Lesson Plan

• Describe the main parts of a converging lens and the sign conventions used in ray‑diagram analysis.
• Construct accurate ray diagrams that predict the position, nature and size of a virtual image formed by a converging lens.
• Apply the thin‑lens equation and magnification formula to calculate image distance and size, using correct sign conventions.
• Identify and correct common errors when drawing ray diagrams for virtual images.

• Whiteboard or interactive screen
• Projector for slide presentation
• Set of converging lenses (or a virtual‑lens simulation)
• Worksheets with practice object‑distance scenarios
• Rulers, pencils and erasers
• Scientific calculators

Begin with a quick recall quiz on lens terminology to activate prior knowledge. Explain that today’s focus is on how converging lenses produce upright, virtual images when the object lies between the lens and its focal point. State that students will be able to draw the diagram, use the lens formula, and check their work against a checklist.

1. Starter – Kahoot recall of lens terms (5 minutes).
2. Teacher modelling: step‑by‑step drawing of the principal axis, focal points and the three principal rays for a virtual image (10 minutes).
3. Guided practice: pairs draw ray diagrams for a given object distance; teacher circulates to give feedback (15 minutes).
4. Formula application: students calculate image distance and magnification using the thin‑lens equation, discussing sign conventions (10 minutes).
5. Common‑mistakes mini‑quiz: identify errors in sample diagrams and correct them (5 minutes).
6. Consolidation: complete the “Summary Checklist” on the worksheet to ensure all steps are covered (5 minutes).

Review the key steps for drawing a virtual‑image ray diagram and how the lens formula confirms the result. Ask each student to write one exit‑ticket answer describing the most common mistake they might make. For homework, assign a set of new object distances for which students must produce both a diagram and the corresponding calculations.