Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Physics
Lesson Topic: use the concept of efficiency to solve problems
Learning Objective/s:
  • Describe the principle of energy conservation and its relevance to real‑world systems.
  • Define efficiency and calculate it using the ratio of useful output to input energy.
  • Apply efficiency calculations to solve quantitative problems involving power, energy, and time.
  • Evaluate the reasonableness of results by checking energy losses and conservation.
Materials Needed:
  • Projector or interactive whiteboard
  • PowerPoint slides with formulas and diagrams
  • Worksheet with practice problems (including kettle example)
  • Calculator or spreadsheet
  • Thermometer and small electric kettle for a demo
  • Energy‑flow diagram handout
 Introduction:
Begin with a quick question: “If a device uses 100 J of electrical energy, how much mechanical work can we expect?” Connect this to prior learning on energy forms and the conservation law. State that today’s success criteria are to define efficiency, calculate it correctly, and use it to predict device performance.
Lesson Structure:
  1. Do‑now (5') – short quiz on energy forms and the conservation principle.
  2. Mini‑lecture (10') – introduce the efficiency definition, formula η = E_out/E_in, and show an energy‑flow diagram.
  3. Guided example (15') – work through the electric kettle problem step‑by‑step, students calculate useful energy, input energy and time.
  4. Collaborative activity (12') – groups solve a new problem (e.g., motor lifting a load) and present their calculations.
  5. Check for understanding (8') – click‑er questions targeting common pitfalls such as percentage‑to‑decimal conversion.
  6. Summary & exit ticket (5') – each student writes one correct efficiency calculation and one misconception they corrected.
Conclusion:
Recap the link between conservation of energy and efficiency as a practical tool for real‑world problems. Collect exit tickets to gauge individual understanding and assign a homework worksheet that extends the kettle scenario to a motor‑car example. Encourage students to reflect on how efficiency impacts engineering design.