⛵ Which boat shape carries the most pennies?

My hypothesis

If I change the shape of the boat, then how many pennies it carries before it sinks will ______, because ______.

🔊 You fill in the blanks. Think about how much water each boat pushes out of the way before water spills over its sides. A guess is a good because: the test finds out.

Change, measure, keep the same

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

• 🥈 Foil: 3 squares, 20 cm across
• 🪙 Pennies: about 100
• 🛁 A tub of water
• 📏 A ruler

Steps

1. Tear three squares of foil, all 20 cm across.🔊
2. Fold one into a flat raft with its edges turned up a little.🔊
3. Fold one into a square box and one into a round bowl.🔊
4. Float the raft and add pennies one at a time.🔊
5. Count the pennies when water comes in, and write it down.🔊
6. Dry the foil, shape it again and test it two more times.🔊
7. Do three tests with the box and three with the bowl.🔊
8. Draw a bar for each boat. Which carried the most?🔊

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

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.

Why it works

🔊 A boat floats when it pushes enough water out of the way to hold up its weight. Boats with higher sides can sink deeper before water spills in, so they push more water aside and hold more pennies. Spreading the pennies out helps too, because no corner dips under first.

Going further (7th and up): Change a second thing: make each shape with low sides and with high sides, and test all six.

Board layout

This project at your grade

From 4th grade up, the table gets a mean column. See every project for 1st 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 boat and measured how many pennies it carries before it sinks, in pennies.
• What did you keep the same, and why does that matter? I kept the same size of foil and adding pennies one at a time the same, so the only difference was the shape of the boat.
• 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 make each shape with low sides and with high sides, and test all six.

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

• 🥚 How much salt does it take to float an egg?3rd–7th grade · 1 day of testing · free🧪 Water, ice and mixing · 🧂 Kitchen things
• 🌉 Which paper bridge shape holds the most coins?2nd–7th grade · 1 day of testing · free🚗 How things move · ✂️ Paper, tape and toys

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