| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Sketch, plot and interpret load-extension graphs for an elastic solid and describe the associated experimental procedures |
Learning Objective/s:
- Sketch a load‑extension graph for an elastic solid and label its key regions.
- Plot experimental data and calculate the stiffness constant and Young’s modulus.
- Explain the significance of the elastic limit, yield point and plastic deformation.
- Describe the step‑by‑step experimental procedure for obtaining the graph.
- Identify common sources of error and suggest ways to minimise them.
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Materials Needed:
- Metal wire or elastic rod specimen
- Fixed support and hook
- Set of calibrated masses (0.1 kg increments)
- Vernier calliper or micrometer ruler
- Graph paper or computer graphing software
- Calculator
- Projector and worksheet for recording data
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Introduction:
Begin with a quick demonstration of a spring stretching under weight to capture interest. Ask students what they already know about Hooke’s law and stress‑strain relationships. Explain that by the end of the lesson they will be able to produce and interpret a load‑extension graph and link it to material properties.
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Lesson Structure:
- Do‑now (5’) – Short quiz on Hooke’s law and stress/strain concepts (checks prior knowledge).
- Mini‑lecture (10’) – Review components of a load‑extension graph and formulas for stiffness constant (k) and Young’s modulus (Y).
- Demonstration (15’) – Teacher sets up the apparatus, measures original length and area, adds masses, and records extensions while students observe.
- Guided practice (20’) – Pairs repeat the loading steps, record data, and plot their own graphs on paper or using software.
- Analysis discussion (10’) – Groups interpret their graphs, identify elastic limit, yield point, and calculate k and Y.
- Error analysis (5’) – Identify possible sources of error and propose improvements.
- Exit ticket (5’) – Write one sentence summarising what the graph reveals about the material’s behaviour.
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Conclusion:
Recap the key features of the load‑extension graph and how they relate to material properties. Collect the exit tickets to gauge understanding, and assign a homework worksheet where students repeat the experiment with a different material and calculate its Young’s modulus.
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