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Float Your Boat!

Students will work in teams to design, build, and test boats made of aluminum foil to explore engineering design principles, buoyancy, and problem-solving. This hands-on STEM challenge introduces basic scientific inquiry and collaborative learning. Students will design and test a tin foil boat to see how many pennies it can hold before sinking. They will record, measure, and analyze their data to find which boat design holds the most weight (mass).

Alexandria Osteen

A Third-Grade STEM Lesson

The Arizona STEM Acceleration Project

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Notes for teachers

Ensure access to water containers for testing boats.�
Prepare materials in advance in pre-counted sets.�
Have towels or mops nearby for spills.�
Encourage students to think critically and redesign if needed.�
Emphasize teamwork, creativity, and perseverance.

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List of Materials

Materials

Aluminum foil: 1 roll (cut into ~10”x10” squares, 2 per group = 10 total)�

Pennies or small weights: 300–400�

Large containers/bins of water: 5 (one per group)�

Paper towels or rags: For cleanup�

Scissors: 5 pairs (optional for reshaping foil)�

Rulers or measuring tape: 5�

Copy of the recording sheet- click here �

Pencils

Kitchen Scale

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Standards

3-5-ETS1-1: Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials.�

3-5-ETS1-2: Generate and compare multiple possible solutions to a problem.�

3-PS2-1: Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.

Arizona Math Standard:

3.MD.A.2: Measure and estimate liquid volumes and masses of objects using metric units. (Excludes compound units such as cm3 and finding the geometric volume of a container.) Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units.

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Objectives:

By the end of this lesson:

I can work with my group to design and build a boat using foil.�
I can test my boat to see how many pennies it can hold before sinking.�
I can explain why some boats float and others sink.�
I can make changes to my boat to help it float better.�
I can share what I learned with my classmates.�

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Agenda

5 min

Intro/Driving Question: "How can you build a boat out of foil that floats and holds the most pennies?"

5 min

Explain Challenge & Materials

20 min

Hands-on Activity: Build & Test Boats

5 min

Redesign & Retest (if time)

3 min

Group Sharing & Discussion

2 min

Wrap-up & Exit Ticket

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Intro/Driving Question/Opening

Driving Question: "What makes something float? How can we design a boat that holds weight without sinking?"

Instructions:

Show a real foil square and ask: “What do you think will happen if I put this in water?”�
Ask students: “How can we shape this so it holds as many pennies as possible?”�
Briefly discuss concepts of buoyancy, balance, and design.�

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Hands-on Activity Instructions

✅ Step-by-Step Instructions (with Times)

Distribute Materials (2 min)�

Give each group: 2 foil squares, 50 pennies, water container, paper towels, rulers, and recording sheet- click here�

Design Phase (3 min)�

Groups discuss and sketch their boat idea.�
Recorder notes plan in the group journal.�

Build the Boat (5 min)�

Students fold and shape one foil square into their boat design.�

Test the Boat (5–7 min)�

Carefully place boat in water and slowly add pennies one by one.�
Count how many pennies the boat can hold before sinking.�
Record the number and observations.
Weigh the pennies before and after to find the mass (e.g., “My boat held 62 g of pennies before sinking.”).�
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Redesign and Retest (5 min)�

Based on test results, use the second foil square to improve the boat’s design.�
Retest and compare results.�

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6. Group Sharing & Discussion (5 min)�

Each group answers a few guiding questions:�

What design worked best?�
What would you change if you could build again?�
What helped your boat float better this time?�

Have students compare results using difference, addition, or multiplication (e.g., “My boat held 12 more pennies than Ava’s.”).�
Teacher highlights similarities, creative ideas, and different solutions.�

7. Clean Up (2 min)�

Dry off hands, return materials, and clean up any spills.

Hands-On Activity:During the hands-on activity, guide students through the process step by step while maintaining an encouraging and organized environment. Begin by explaining the group roles — Designer, Builder, Tester, and Recorder — and emphasize that each role is important for the success of their boat. Make sure materials are pre-cut and ready at each station to save time. Demonstrate how to gently place a foil boat into the water and how to add pennies one by one while counting aloud. This helps students understand the importance of testing carefully and keeping accurate records.

As groups work, circulate around the room to ask prompting questions such as, “Why did you choose that shape?” or “What do you think caused your boat to sink?” Encourage collaboration and emphasize that it’s okay if the first design doesn’t work — the goal is to observe, learn, and improve. Keep an eye on pacing by giving time reminders like, “You have 2 more minutes to test your design.” Remind students to keep water in the containers and dry their hands after testing to prevent slips or spills.

Once groups have tested and redesigned their boats, lead a brief class discussion where each group shares their results and what they learned. Encourage students to reflect on how different shapes, sizes, and folds affected their boats' ability to float and hold weight. Use this opportunity to celebrate creative thinking and teamwork. Finally, make sure all materials are cleaned up and stations are wiped down before moving on to the wrap-up and assessment.

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Assessment

🔄 Formative (During Activity):

Observe teamwork, participation, and communication.�
Check student recording sheets for boat sketches and reflection notes.�
Ask guiding questions:�

“Why did your first design float/sink?”�
“What are you changing in your second design?”�

✅ Summative (End of Lesson or Homework):

Step 4 Reflection Questions on the recording sheet- click here�

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Differentiation

Remediation

Extension/Enrichment

Offer pre-folded boat templates as a scaffold.�

Allow more guided support and think-aloud modeling.�

Pair with peers for collaboration or use sentence starters for journal responses.

Challenge students to build a boat that floats for 1 minute while holding weight.�
Limit materials (e.g., half a sheet of foil).�
Integrate volume/mass calculations.�