Build-at-Home Missions

Truss's Paper Bridge

Make a bridge from paper that holds a cup of coins across a gap. Shape beats thickness.

Print this sheet

Builder handle: ____________________   Date: ____________

Materials

• ☐ 10 sheets of printer paper
• ☐ Tape
• ☐ Two stacks of books the same height
• ☐ A paper or plastic cup
• ☐ Coins or small washers

Steps

1. Set the gap. Place the book stacks 20 cm (about 8 inches) apart. ☐
2. Test flat paper. Lay one flat sheet across the gap and set the cup on it. Add coins one at a time. Count before it sags. ☐
3. Fold for strength. Fold paper into tubes, accordion pleats or triangle beams. Tape them into a deck. ☐
4. Test again. Load the cup coin by coin. Write down your count. ☐
5. Improve one thing. Change one design choice and test again. Did it hold more? ☐

Finish line

Your bridge spans the 20 cm gap and holds the cup with at least 25 coins for 10 seconds.

Finish line: 25 coins, 10 seconds, no books touching the deck.

What I built: ____________________________________________

One thing I fixed: _______________________________________

Check

1. Why does a folded paper beam hold more than a flat sheet?
   • ☐ It weighs more
   • ☐ Its shape resists bending
   • ☐ Tape is magic
   • ☐ It doesn't
2. When you improve your bridge, how many design choices should you change at once?
   • ☐ Everything
   • ☐ One, so you know what made the difference
   • ☐ None
   • ☐ Three

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