Grade 12 · Week 13 · Thursday

Iterate and Verify an Engineering Redesign

Learning objective: Create a controlled three-trial engineering investigation and explain the difference between model optimization and physical validation.

45–60 minutes · Digital investigation · Browser-local evidence

Scientific reading

Turn an idea into an experiment

An engineer begins with criteria and a model, then changes inputs while holding other variables fixed. In the simulation, keep input 500 J and duration 5 s while changing useful fraction from 50% to 60% to 70%, and keep thermal fraction within the permitted leftover. Record the effect on useful energy and the pass/fail report.

Sensitivity is a mathematical relationship

At fixed E_input, useful energy changes by E_input×Δη, where Δη is expressed as a fraction. Raising useful fraction from 60% to 70% at E_input=500 J increases useful output by 50 J. Yet that increase alone does not describe how a real machine achieves the improvement. A better ratio can require entirely new physical components and introduce costs or other losses.

Check the energy flow after every revision

For any allowed combination of useful and thermal percentages, the other fraction is 100%−useful%−thermal%. The simulator prevents percentages summing above 100%. This makes the ledger close mathematically, but does not establish that a specific device can physically route energy into those exact categories.

Communicate design limits honestly

Students export three trials and a justified final recommendation. They should separately state one missing real-world constraint and one safe way a qualified engineer could measure performance with appropriate equipment. No mains disassembly, battery puncture, exposed electrical tests or unqualified physical prototypes are part of this curriculum.

Vocabulary

iteration
Cycle of testing and revising a candidate design.
sensitivity
Change in output resulting from a controlled change in input.
model constraint
Rule imposed on allowable simulated inputs.
verification
Check that a model or calculation meets its specified requirements.
validation
Check how well a model corresponds to real observations.

Worked example

E_in=500 J. Raise useful fraction from 60% to 70%: output rises from 300 J to 350 J. At thermal fraction 25% the other fraction changes from 15% to 5%; the total remains 500 J.

Label useful and other pathways, numerical units and assumptions.

Student science portfolio

Record three candidate runs and one refined design. State which requirements pass and describe what real experimental evidence would be needed before making a practical recommendation.

Local browser notes, portable by JSON export. No remote synchronization.

Daily · Four Practice Questions

Open-book formative practice and explanations. Reach 80% after corrections; supervised exams remain separate.