Crack the Code · Stage 4
Weeks 8–9 · Final design, circuits & electronics
Build a working circuit for your chosen alarm design — off the ThinkerShield, on a breadboard or soldered — and house it in an appropriate enclosure.
TE4-1DPTE4-2DPTE4-4DPTE4-PRO-01TE4-PRO-02TE4-ENG-01
Open this deck on the projector and press F for full-screen. N toggles speaker notes. The accompanying teacher guide is at /curriculum/crack-the-code/teacher/lessons/5.
Before this lesson:
- Inventory the electronic-component bins (LEDs, 220 Ω resistors, breadboards, jumpers, buzzers, switches, LDRs).
- Set up a soldering station with ventilation and safety glasses if that's in scope for your class.
- Pull up a working Fritzing diagram of the alarm circuit on the projector.
intention
2 min
🎯
Final design, circuits & electronics
Build a working circuit for your chosen alarm design — off the ThinkerShield, on a breadboard or soldered — and house it in an appropriate enclosure.
- Inventory the electronic-component bins (LEDs, 220 Ω resistors, breadboards, jumpers, buzzers, switches, LDRs).
- Set up a soldering station with ventilation and safety glasses if that's in scope for your class.
- Pull up a working Fritzing diagram of the alarm circuit on the projector.
task
30 min
🛠️
Today's work
- Edit the final design and present it as a working, tactile project, producing:
an IPO chart of the control system, a materials list, a production plan
with ongoing evaluation, and a working circuit that runs the code.
- Identify the circuit components in the workbook using the word bank; classify
each as a sensor, an actuator or another component.
- Record what each component is and its function; note the safety concerns for
each tool and piece of equipment.
- Choose a method of circuit assembly, assemble the circuit, and have the build
safety-tested.
- Support students to edit and present the final design as a tactile, working
project; presentation options include a video diary of the process and use at
home, or an oral/multimedia presentation of the design process.
- Explain the circuit components in the workbook (LED, resistor, diode, LDR,
potentiometer, push button, toggle switch, piezo buzzer, breadboard, jumper
leads, copper tape, battery power supply) and classify each as sensor, actuator
or other.
- Explain basic electronic circuit theory — the flow of electricity, the need
for a power source, what a resistor does, open vs. closed circuits (e.g. an LED
needs a 220 Ω resistor in series; the LED only conducts anode→cathode).
- Introduce the tools, equipment and safety concerns (e.g. long-nose pliers —
watch for pinched fingers); demonstrate methods of circuit assembly and the
safety concerns for each; follow WHS guidelines (ESIS); safety-test, record and
file. Suggested planning tool: Fritzing.
check
3 min
🤔
Quick check
- I can wire a circuit that runs my final code without the ThinkerShield.
- I can use LEDs with the correct series resistor, the correct polarity, and a stable power supply.
- I can present my project in a working enclosure with all connections protected and labelled.
- LED polarity — anode (longer leg, flat-side notch absent) to the positive rail; cathode to ground. If it doesn't light, flip it.
- Missing series resistor — an LED with no series resistor pulls too much current and burns out.
- Common ground — every component needs a path back to ground; a buzzer that won't sound is often missing its ground wire.
- Loose breadboard contacts — wiggle every jumper; intermittent contact masquerades as code bugs.
reflect
3 min
📝
Before you pack up
What was the hardest part of getting your circuit working off the ThinkerShield? How did you fix it?
- Working circuit on the breadboard (photograph or video).
- Schematic or Fritzing diagram for the final circuit.
- Materials list with quantities and source.
- Final enclosed project in its case.
- Safety check signed off by the teacher before power-on.
End of lesson 5
That's it.
Tomorrow / next lesson: Final evaluation.