| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: understand that internal energy is determined by the state of the system and that it can be expressed as the sum of a random distribution of kinetic and potential energies associated with the molecules of a system |
Learning Objective/s:
- Describe internal energy as a state function that depends only on the system’s current state.
- Explain how internal energy originates from microscopic kinetic (translational, rotational, vibrational) and potential energies of molecules.
- Apply the relation ΔU = Q − W to connect heat and work with changes in internal energy.
- Compare internal‑energy contributions for ideal gases versus real gases or condensed phases.
- Analyse the effect of phase changes on the potential‑energy component of internal energy.
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Materials Needed:
- Projector and screen
- Whiteboard and markers
- Printed worksheet with energy tables and practice problems
- Animated video showing random molecular motion and intermolecular “springs”
- Scientific calculators
- Clickers or online quiz tool for quick checks
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Introduction:
Begin with a quick discussion of everyday phenomena such as a steaming kettle and a refrigerator to hook interest. Recall students’ prior knowledge of the kinetic theory of gases and the first law of thermodynamics. State that by the end of the lesson they will be able to describe internal energy in microscopic terms, apply ΔU = Q − W, and distinguish ideal‑gas from real‑substance behaviour.
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Lesson Structure:
- Do‑now (5'): Students list examples where heat changes temperature versus changes phase; share responses.
- Mini‑lecture (10'): Review state functions and introduce the microscopic picture of internal energy with the suggested diagram.
- Guided derivation (10'): Walk through U = ∑(K_trans+K_rot+K_vib+V) and connect to degrees of freedom for different gas types; complete worksheet tables.
- Interactive simulation (8'): Play the molecular‑motion animation; students predict how increasing temperature alters kinetic and potential components (poll responses).
- Application problems (12'): Group work calculating ΔU for an isothermal expansion of an ideal gas and for vaporisation of water; discuss Q and W contributions.
- Summary checklist & exit ticket (5'): Quick quiz matching concepts to statements; collect for formative assessment.
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Conclusion:
Recap that internal energy is a state function composed of random microscopic kinetic and potential energies, and that its change is governed by ΔU = Q − W. Students complete an exit‑ticket summarising one real‑world implication of the concept. For homework, assign the textbook section on internal energy plus two practice problems on ideal‑gas and phase‑change calculations.
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