Lesson Plan

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Lesson Plan
Grade: Date: 25/02/2026
Subject: Physics
Lesson Topic: recall and use the first law of thermodynamics ∆U = q + W expressed in terms of the increase in internal energy, the heating of the system (energy transferred to the system by heating) and the work done on the system
Learning Objective/s:
  • Describe the sign conventions for heat (q) and work (W) in the first law.
  • Explain how to calculate heat transfer and work for a given system.
  • Apply ΔU = q + W to determine the change in internal energy in quantitative problems.
  • Identify and correct common sign‑related mistakes.
  • Relate ΔU to temperature change for an ideal gas using ΔU = nC_VΔT.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed worksheet with example problem
  • Scientific calculators (one per student)
  • Thermodynamics handout (sign conventions & key formulas)
  • PV‑diagram posters
 Introduction:
Imagine compressing a gas while heating it – what happens to its internal energy? Students will recall the conservation of energy and previous work on heat and work. By the end of the lesson they will be able to assign correct signs and compute ΔU for any simple system.
Lesson Structure:
  1. Do‑now (5 min): short quiz on heat and work sign conventions.
  2. Mini‑lecture (10 min): introduce ΔU = q + W, define each term and the A‑Level sign rules.
  3. Guided example (12 min): work through the aluminium block problem, students calculate q, W and ΔU.
  4. Group activity (15 min): new problem involving gas expansion/compression; students complete worksheet and present their sign choices.
  5. Check for understanding (8 min): clicker questions on common pitfalls; discuss answers.
  6. Summary (5 min): recap key points and formula sheet.
Conclusion:
We reviewed how heat, work and internal energy are linked by the first law and reinforced correct sign usage. For the exit ticket, each student writes the ΔU expression with appropriate signs for a specified scenario. Homework: complete the worksheet with two additional problems – one involving sensible heating and one involving a phase change.