| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Physics |
| Lesson Topic: Describe the use of converging and diverging lenses to correct long-sightedness and short-sightedness |
Learning Objective/s:
- Describe how converging lenses correct hyperopia and diverging lenses correct myopia.
- Explain the relationship between lens power (dioptres) and focal length for corrective lenses.
- Apply the thin‑lens formula to determine the appropriate prescription for a given refractive error.
- Interpret ray diagrams that show image formation with corrective lenses.
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Materials Needed:
- Projector and screen for displaying diagrams
- Whiteboard and markers
- Printed handouts with lens formula and ray diagrams
- Sample convex and concave lenses (or lens‑simulation app)
- Worksheet for prescription calculations
- Ruler or measuring tape for far‑point activity
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Introduction:
Begin with a quick demonstration: ask students to look at a distant object and describe any difficulty focusing. Recall the lens formula and the concept of focal length introduced earlier, linking it to how the eye focuses light. Today they will identify which type of lens corrects each refractive error and calculate the required dioptre value.
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Lesson Structure:
- Do‑now (5'): Students write differences between hyperopia and myopia on sticky notes; teacher collects for a quick check.
- Mini‑lecture (10'): Review thin‑lens formula, sign conventions, and lens power‑focal length relationship using projected slides.
- Demonstration (10'): Show ray diagrams for a converging lens correcting hyperopia and a diverging lens correcting myopia; discuss image shift onto the retina.
- Guided practice (15'): In pairs, students use sample lenses or a simulation to measure the far‑point of a mock eye and calculate required lens power; complete worksheet.
- Check for understanding (5'): Quick exit‑ticket quiz with two short questions – type of lens for each defect and the formula for power.
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Conclusion:
Summarise that converging lenses (+ dioptres) correct long‑sightedness while diverging lenses (‑ dioptres) correct short‑sightedness by moving the image onto the retina. Students submit an exit ticket stating one real‑world example of each lens type. For homework, assign a set of problems to calculate prescriptions for varied far‑point distances.
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