Grade 3 · Coding & Electronics · Lesson 60

Push-Button Lighthouse

Build one complete LED circuit and open or close it with a simple switch.

Time2 × 45 minutesTeamsPairs; switch maker and tester rolesEquipmentTwo-AA circuit kit; no computer or Arduino

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.

Generated project illustrations are shared by the two grade versions of this project. Follow your grade’s directions and starter recipe—not the pictured screen or hidden wiring.

Project overview: Illustrative push-button cardboard lighthouse project
01Project overview
Making detail: Illustrative push-button cardboard lighthouse project
02Making detail
Testing the project: Illustrative push-button cardboard lighthouse project
03Testing the project

Student directions · Grade 3

What will you make and do?

You will make a cardboard lighthouse with a red LED that lights when a visitor presses a broad flap switch and goes off when they release it. No coding is needed.

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 lighthouse base and choose a reachable switch position. Mark the light, two separated foil pads and covered two-AA battery holder.

  2. 2Make the first parts

    Build a broad base and short cardboard tower. Tape one foil pad to the base and the other beneath a hinged flap; use a paper spacer to hold them apart.

  3. 3Put it together

    With power disconnected, follow the exact starter connection list with adult help. Keep the 330 Ω resistor in series with the red LED and obtain an adult check before power-on.

  4. 4Test it fairly

    For three gentle presses, record off before pressing, on while pressed and off after release. Keep the press position the same.

  5. 5Improve one part

    Switch off and disconnect power before adjusting the spacer or a loose contact. Never bypass the resistor; ask the adult to check polarity if it stays dark.

  6. 6Show and turn in

    Show the lighthouse working and submit the labeled circuit drawing and three-trial sheet. Point to the gap that makes the switch work.

How will you know it works?

  • Light is off with the switch open and on when the pads meet.
  • The switch releases without staying closed in three trials.
  • The student points to the complete path and identifies the switch gap.

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.

Beginner sequence · Step 3 of 3

Start here

Readiness check: Can students distinguish connected from separated foil pads and identify a battery holder? Teacher demonstrates LED polarity and checks all connections.

Exact starter recipe

POWER OFF before connecting. Use insulated clips with exposed metal kept apart.
Battery holder + (red lead) → 330 Ω resistor → red LED anode (+, long leg)
LED cathode (−, short leg / flat rim) → foil pad A
Foil pad B → battery holder − (black lead)
Leave an air gap between the pads; pressing the cardboard flap brings A and B together.
Teacher checks the loop, resistor, LED polarity, and absence of a short before power-on.
Release = gap = light off. Press = contact = light on.
Illustrative photographs are NOT a wiring diagram; follow this connection list.

Make the simplest version work first. Then use the test and extension in this lesson.

Teacher learning resources

Preview external resources before class. The circuit reference explains the science; use this page’s specified AA kit and connection list for the build.

For teachers

Engineering standards

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

Practiced

3-5-ETS1-1

Define the user's need for push-button lighthouse and agree on the listed success criteria and limits.

What students show: A stated user need and checked criteria; this is engineering-design practice, not a separate coding standard.
Practiced

3-5-ETS1-2

Compare two possible routes, pet behaviors, or switch arrangements before selecting one for the user.

What students show: Two small plans and a reason for the selected design.
Assessed

3-5-ETS1-3

Repeat the stated test under the same conditions, identify a failure, change one feature, and retest.

What students show: Before-and-after test entries and an explanation connecting the change to the result.

Materials

  • Covered switched holder with two AA alkaline cells, teacher-issued
  • One standard red LED and one 330 Ω resistor per pair; adult confirms ratings
  • Four or five insulated clip leads; teacher prepares connections
  • Cardboard tube and broad cardboard base, paper tape, two foil pads
  • Thin folded cardboard flap and small paper spacer; no spring metal or hot glue
  • Printable design brief

Teacher preparation

  1. Check readiness: Can students distinguish connected from separated foil pads and identify a battery holder? Teacher demonstrates LED polarity and checks all connections.
  2. Adult tests each red LED and resistor with the exact two-AA holder. Keep all holders switched off and disconnected during assembly.
  3. Prepare the cardboard tube, cover sharp LED leads, and make a broad hinged switch flap with two separate foil pads.
  4. Demonstrate the series loop using the connection list; explain that the resistor stays in the circuit for every test.
  5. Prepare the printable design brief at the end of this page. Use the project picture as inspiration, not a technical diagram or a required artistic finish.

Step by step

How to teach it

Class 1 · 0–5

Meet the beginner challenge

  1. Build a cardboard lighthouse whose red light turns on when a visitor presses a broad cardboard switch and turns off when it is released.
  2. Read the criteria together. Ask students to predict what the system should do.
Class 1 · 5–12

Model one working action

  1. Make a broad cardboard base and stand a short cardboard lighthouse tube on it. Leave room for the switch and battery holder.
  2. With power disconnected, tape one foil pad to the base and another beneath a hinged cardboard flap so they face each other.
  3. Use the exact starter recipe below. Ask a student to explain the action before demonstrating a second step.
Class 1 · 12–20

Compare two small plans

  1. Sketch or arrange two possible solutions using the same materials.
  2. Compare each plan against the criteria; choose one and state a reason.
Class 1 · 20–38

Build the smallest working version

  1. Use a folded paper spacer to hold the pads apart until pressed. Keep the foil from touching any other conductor.
  2. Follow the connection list with adult help. Place the red LED at the top without letting its leads touch each other.
  3. Ask the teacher to inspect and turn on the holder. Press the flap gently, then release.
Class 1 · 38–45

Check and save

  1. Show one working action. Record where you stopped and what you need next.
  2. Switch off and disconnect the battery holder; an adult stores components.
  3. Return materials and reset the workspace.
Class 2 · 0–8

Rebuild understanding

  1. Read the saved plan and predict the first test.
  2. Adult rechecks the circuit before power-on.
Class 2 · 8–22

Test fairly

  1. Keep the same battery holder, LED, resistor, and press position.
  2. For three trials, record light off before press, on during press, and off after release.
  3. If it does not light, switch off first. Adult checks polarity, clips, resistor, and whether the foil pads meet. Never bypass the resistor.
Class 2 · 22–35

Improve one thing

  1. Identify the first point where the result differed from the prediction.
  2. Change one instruction, code block, or mechanical feature. Repeat exactly the same test.
  3. If the core skill is secure, offer the extension; otherwise use the support option.
Class 2 · 35–45

Share evidence and clean

  1. Let another pair try the project with your directions.
  2. Use the worksheet to show an original result, a change, and the new result.
  3. Switch off, disconnect, and return the battery holder to the adult.

Assessment

  • Light is off with the switch open and on when the pads meet.
  • The switch releases without staying closed in three trials.
  • The student points to the complete path and identifies the switch gap.
  • Student predicts an outcome before testing.
  • Test record distinguishes expected and actual results.
  • Student explains why the revision helps; neat decoration and speed are not assessment criteria.

Supports & extensions

  • Give students an adult-checked circuit with an open switch gap. Their task is to build and explain the broad cardboard switch.
  • Offer larger cards or tools, a stabilized work surface, picture cues, partner assistance, and spoken or dictated evidence.
  • Extension after success: Compare two flap widths for ease of pressing while keeping the circuit and spacer unchanged.

Safety & responsible use

  • Use only two AA alkaline cells in a covered, switched holder (nominal 3 V), one red LED, and a 330 Ω series resistor. Teacher checks component ratings and the complete circuit before switching on.
  • Never join battery terminals directly. Disconnect the holder before changing connections. Stop immediately and tell an adult if anything warms, leaks, or smells unusual.
  • No coin/button batteries, mains wiring, soldering, loose wire stripping, or lithium cells. Adults prepare leads and cover sharp ends; collect all components afterward.
  • Keep liquids away; do not wear the circuit or put parts in the mouth. This is a tabletop model, not a real navigation or safety light.

No-machine alternative

Use a paper lighthouse and red/gray window cards. Show red only when a paper switch is closed; label it a circuit model, not a powered circuit.

Printable student design brief

The challenge

Build a cardboard lighthouse whose red light turns on when a visitor presses a broad cardboard switch and turns off when it is released.

Success criteria

  • Light is off with the switch open and on when the pads meet.
  • The switch releases without staying closed in three trials.
  • The student points to the complete path and identifies the switch gap.

Constraints

  • Only the teacher-approved 3 V kit; adult approval before power-on.
  • Use two 45-minute meetings; start with the working system before decoration.
  • Keep test conditions consistent and change only one feature at a time.

Engineer’s notes

Our visitor needs a light that…
Sketch two places for the switch; circle the easier place to press.
Draw the loop using the connection list. Mark the resistor and switch gap.
Trial 1 / 2 / 3: before press… during press… after release…
One part we adjusted with power off…
Retest result… Why did the gap matter?…

Printable beginner test record

Predict. Try. Improve.

Name ____________________ Partner ____________________

Our success rule: __________________________________________________

TrialInput / actionExpected resultFirst resultResult after one change
1
2
3
4
5
6
7
8
9
10

Use three rows for the introductory tests or all ten for switch reliability. Write the held, released, or other-key state for each sensing test.

One thing we changed: ______________________________________________

Things we kept the same: ____________________________________________

Our evidence shows: _________________________________________________

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