IB DP Physics (2025) A3.6 Power & Efficiency Lesson Pack

IB DP Physics power and efficiency lesson pack, Topic A.3 Work, energy and power, SL and HL, first assessment 2025: power as the rate of doing work, P = Fv, and the efficiency of a device. Editable worksheet, 67-slide lesson deck, teacher key, worked solutions and a questions-only assessment, supplied as self-contained HTML plus colour and black-and-white PDF.

What students learn

• Power as the rate of doing work, and the watt as a joule per second.
• P = Fv, where F is the force that does the work, not the resultant force.
• Why a car at a steady speed still needs its engine, and what sets its top speed.
• Efficiency from energies or from powers, why it is never greater than 1, and where the rest of the energy goes.
• Percentage change, and how it differs from a change in percentage points.

IB skills (Tool 3: Mathematics, with Inquiry 3: Concluding and evaluating):

• Calculate and interpret percentage change (taught).
• Express derived units in terms of SI base units (practised).
• Derive relationships algebraically (practised).
• Interpret the gradient and the intercept of a graph (practised).
• Determine the effect of changing one variable on another (practised).
• Identify a systematic error and discuss its impact (practised).

What’s included:

• Student Worksheet - 18 pages
• Teacher Key - 30 pages
• Worked Solutions - 19 pages
• Assessment - 13 pages
• Lesson deck - 67 slides

Eight structured questions and five multiple-choice items: 64 marks across 37 parts, and eight figures. Your class works five questions, 32 marks, in the lesson, between two opening votes and a multiple-choice exit ticket. The votes are on a car cruising along a motorway and a farm pump swapped for a better one. Everything else goes home, including two exam-style questions and an eleven-mark data question in the Paper 1B pattern: a motor lifting a load, with its efficiency found from the gradient.

Sankey diagrams and energy density come in a later lesson. A margin box recaps W = Fs cos θ, and the teacher notes raise the guide’s linking question on rates of change. Worksheet and deck open in any modern browser with nothing to install, and the worksheet is fully editable. SI units, IB notation and IB command terms throughout. Suitable for grades 11-12 (ages 16-19) as a lesson, cover lesson, homework or revision.

Related resources:

• Mechanical Energy and Friction, the lesson before this one
• Work Done and Kinetic Energy, where W = Fs cos θ is taught
• Proportionality and Scaling, the skill pack on how one variable changes another
• The Units of a Quantity, the skill pack behind the unit work (free)

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