Aluminum Foil Boat

Design and build a boat from aluminum foil that can hold as many pennies as possible before sinking or capsizing.

DESIGN CHALLENGE MATERIALS

Supplies and Equipment:

  • Shallow plastic bin

  • Water

  • Towels

  • Pennies (several hundred) or other weights

  • Optional: pictures of different kinds of boats

Consumables:

  • Aluminum foil

Getting Ready

Cut the foil into uniform squares. The foil squares can be anywhere from 4" x 4" to 12" x 12". Keep in mind that larger squares will make larger boats, which may require more pennies to sink. Fill your plastic bin with a few inches of water. Have towels ready to dry your hands or clean up spills.

INTRODUCTION

  • Think about different boats you have seen. What is the same about them? How are they different? (Similar shapes or materials, different means of propulsion, etc.)

  • What makes a boat float? (Boats weigh less than the water they push aside.)

  • What’s a common way to ship things across the ocean? (Cargo ship or freighter.) Some cargo ships travel with a load of containers that is larger than the ship—why do you think it doesn’t sink? (Their flat, hollow design keeps them buoyant.)

INSTRUCTIONS

Ask participants more focused questions about buoyancy. What happens to a full glass of water when you add a bunch of ice cubes to it? What happens to a ship when more and more weight is added to it?

Introduce the design challenge.

Give each person or team a square of aluminum foil.

Give participants as much time as they need to build their boats. They may test them to make sure they float before adding weight. Start adding weight to the boat. Make sure to distribute the weight evenly.

  • Place pennies one by one into the boat. Participants can keep track or count along.

  • Keep adding weight until the boat sinks.

  • Make observations along the way. Does the boat change shape, spring a leak, or lean in one direction?

Ask questions to encourage further discovery. Redesign the boat and test again.


ACTIVITY VARIATIONS

Calculate the weight of displaced water just before sinking. Add the weight of the dry foil boat plus the weight of the pennies. A standard US cent weighs 2.5g. Was this more or less than you thought the boat could hold?

Use other materials for building the boat, like clay or paper.

After testing a boat in water, try another fluid. Will the boat hold the same amount of weight floating on salt water? What about vegetable oil?