Science Fair

Grown-ups

Which paper bridge shape holds the most coins?

2nd–7th grade · 1 day of testing · free · ages 7 to 13 · 50 minutes a sitting

  • 👶 Small parts
Index-Card Bridge: the Workshop build the paper bridge shapes project grows from

My hypothesis

If I change the shape of the paper, then how many pennies it holds before it falls will ______, because ______.

You fill in the blanks. Think about which way the paper is standing when the pennies press down on it. A guess is a good because: the test finds out.

Change, measure, keep the same

CHANGE

the shape of the paper: Flat, Folded like a fan, Rolled into tubes

MEASURE

how many pennies it holds before it falls, in pennies

KEEP THE SAME

  • the same size and kind of paper
  • the same gap between the books
  • adding pennies one at a time in the middle

Scientists call the thing you change the independent variable and the thing you measure the dependent variable. The things you keep the same are the controls: if one of them changed too, you wouldn't know which change made the difference. Try each of the 3 levels 3 times.

What you need

  • Paper: about 15 sheets, all the same
  • Some books: 2 stacks the same height
  • Paper cups: 1 small one
  • Pennies: about 100
  • 🩹 Tape
  • 📏 A ruler

Steps

  1. Make two stacks of books the same height, 20 cm apart.
  2. Lay a flat sheet of paper across the gap and stand the cup in the middle.
  3. Add pennies one at a time until the bridge falls in, and write down the count.
  4. Do it twice more with a new flat sheet each time.
  5. Fold a new sheet back and forth like a fan, and test it three times.
  6. Roll sheets into tubes, tape them side by side, and test them three times.
  7. Draw a bar for each shape and find the strongest.

Every step is one you can do yourself, with a grown-up nearby. Write each number down straight away, in the table below, so nothing is lost.

Your results table

MY RESULTSPeabody 🦉 peabody.kids/science-fair

Name ______________________ Fair day ____________

Question: Which paper bridge shape holds the most coins?

I changed: Bridge shape   I measured: how many pennies it holds before it falls (pennies)

Bridge shapeTry 1 (pennies)Try 2 (pennies)Try 3 (pennies)Mean
Flat
Folded like a fan
Rolled into tubes

MY GRAPH (a bar graph: bridge shape along the bottom, pennies up the side)

What I noticed: ______________________________________________

From 4th grade, add the tries for each level and divide by how many there were: that's the mean, and it goes in the last column. Then draw a bar graph, one bar for each thing you tried.

📊 Make my graph🖨 Print the whole packet (9 pages)🛠 Run it as an engineering project

Why it works

Flat paper bends easily, so it sags under a little weight. Folds and tubes stand some of the paper up on its edge, and paper on its edge is much harder to bend. That's why real bridges use beams, folds and tubes instead of flat sheets.

Going further (7th and up): Change a second thing: test the fan shape with one, two and three sheets stacked, and graph how the strength grows.

Board layout

MY BOARD · 36 × 48 in tri-foldPeabody 🦉 peabody.kids/science-fair
  1. ❓ Question (10 × 8 in): Which paper bridge shape holds the most coins?
  2. 💭 Hypothesis (10 × 9 in): If I change the shape of the paper, then how many pennies it holds before it falls will ______, because ______.
  3. 🧺 Materials (10 × 12 in): 4 things: see your list.
  4. 🪜 Steps (22 × 9 in): 7 steps, three tries at each level.
  5. 📊 Results (22 × 16 in): Your table (Bridge shape down the side, tries across) and your bar graph.
  6. ✅ Conclusion (10 × 14 in): My hypothesis was right / partly right / not right. I know because…

Materials to list: Paper; Some books; Paper cups; Pennies.

Bring photos or drawings of your test. Nothing wet, hot, powered or alive on the table.

This project at your grade

1st–3rd gradeTries: three at each level (one is fine at a first fair). The table: levels and tries, numbers or pictures. The graph: a picture, or a simple bar graph. The conclusion: what happened, in their words.
4th–6th gradeTries: three at each level. The table: units in the header and a mean column. The graph: a bar graph, or a line for a number that grows. The conclusion: right, partly or not, and the numbers that show it.
7th grade and upTries: three or more at each level. The table: a mean for every level of both tests. The graph: a graph with two lines or two sets of bars. The conclusion: the numbers, what might have gone wrong, and a next question. Second variable: test the fan shape with one, two and three sheets stacked, and graph how the strength grows.

From 4th grade up, the table gets a mean column. See every project for 2nd grade, or print a blank results table.

What a judge will ask

  • What did you change, and what did you measure? I changed the shape of the paper and measured how many pennies it holds before it falls, in pennies.
  • What did you keep the same, and why does that matter? I kept the same size and kind of paper and the same gap between the books the same, so the only difference was the shape of the paper.
  • How many times did you test it? 3 times at each of my 3 levels.
  • If you did it again, what would you change or test next? I'd test the fan shape with one, two and three sheets stacked, and graph how the strength grows.

Make it yours

Keep this project on this device and Peabody counts down to your fair day, with a plan for each day. Nothing is sent anywhere.

Try next

🔨 From the Workshop: this project grows from a Workshop build, with picture steps of its own.

👨‍👩‍👧 For grown-ups and teachers: how much to help, the safety rules, and running a school fair. Science fair v0.16.1 · Checked .

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