LuduminaWA-12 · WA-U4 · Planned
Lenses and image formation
Learning objectives
Construct convex/concave lens ray diagrams; distinguish real/virtual images; calculate magnification.
8463 §§4.6.2.5 / No Trilogy counterpart
DfE single-science pp.37–39 / Combined pp.32–33. Evidence checked 30 September–1 October 2026. Skills: WS1.2; MS3b,3c,5a,5c.
Needs firstWA-05
Explanation
A lens changes ray direction through refraction. Convex lenses can form real or virtual images depending on object position; a concave lens forms a virtual image. Magnification is a ratio, so object and image heights use the same units and the answer has no unit.
Concepts, equations and units: Magnification=image height/object height, no unit; both heights same units; principal focus, focal length m; convex real or virtual, concave virtual.
Prediction, demonstration and game exercise
Predict, observe, explain
Move an object through focal positions and show screen capture versus virtual viewing.
Planned learner game exercise
Position lenses to make a specified image; place principal rays and predict size/orientation before reveal.
Independent practice
Three ray-diagram cases and two magnification calculations.
Original practice example · Separate Physics
An image is 30 mm high and its object is 10 mm high. Find magnification.
Show working and model answer
Working / reasoning
Magnification = image height/object height = 30/10.
Answer
3, with no unit.
Exit check and success criteria
Correct image type/orientation for two cases and both ratios correct without units.
During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.
Misconceptions, practical links and mastery
Check these misconceptions
All lens images can be caught on a screen; magnification is measured in cm; ray lines are physical tracks.
Practical preparation
Optional lens/magnification investigation, AT4,8; not an additional RP.
Virtual preparation and revision only. Required hands-on activities and school records remain separate.
Proposed mastery
0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.