Lesson Plan

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Lesson Plan
Grade: Date: 18/01/2026
Subject: Physics
Lesson Topic: Draw and use ray diagrams for the formation of a real image by a converging lens
Learning Objective/s:
  • Describe the principal components of a converging lens (principal axis, optical centre, focal points).
  • Construct accurate ray diagrams using the three principal rays to show a real image.
  • Apply the thin‑lens formula to calculate image distance and magnification for objects placed beyond the focal length.
  • Explain why the resulting image is real, inverted and can be projected onto a screen.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Convex (converging) lens set
  • Ruler and graph paper
  • Worksheet with practice questions
  • Laser pointer (optional for demonstration)
 Introduction:

Begin with a quick visual of a camera lens focusing light to capture a clear picture, asking students what they notice about the image formation. Review prior knowledge of lenses and the principal axis. State that by the end of the lesson they will be able to draw a correct ray diagram and predict the image characteristics for a converging lens.
Lesson Structure:
  1. Do‑now (5') – Students sketch a basic lens diagram from memory and list the key parts; teacher collects for quick check.
  2. Mini‑lecture (10') – Review lens terminology, sign conventions, and the thin‑lens equation using the projector.
  3. Guided demonstration (10') – Teacher draws the three principal rays step‑by‑step on the board, highlighting how they intersect to form a real image.
  4. Pair activity (15') – Learners set up a converging lens, object, and screen; predict the image location, then construct a ray diagram on graph paper; teacher circulates to support.
  5. Worked example (10') – Solve the 30 cm object problem together, linking the diagram to the lens formula and magnification calculation.
  6. Exit ticket (5') – Each student writes one short answer: “If an object is placed 2 f from a converging lens, describe the image produced.”
Conclusion:

Summarise how the three principal rays guarantee the correct image position and why the image is real and inverted. Collect the exit tickets to gauge understanding, and assign the worksheet for additional practice drawing ray diagrams with varying object distances.