LuduminaEN-10 · EN-U3 · Planned
Efficiency
Learning objectives
Calculate efficiency as fraction or percentage; H: justify a change increasing intended useful transfer.
8463 §§4.1.2.2 / 8464 §§6.1.2.2
DfE single-science pp.34–35 / Combined pp.29–30. Evidence checked 30 September–1 October 2026. Skills: WS1.4,3.6; MS1c,3b,3c.
Explanation
Efficiency compares the useful output for a stated purpose with total input. Thermal transfer may be useful for a room heater but unwanted for a lifting motor. Define the purpose and boundary before calculating the ratio.
Concepts, equations and units: η=E_useful/E_input=P_useful/P_input; dimensionless or %; system boundary and useful purpose specified.
Prediction, demonstration and game exercise
Predict, observe, explain
Measure useful lift output and input; separate dissipated energy from measurement discrepancy.
Planned learner game exercise
Compare machines for one declared purpose; H: choose lubrication/insulation improvements and predict consequences.
Independent practice
Calculate missing input/output and efficiency; explain why a heater can be useful despite thermal transfer.
Original practice example · Shared
A lifting system receives 200 J and raises the load’s GPE by 150 J. Find efficiency.
Show working and model answer
Working / reasoning
η = 150/200 = 0.75; percentage = 0.75 × 100.
Answer
0.75 or 75%.
Exit check and success criteria
Two ratios correct and output never exceeds input in the stated closed accounting; H justification passes.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
Efficiency equals power; thermal energy is always wasted; a percentage greater than 100 is plausible here.
Practical preparation
Optional efficiency investigation; revisits RP-P1/P2 data, not a new RP.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.