Age range: 6–12
Time: 20–40 minutes
Concepts: forces, compression/tension, engineering design
Goal
Discover how folding and shaping paper changes its load-bearing strength.
Materials
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10–15 sheets of plain printer paper
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2 equal-height stacks of books (supports)
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Coins or small washers (weights)
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Ruler and pencil
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Tape (optional)
Safety
No special risks. Supervise younger kids around stacks of books so they don’t topple.
Steps
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Build supports: Place two stacks of books ~20 cm apart to act as bridge abutments.
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Baseline test: Lay one flat sheet of paper across. Add coins one at a time until it sags/fails. Record the maximum.
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Try a fold: Fold a sheet into an accordion (1–2 cm pleats). Bridge the gap and repeat the load test.
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Add beams: Roll a sheet into a tight tube and tape the seam. Place two or three tubes under a flat sheet as “girders.” Test again.
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Compare shapes: Test U-channels (paper folded into a “U”) and I-beams (two U’s taped back-to-back).
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Data table: Record design vs. max coin load.
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Optimize: Combine features (accordion deck + tube girders) and attempt a final best design.
What’s Happening
Folds and curved shapes increase the moment of inertia, resisting bending. Tubes distribute load and place more material farther from the neutral axis—stronger for the same mass.
Troubleshooting
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If bridges slide off supports, roughen with a strip of tape.
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If coins roll, use washers or stack coins in small cups.
Extensions
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Keep total paper mass constant; compare strength-to-weight.
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Increase the span and see which design scales best.
