Grade 5 · Art & Design · Lesson 18

Replacement-Part Detectives

Reverse-engineer a safe, noncritical classroom part instead of throwing an object away.

Time3 × 60 minutes + adult fabricationTeamsTeams of 3–4EquipmentMeasurement tools + Bambu P1S fleet

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 Replacement-Part Detectives
01Finished project
Close construction and materials view for Replacement-Part Detectives
02Construction detail
Students testing and recording results for Replacement-Part Detectives
03Student testing

Student directions · Grade 5

What will you make and do?

You will design a replacement for one missing or broken noncritical part on a teacher-approved object. The new part must fit and do its original job without damaging the object.

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

    Inspect the safe object and identify what the missing part did. Measure every surface the replacement must touch; sketch two possible forms.

  2. 2Make the first parts

    Make a cardboard, foam or clay fit model. Try it without force and mark where it is too tight, too loose or in the way.

  3. 3Put it together

    Model a small fit sample in CAD before requesting the full printed part. Record which dimensions you changed and let the teacher check the file.

  4. 4Test it fairly

    Use the same object and action for repeated trials, such as fitting, turning or spacing. Record whether the part stays in place and can be removed.

  5. 5Improve one part

    Adjust one measured feature from the test evidence and retest. Stop if a part requires force or the object begins to deform.

  6. 6Show and turn in

    Show the original problem and replacement. Submit measurements, fit revisions and limits: no repair of electrical, load-bearing or safety-critical equipment.

How will you know it works?

  • Fits without forcing or damaging the object
  • Performs the intended noncritical function
  • Uses less material than replacing the whole object

Before you move on

Explain which measurement, input or design choice you are testing. Predict the result and record what stays the same so your comparison is fair.

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 who needs the replacement-part detectives 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—run the same fit, movement, and repeated-use test on every version—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: Measurement tools + Bambu P1S fleet
  • Breadboard, paper-circuit supplies, or low-voltage power when needed
  • caliper measurements, fit requirements, and user feedback input component or student-designed substitute
  • a documented 3D-printed replacement part output component or student-designed substitute
  • LEDs, resistors, jumper wires, copper tape, switches, and clips as needed
  • 3D Printing 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 parametric CAD, tolerances, and version control; students may propose another workable control method.
  4. Prepare optional fabrication templates and a file rule beginning G5_18.
  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: Extend the useful life of a classroom object by replacing a safe, noncritical plastic part.
  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 parametric CAD, tolerances, and version control.
  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: run the same fit, movement, and repeated-use test on every version.
  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 3d printing 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 replacement-part detectives for this need: Extend the useful life of a classroom object by replacing a safe, noncritical plastic part.

Success criteria

  • Fits without forcing or damaging the object
  • Performs the intended noncritical function
  • Uses less material than replacing the whole object

Constraints

  • No electrical, load-bearing, food-contact, heat, or safety-critical parts
  • Teacher approves the object before work begins
  • Final file includes measurements, version number, and limitations

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…
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