Grade 3 · Design & Engineering · Lesson 136

Sail Car

Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.

Time2 × 45 minutesTeamsPairs; alternate builder and testerEquipmentBasic classroom design materials; no powered equipment

Your project in view

What you are making

Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.

This generated example illustrates one possible finished design—not actual student work. Use the lesson’s sizes, connected parts and safety steps; your colors and creative details can be different.

Generated finished-project example for Sail Car: Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.
Sail Car · Generated project example

Student directions · Grade 3

What will you make and do?

Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.

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

    Draw two car shapes. Mark wheel, axle and sail positions; choose a design with room for wheels to turn.

  2. 2Make the first parts

    Build the cardboard body. Slide teacher-prepared axles through straw bearings and attach the four wheels.

  3. 3Put it together

    Attach a paper-cup sail securely above the body. Spin every wheel and fix rubbing before testing.

  4. 4Test it fairly

    Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials.

  5. 5Improve one part

    Change only the sail angle or size. Repeat with the same fan, strokes and starting point.

  6. 6Show and turn in

    Turn in the car, plan and distance table. Explain why the wheel and sail positions matter.

How will you know it works?

  • Rolls forward under fan-powered air
  • All four wheels remain attached through three trials
  • Record the stated test and explain one revision

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

Define the need in Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan. Agree on the two success checks and the listed material limits.

What students show: Two labeled ideas with the target and limits stated.
Practiced

3-5-ETS1-2

Compare the ideas using the project checks: Rolls forward under fan-powered air; All four wheels remain attached through three trials.

What students show: A selected design with a reason connected to a success check.
Assessed

3-5-ETS1-3

Test, change one feature and retest: Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials. Change only the sail angle or size. Repeat with the same fan, strokes and starting point.

What students show: Before-and-after results collected under the same conditions.

Materials

  • Cardboard
  • four bottle caps or card wheels
  • two paper straws
  • two wooden skewers prepared by teacher
  • paper cup
  • tape
  • hand fan
  • Pencil, planning paper and the printable design brief below

Teacher preparation

  1. Gather per-pair materials: Cardboard; four bottle caps or card wheels; two paper straws; two wooden skewers prepared by teacher; paper cup; tape; hand fan.
  2. Make one rough sample and rehearse the exact test: Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials.
  3. Set the size, load or distance marks mentioned in the steps before class. Demonstrate an ordinary first attempt, not a perfect model to copy.
  4. Prepare any holes, fasteners or difficult cuts for students. Check the stated safety note and clear the testing space.

Step by step

How to teach it

Meeting 1 · 0–8 min

See the job and plan

  1. Introduce the finished object: Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.
  2. Draw two car shapes. Mark wheel, axle and sail positions; choose a design with room for wheels to turn.
  3. Students say what would count as a successful result.
Meeting 1 · 8–18 min

Model the unfamiliar action

  1. Demonstrate slowly: Build the cardboard body. Slide teacher-prepared axles through straw bearings and attach the four wheels.
  2. Pause so partners can repeat the action; provide prepared parts if cutting or folding blocks progress.
Meeting 1 · 18–35 min

Build the first version

  1. Attach a paper-cup sail securely above the body. Spin every wheel and fix rubbing before testing.
  2. Partners swap builder and checker roles halfway through. Check the working part before decorating.
Meeting 1 · 35–45 min

Try once and save

  1. Run one trial of the stated test to locate an obvious problem. Do not count a changed procedure as a fair comparison.
  2. Label and store the model; sketch its current shape and clear the work area.
Meeting 2 · 0–8 min

Predict and set up

  1. Revisit the two success checks. Agree on identical starting conditions and prepare a before/after results table.
Meeting 2 · 8–23 min

Collect evidence

  1. Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials.
  2. One student operates while the other records. Swap for a later trial while noting a change of operator if it affects the result.
Meeting 2 · 23–35 min

Change one thing

  1. Change only the sail angle or size. Repeat with the same fan, strokes and starting point.
  2. Keep the original results rather than replacing them with only the best attempt.
Meeting 2 · 35–45 min

Explain and clean up

  1. Turn in the car, plan and distance table. Explain why the wheel and sail positions matter.
  2. Collect the brief and results; separate reusable materials and clean the test area.

Assessment

  • Rolls forward under fan-powered air
  • All four wheels remain attached through three trials
  • Student demonstrates the actual task: Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials.
  • Record includes failures as well as successes.
  • Student identifies one changed feature and uses the retest to explain the result.

Supports & extensions

  • Provide fold marks or pre-cut parts; accept drawings or dictated observations.
  • Start with the smallest working version of sail car before decoration.
  • Extension after success: choose one more value for the same tested feature, predict its effect and repeat place the car at the same start.

Safety & responsible use

  • Teacher checks materials and test conditions before use. Use classroom scissors; adults prepare difficult cuts, holes and fasteners.
  • No powered tools, coding, hot glue or electrical circuits are required. Keep moving objects contained and test loads light.
  • Teacher prepares axle holes and trims points. Use only a hand fan in a clear floor lane; never blow or launch toward faces.

No-machine alternative

Use prepared paper parts, larger pieces or an adult-assisted version of the same build. Keep the functional task: Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan. If physical testing is not possible, label sketches as predictions rather than measured results.

Printable student design brief

The challenge

Build a lightweight car with a paper-cup sail that rolls when pushed by air from a hand fan.

Success criteria

  • Rolls forward under fan-powered air
  • All four wheels remain attached through three trials
  • Record the stated test and explain one revision

Constraints

  • Use only the listed teacher-approved materials
  • Stay within the teacher-set size, load and test-space limits
  • Two 45-minute meetings; keep the first version simple

Engineer’s notes

Who uses this object, and what should it do?
Draw two possible designs. Label the working parts and circle your choice.
Which size, fold, gap or position must you measure or mark?
Before testing, predict what will happen: Place the car at the same start. Give five equal fan strokes from the marked spot and measure distance in three trials.
Record each trial: condition / expected result / actual result.
Draw the ONE change you made. What stayed the same?
Record the retest. Did the change help, not help, or leave the result uncertain?
Show and explain: one result that supports your conclusion.
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