Grade 3 · Laser & Vinyl · Lesson 07

Classroom Noise Traffic Light

Turn sound-level data into a calm visual reminder for shared learning spaces.

Time3 × 60 minutes + adult fabricationTeamsTeams of 3–4EquipmentScratch or simple sound circuit + optional laser cutter

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 Classroom Noise Traffic Light
01Finished project
Close construction and materials view for Classroom Noise Traffic Light
02Construction detail
Students testing and recording results for Classroom Noise Traffic Light
03Student testing

Student quick guide

What are we doing?

1

Meet the real-world challenge: Give a class a visual reminder when group-work sound moves above an agreed level.

2

Choose materials, build the control system, and connect the sound meter, sensor, or student observer to the green-yellow-red display.

3

Test the same way each time, study the evidence, and improve one part.

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 who needs the classroom noise traffic light and set measurable performance, safety, material, and time limits.

What students show: User-centered problem statement with criteria and constraints.
Practiced

3-5-ETS1-2

Teams compare at least two circuit, code, or enclosure ideas against the success criteria.

What students show: Labeled system diagrams and a recorded design choice.
Assessed

3-5-ETS1-3

Teams run a repeatable test—play the same three teacher-approved sound samples at a fixed distance—then change one variable and retest.

What students show: Test table, code or build revision, and evidence-based explanation.

Materials

  • Cardboard, paper, craft sticks, tape, reusable building pieces, and student-proposed materials
  • Project platform: Scratch or simple sound circuit + optional laser cutter
  • Breadboard, paper-circuit supplies, or low-voltage power when needed
  • sound meter, sensor, or student observer input component or student-designed substitute
  • green-yellow-red display output component or student-designed substitute
  • LEDs, resistors, jumper wires, copper tape, switches, and clips as needed
  • Laser Cutting materials for an optional case, sign, mount, or model
  • Computer with approved coding or simulation tools when needed
  • Planning sheet, ruler, and test-data table

Teacher preparation

  1. Build and test one possible reference solution without making it the required design.
  2. Prepare a basic-materials table plus optional electronics and fabrication stations.
  3. If coding is used, prepare a starter option for ordered thresholds in Scratch, cards, or an optional controller; students may propose another workable control method.
  4. Prepare optional fabrication templates and a file rule beginning G3_07.
  5. Mark adult approval points before power-on and machine fabrication.

Step by step

How to teach it

Day 1 · 0–20

Meet the user and define success

  1. Introduce the application: Give a class a visual reminder when group-work sound moves above an agreed level.
  2. Identify the user, need, criteria, and constraints.
  3. Draw a system map with input → code → output.
Day 1 · 20–60

Build a first solution

  1. Choose basic, electronic, and fabricated materials based on the team's idea.
  2. Build with power disconnected whenever electronics are used.
  3. Complete an adult check, then troubleshoot one connection or physical feature at a time.
Day 2 · 0–30

Create the behavior

  1. Create the first working control using ordered thresholds in Scratch, cards, or an optional controller.
  2. Predict what one rule, connection, or code change will do before testing it.
  3. Make the system understandable with labels, diagrams, comments, or coding blocks.
Day 2 · 30–60

Test and improve

  1. Use the same procedure each time: play the same three teacher-approved sound samples at a fixed distance.
  2. Record at least three results.
  3. Change one code, circuit, or physical-design variable and retest.
Day 3

Fabricate and present

  1. Design a laser cutting part that protects, mounts, or explains the electronics.
  2. Adult reviews and operates fabrication equipment where required.
  3. Connect the finished system and demonstrate how the evidence improved it.

Assessment

  • Problem statement names a real user and measurable need.
  • Circuit matches the team diagram and uses components safely.
  • Program connects the intended input to the intended output.
  • Test conditions remain consistent and include recorded evidence.
  • Revision addresses a documented failure or user need.

Supports & extensions

  • Use color-coded wires and a photograph of each breadboard step.
  • Provide block coding or partially completed code with one change at a time.
  • Assign roles: circuit builder, coder, tester, and recorder.
  • Let students explain findings orally or with labeled diagrams.
  • Extension: add a second sensor, output, data display, or operating mode.

Safety & responsible use

  • Use only teacher-approved low-voltage classroom electronics; never connect projects to wall current.
  • Disconnect power before changing wires or components.
  • Use the correct resistor with every standard LED and stop immediately if a part becomes hot.
  • An adult handles soldering, laser cutting, printer setup, blades, and final power approval.
  • Keep liquids away from boards unless a sealed, teacher-approved sensor activity specifically requires them.

No-machine alternative

Build with cardboard, paper mechanisms, paper circuits, or a free on-screen simulator. Students may invent another safe way to model the same function, then compare ideas, test one variable, collect evidence, and revise.

Printable student design brief

The challenge

Create a working classroom noise traffic light for this need: Give a class a visual reminder when group-work sound moves above an agreed level.

Success criteria

  • Changes color at useful sound levels
  • Responds consistently to repeated samples
  • Communicates without recording anyone's speech

Constraints

  • Measures level only and stores no voices
  • Display may be cardboard, digital, or laser-cut
  • Uses the same listening position during testing

Engineer’s notes

Our user needs…
The input tells the system…
Our code decides…
The output responds by…
Our test data showed…
We improved… because…
← Return to September lessons