In this lesson, school-aged children explore a creative variation of the classic “Making of a Chip” activity. Instead of looking at a whole wafer, learners zoom inside a single chip where each LED represents one transistor, focusing on the tiny web of wiring that links them together. Because billions of transistors are useless without proper connections, students work in design teams to build a working, multi-layer microchip model using Play-Doh (the conductor) and clay (the insulator) so that powering specific terminals lights the correct LEDs. By the end of the session, learners experience the full mini-cycle of semiconductor engineering—circuit mapping, insulator layering, interconnect wiring, and functional light testing.
Learners will:
- Explain the difference between a conductor and an insulator
- Describe transistors and interconnects and how they are stacked in layers.
- Model the real carve-and-fill patterning process using a mask, one layer at a time.
- Build and troubleshoot a circuit so that specific terminals control specific transistors without short circuits.
Lesson Plan Presentation
Materials & Preparation
Material amounts are suggested per team of two school-aged children.
- Play-Doh — the conductor (5–6 small cans)
Clay — the insulator (2–3 pieces)- Index Cards or cardstock paper — for masks (one per layer)
- Green and Red LEDs (5 mm)
- 6 V battery holder with wires (4 AA)
- 4 AA batteries
- Index-card base (~3″ diameter) and two sandwich-bag (4–5″)
- Tools: scissors, hole punch, tweezers (optional)
- Worksheet and engineering notebook
- Wafer to chip video
Engineering Design Challenge
Design and build a model of a microchip that focuses on the interconnections linking its transistors. When the correct terminals are connected to a battery, the correct LEDs should light. Three challenges build up to the final model.
Criteria & Constraints
- Watch the demonstrations before building.
- Build with Play-Doh as the conductor and clay / plasticine as the insulator.
- Create a separate carton-paper mask for every layer of the chip.
- Powering BLUE + RED must light the red LED(s); powering BLUE + GREEN must light the green LED(s).
- Use only the materials provided.
Activity Instructions & Procedures
Inside The ChipStep 1Challenge 1 — Electric Dough (Warm-up)
Play-Doh conducts electricity; clay does not. Make a few LEDs light to feel the difference before building a chip. Explore three circuit ideas:
- Series — one path for the current to flow.
- Parallel — several paths share the same power.
- Short circuit (avoid!) — Play-Doh touches Play-Doh, so the current skips the LED and it will not light.
Golden rule: always keep a wall of clay between the two LED legs, so the current is forced to travel through the LED rather than around it.
Step 2Challenge 2 — Make the Masks (one per layer)
A mask is a stencil of one layer’s wiring. You will make a separate carton-paper mask for each layer of your chip. For every layer:
- Draw & cut. On carton paper, mark where the conductor should go on this layer. Cut out or hole-punch the openings.
- Press through. Lay the mask on the clay (insulator) layer and press through the openings to mark the pattern.
- Carve (etch). Remove the clay where the openings are, leaving channels.
- Fill (deposit). Pack Play-Doh into the channels, flush with the surface — just like the copper-filled channels in the microscope photo above.
Then move up a layer. New layer = new mask. Add small Play-Doh vias (use tweezers) to connect this layer’s wiring down to the layer below.
Step 3Challenge 3A — Guided Build (with your instructor)
Start simple: one red transistor and one green transistor. Build the model shown below together with your instructor.
Guided build: a single red and a single green transistor, with blue, red, and green terminals.
The BLUE terminal is the shared / common terminal. The model should behave like this:
Connect the battery to… Result BLUE + RED The RED LED lights BLUE + GREEN The GREEN LED lights The red path and the green path must never touch — the clay keeps them apart.
Step 4Challenge 3B — Your Build (on your own)
Now scale it up: several red and green transistors, stacked across layers. Build the model shown below on your own team.
Independent build: multiple red and green transistors across stacked layers.
- Same rule: BLUE + RED lights all the reds; BLUE + GREEN lights all the greens.
- Wire the same-colour transistors together (in parallel) along each layer.
- Use Play-Doh vias to carry the signal between layers.
- Cut one carton mask for every layer.
- Keep a clay wall between the red and green wiring everywhere.
Test, fail, redesign — that’s engineering.
Step 5How Your Chip Works
Follow the current. Power leaves one terminal, runs through the Play-Doh interconnect, passes through an LED (transistor), and returns to the common BLUE terminal. Whichever colour you power is the only one that lights:
- Battery on BLUE + GREEN: current flows green-terminal → green wiring → green LED → blue common. Only green lights.
- Battery on BLUE + RED: current flows red-terminal → red wiring → red LED → blue common. Only red lights.
Why the clay matters: the insulator everywhere else blocks shortcuts. If the red and green Play-Doh paths ever touch, you create a short circuit — powering one colour would wrongly light the other, or nothing would light at all.
Step 6Helpful Hints
- Polarity: the LED’s longer leg is the + (positive) side. Match it to the powered terminal’s + side.
- Trim the legs: cut LED legs short so they stand in the shallow channels without tipping over.
- Carve deep, fill flush: make the channels fairly deep, then press Play-Doh in level with the surface, working from one side across.
- Vias: use tweezers to drop small Play-Doh clumps into the holes between layers, patting down and adding more as needed.
- Mask alignment: cut each mask a little larger than its layer so it is easy to line up.
- No shorts: a clay wall must separate the red and green wiring at every point.
- Even layers: a sandwich-bag circle laid over a layer helps you press the next layer down evenly.
Engineering Design Process
Work like an engineer. Move through these steps, and loop back as often as you need:
- Identify the problem and review the criteria & constraints.
- Research how real chips wire transistors together.
- Brainstorm possible layouts — sketch while you brainstorm!
- Choose your best design.
- Build a prototype, layer by layer.
- Test whether the right LEDs light.
- Redesign and try again until it works well.
Productive failure. If your LEDs don’t light at first, that’s expected. Troubleshoot, sketch the fix in your notebook, and try again. There is no single “right” solution — be ready to show off more than one.
Background Concepts
Transistors & Interconnections
- Transistor = a tiny switch. A chip has billions of them. In this lesson, each LED represents one transistor.
- Interconnects = the metal wires and vertical vias that connect those transistors. Metal lines run sideways within a layer; vias act like elevators between layers; local wiring links nearby transistors while global wiring spans the whole chip.
Transistors sit at the bottom; stacked metal layers (interconnects) wire them together. Right: local vs. global interconnects.
How Small Is It?
Real interconnects are built at the nanoscale — about a billion times smaller than we can see. As an illustration of just how tiny that is: more than a million interconnects could fit across a single human hair. We will build at “giant” size by hand, but the ideas are exactly the same.
Cross-section of a single human hair, seen under a microscope.
What Real Wiring Looks Like — and How It’s Made
Engineers don’t lay wires down by hand. They carve channels into an insulating layer and then fill them with copper — carve, then fill, one layer at a time. (This is called the damascene process.) Our model copies this idea directly: carve the clay with a mask, then fill the gaps with Play-Doh.
Real copper interconnects under a microscope. Top-right: metal-filled channels — the look you’re aiming for.
Vocabulary
- Conductor – A material electricity flows through easily. In our model: Play-Doh.
- Insulator – A material that blocks electricity. In our model: clay / plasticine.
- Transistor – A tiny electronic switch. A chip holds billions. Each LED stands for one.
- Interconnect – The metal wiring that links transistors to each other across the chip.
- Via – A vertical connection that carries a signal from one layer up or down to another.
- Layer – One level of the chip. Real chips stack many wiring layers on top of each other.
- Mask – A stencil of one layer’s wiring pattern, used to shape where the conductor goes.
- Etch (carve) – Removing material to leave channels in the desired pattern.
- Deposition (fill) – Adding conductive material into the channels (our Play-Doh filling).
- Short circuit – Two paths touch by mistake, so current skips the transistor and it won’t work.
- Nanoscale – A billion times smaller than we can see — the size real interconnects are built at.
- Semiconductor – A material (like silicon) that can act as both conductor and insulator — the basis of chips.
Reflect & Debrief
Discuss as a team, then as a class:
- How did your mask help you pattern a layer? What happened when it was misaligned?
- How do vias connect one layer’s wiring to the next?
- Why does the insulator matter? What happens if the red and green paths touch?
- How does your Play-Doh model compare to the real copper-wiring photo?
- Real interconnects are about a million times smaller. What gets harder at that scale?
- What would you change in your next redesign?
- How did your mask help you pattern a layer? What happened when it was misaligned?
Student Worksheet
Inside the Chip: Student Worksheet
Name: __________________________
Part 1: Meet the Chip
- What does each LED represent in this activity?
☐ A battery
☐ A transistor
☐ A wire
☐ A computer- What do the Play-Doh pathways represent?
- What is a via?
Part 2: Build & Observe
As you build your chip, record what happens.
Challenge 3A
Did your model work?
☐ Yes
☐ NoWhich LED lit up first?
☐ Red
☐ Green
☐ BothChallenge 3B
How many transistor LEDs did your team stack?
What helped connect one layer to another?
Part 3: Troubleshooting Like an Engineer
Circle any problems your team encountered:
☐ Layers did not line up
☐ Via was missing
☐ Wiring touched when it shouldn’t
☐ LED did not light
☐ Connection came looseHow did your team solve the problem?
Part 4: Think Like a Chip Designer
Why must the red and green pathways stay separated?
What might happen inside a real computer chip if connections were placed incorrectly?
Part 5: Reflection
What was the most surprising thing you learned about computer chips?
If you could redesign your chip, what would you improve?
Curriculum Alignment
Primary Anchor: Australian Curriculum: Science & Technologies (v9.0) — Years 6–8
AC9S6U03
Standard: Investigate the transfer and transformation of energy in electrical circuits, including the role of circuit components, insulators and conductors.
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Active Fulfillment: Students evaluate the electrical conductivity of physical materials, using Play-Doh as a conductor (to map interconnect wiring) and non-conductive clay as an insulator (to prevent short circuits) to successfully light up a grid of LED “transistors.”
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Auditable Evidence: A functioning, multi-layered microchip prototype demonstrating insulated, active electrical pathways without short circuits.
AC9TDE8K02
Standard: Analyse how force, motion and energy are used in combination with materials, systems, components, tools and equipment to create designed solutions.
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Active Fulfillment: Students simulate the industrial semiconductor fabrication “carve-and-fill” manufacturing process, using physical masks to selectively layer conductive and insulating materials to build a structured microchip model.
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Auditable Evidence: A completed, step-by-step physical engineering log documenting the multi-layer fabrication steps, circuit mask templates used, and electrical troubleshooting outcomes.
International Crosswalk (Secondary Frameworks)
Region Framework Code Mapping Alignment United States NGSS MS-PS3-3 Apply scientific principles to design, construct, and test a device that either minimizes or maximizes thermal/electrical energy transfer (specifically, using distinct materials to guide electrical current while preventing short circuits). United Kingdom National Curriculum (Key Stage 3) Design & Technology Select from and use a wider, more complex range of materials and components, taking into account their properties (understanding the physical electrical constraints of semiconductor -
Related Engineering Fields and Degrees
Additional Resources
- Wafer to chip video
