A Years 9–10 design project: an automated sorter where a light sensor (or a trained model) decides and a servo flap acts, prototyped on the board, built, and measured for accuracy on a 20-item test set.
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Students will be able to
I can turn a sensor reading into a decision and an action.
I can measure accuracy on a test set.
I can explain why a design that passes its code tests may still sort badly.
Timing
About 4 to 6 lessons (around 250 minutes). Inquire part lesson · Develop 1 · Create 2–3 · Test and evaluate 1
Before class
Real light readings depend on room light and how the item passes the sensor; a shade or an LED lighting the item helps. The Servo library is a recipe until the class has met libraries. Links: Code › Train a recycling sorter (Teachable Machine) for the stretch route.
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: the code tests and the accuracy test answer different questions; ask which is which.
Test: someone else chooses the 20 items.
The hard part (on purpose)
Students treat 100% on their own five items as proof. Hold the 20-item test set back until Test.
When students get stuck
What you will see
A question to ask
The fix
Accuracy is poor.
What do the misses have in common?
Calibrate the threshold with real items, or shield the sensor from room light.
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)? Light items (400 or more) go to bin B → Criterion; The flap moves within 0.5 s → Criterion; At least 90% accurate on 20 test items → Criterion; Kit parts only → Constraint; USB power → Constraint Criteria are what you will test at the end; constraints decide what you are allowed to build with.
Prototype the decision: Here the LED stands in for the flap (on = bin B). Write the decision so all four tests pass.
if (level >= 400) flap to B (LED on), else A (off).
Accuracy: Your sorter puts 17 of 20 test items in the right bin. What is its accuracy, as a percentage? 85 17 ÷ 20 = 0.85 = 85%: under the 90% the brief needs.
Which is evidence?: Which is the strongest evidence that the design meets a criterion? A test from the table that set the input and recorded the expected result A planned test with a recorded result is evidence; everything else is a feeling.
Stretch and support
Stretch: The Teachable Machine route: compare its accuracy with the light sensor's on the same 20 items.
Support: A servo recipe card and a results table for the 20 items.
Exit ticket
Your sorter scores 18 of 20. Does it meet a 90% criterion?
Yes: 18 ÷ 20 = 90%, exactly the criterion.
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: Prototyping the decision against threshold tests, then planning a separate accuracy test with real items, separates "the code is right" from "the machine sorts well".
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, Lift.