Grade 3 · Low-Tech Builds · Lesson 27

Wind-Powered Sail Car

Catch moving air and turn it into straight, controlled travel.

Time2–3 × 60 minutesTeamsTeams of 3–4EquipmentNo powered equipment required

Project inspiration · 3 images

See, build, and test

Use these images to understand the kind of making, details, and testing involved. They are inspiration—not designs students must copy.

Finished student example for Wind-Powered Sail Car
01Finished project
Close construction and materials view for Wind-Powered Sail Car
02Construction detail
Students testing and recording results for Wind-Powered Sail Car
03Student testing

Student directions · Grade 3

What will you make and do?

You will build a small wheeled car that moves when a fan pushes its sail. It must start from wind power, not from your hand giving it a push.

Teacher overview: Students will plan the specific object described below, make and test a first version, then use their results to improve it. Read one step together, demonstrate the unfamiliar action, and let students complete that step before moving on.

  1. 1Plan your project

    Sketch the car from the side and above. Mark the two axles and draw two sail shapes to compare.

  2. 2Make the first parts

    Make a light cardboard body with straight axle guides. Fit wheels and check that they turn freely before adding a sail.

  3. 3Put it together

    Attach a removable mast and paper sail. Keep it upright without making the car top-heavy.

  4. 4Test it fairly

    Place the car on the same start line with the same fan distance and setting. Record distance and sideways movement across repeated trials.

  5. 5Improve one part

    Change either sail shape or wheel alignment, not both. Repeat the same wind test to find out which change helped.

  6. 6Show and turn in

    Show the wind-powered car, two sail ideas and a results table with the fan conditions labeled.

How will you know it works?

  • Car moves from wind power alone
  • Travels mostly straight
  • Sail design shows an original visual identity

Before you move on

Tell a partner what you are making. Point to the part you will work on next. Draw or dictate your test notes if writing slows you down.

Machine cutting, printer setup and electrical power-on require adult approval. A basic-materials model is a valid way to demonstrate the design when equipment is unavailable.

Keep your plan, test notes and before-and-after evidence with the printable design brief below. Use the detailed teacher plan and any coding guide for tool instructions. These steps continue across the lesson’s meetings, not all in one sitting.

For teachers

Engineering standards

This shows how the lesson connects to the national NGSS engineering standards and what student work you can collect.

Assessed

3-5-ETS1-1

Teams define the user or purpose, success criteria, and limits before building.

What students show: Problem statement with measurable criteria and material constraints.
Practiced

3-5-ETS1-2

Students sketch and compare at least two solutions before choosing or combining features.

What students show: Two labeled ideas and an evidence-based design choice.
Assessed

3-5-ETS1-3

Teams use a repeatable low-tech test—release each car from the same line with the fan at the same speed and distance—then revise one feature.

What students show: Test notes, before-and-after design, and explanation of improvement.

Materials

  • Cardboard bases and paper sails
  • Straws, skewers with covered ends, and bottle-cap wheels
  • Tape, clay, paper clips, and fabric scraps
  • Rulers, pencils, markers, and planning paper
  • Masking tape, glue dots, paper fasteners, clips, and rubber bands
  • Scissors and other teacher-approved hand tools
  • Reused and student-proposed materials approved before use

Teacher preparation

  1. Set out a broad materials buffet instead of identical kits.
  2. Build one small test rig, not a finished example students may copy.
  3. Mark size, time, and material limits visibly.
  4. Prepare a team planning page and shared test-data table.
  5. Create a safe holding area for drying or unfinished builds.

Step by step

How to teach it

Day 1 · 0–20

Explore the challenge

  1. Introduce the mission: Build a small car that travels straight using only air from a classroom fan.
  2. Identify the user or audience and what success should look like.
  3. Explore how sample materials bend, fold, join, compress, slide, or balance.
Day 1 · 20–60

Imagine and prototype

  1. Each student sketches a different possibility.
  2. Teams compare ideas against criteria and constraints.
  3. Build a quick model using only part of the material budget.
Day 2 · 0–35

Build and test

  1. Complete the first working version.
  2. Use the same procedure each time: release each car from the same line with the fan at the same speed and distance.
  3. Record what worked, what failed, and where it happened.
Day 2 · 35–60

Improve with evidence

  1. Change one important feature rather than rebuilding randomly.
  2. Repeat the same test and compare results.
  3. Add color, surface, form, or story details that strengthen the purpose.
Optional Day 3

Gallery and challenge round

  1. Display designs with a one-sentence mission and test result.
  2. Let visitors try the project using the same rules.
  3. Teams explain one tradeoff and one idea they would try next.

Assessment

  • Problem statement includes a purpose, criteria, and constraints.
  • Sketches show meaningfully different ideas.
  • Material choices are explained using properties.
  • Test is repeatable and produces recorded evidence.
  • Revision responds to a specific result or failure point.

Supports & extensions

  • Offer picture directions and sample joining techniques.
  • Provide pre-cut pieces, adaptive scissors, or larger materials.
  • Allow students to explain through drawing, speaking, or demonstration.
  • Assign flexible roles: designer, builder, tester, recorder, and artist.
  • Extension: reduce material use while maintaining performance.

Safety & responsible use

  • Use only clean, teacher-approved reused materials.
  • Carry scissors and tools safely; cut away from hands and bodies.
  • Cover sharp cardboard corners, wire ends, skewers, or fasteners.
  • Use a defined test zone and keep faces away from moving or falling parts.
  • Teacher handles hot glue, craft knives, and any tool not approved for students.

No-machine alternative

The entire project is already designed for common classroom materials. Substitute paper folds, tabs, slots, string, tape, or found objects while keeping the same criteria and fair-test cycle.

Printable student design brief

The challenge

Build a small car that travels straight using only air from a classroom fan.

Success criteria

  • Car moves from wind power alone
  • Travels mostly straight
  • Sail design shows an original visual identity

Constraints

  • Fan operated by teacher
  • Uses the assigned footprint
  • Hands leave the car before the test

Engineer’s notes

Our design should…
We chose this material because…
Our first test showed…
The failure point was…
We changed… because…
Next time we would…
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