together with adhesive tape is stronger than a single thick roll of paper. The bundle takes up the weight of the load and distributes it evenly across the bridge surface. Honeycomb structures are also very sturdy. Here, the weight is distributed across multiple vertical walls inside the construction.
  3. Support the bridge: place "pillars" of folded paper beneath the bridge.