A Years 9–10 design project: a motor-driven lift where the gear ratio is chosen against the brief on the gears board, driven both ways through a motor driver, and the measured lift time compared with the model's prediction.
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Students will be able to
I can choose a gear ratio against a brief.
I can drive a motor both ways through a driver.
I can compare a model's prediction with a measurement and explain the gap.
Timing
About 4 to 6 lessons (around 250 minutes). Inquire part lesson · Develop 1 · Create 2–3 · Test and evaluate 1
Before class
Builds on Mechanisms › Gear up the winch and Power and motors. LEGO Technic or Meccano gears are the quickest real build; printed gears need the CAD pathway. A limit switch (a microswitch on a pin with INPUT_PULLUP) is the tidy stop; a timed stop is fine for a first version.
If you assess with MYP Design, the steps line up with the criteria:
A Inquiring and analysing: the brief, its criteria and constraints, and research into parts (Inquire).
B Developing ideas: a design specification, the circuit and code plan, and the test table written before building (Develop).
C Creating the solution: building it (in the simulator, then for real), following the plan and justifying changes (Create).
D Evaluating: testing against the specification, recording failures, improvements and impact (Test, Evaluate).
Otherwise, use the same four headings as a simple rubric: each step's reflect checks are the evidence list.
Running the lesson
Develop: ask what the model leaves out.
Test: five lifts, mean time, compared with the prediction.
The hard part (on purpose)
The gap between predicted and measured time feels like failure. Make it the point: engineers explain gaps.
When students get stuck
What you will see
A question to ask
The fix
The lift stalls.
What does the model say about margin with friction?
Choose the pair with more strength in hand.
Answers to the checks
Inquire: the brief: Sort each line of the brief: a criterion (what it must do, which you can test) or a constraint (a limit you must work within)? Lifts 450 g by 1 m → Criterion; Takes 15 s or less → Criterion; Stops at the top and can lower again → Criterion; Motor 120 rpm, 200 g with no gears → Constraint; Gears from the kit: 8, 16, 24, 40 → Constraint; A motor driver and its own battery → Constraint Criteria are what you will test at the end; constraints decide what you are allowed to build with.
Choose the gears: Choose a gear pair that meets the brief, and lift with it.
8 → 24 (600 g, 15 s) or 16 → 40 (500 g, 12.5 s). With real friction, the one with more margin is safer.
Margin: Real gears lose about 10% of the force at each mesh. Which pair has more margin on strength? 8 → 24: 600 g against 450 g 600 × 0.9 = 540 g, still over 450. 16 → 40 drops to exactly 450 with no margin.
Which is evidence?: Your lift takes 17 s; the model predicted 15 s. What is the best explanation to give in your evaluation? The model ignores friction and the motor slowing under load; measure and say how much Real motors slow under load, and every mesh loses a little: the model's 15 s is a best case.
Stretch and support
Stretch: A compound gear train (two pairs) for a heavier load, and the constraint written as an inequality.
Support: The winch worked example beside the board, and a driver wiring diagram.
Exit ticket
Why might a real lift be slower than the gear model predicts?
The model ignores friction at each gear mesh and the motor slowing under load.
What each step is for
Inquire: the brief: Separating what the design must do (criteria) from the limits it works within (constraints) is the first move of any design brief.
Develop: plan before you build: Choosing the gear pair on the board makes the prediction; the real build then tests the model (no friction) against the world.
Create: build it: Building in the simulator first catches wiring and code slips cheaply; the real build then tests the design against the world.
Test: run your table: Running the test table written in Develop, and recording every result including failures, is the evidence for the evaluation.
Evaluate: against the brief: Judging the design criterion by criterion, with evidence from the tests, is what separates an evaluation from a description.
Where it leads
Other Years 9–10 projects: Two-motor drive base, Automated sorter.