PSLE Learner’s Guide · Volume 1063
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A smaller plane mirror may let fewer reflected rays reach the observer, so less of the object is visible. Under the plane-mirror model, it does not shrink the image itself.
Series routes: Use the complete PSLE Learner’s Guide volume directory, the original PSLE Learning Guide and the Science learning hub.
This guide uses original Primary 6 practice and does not predict a live question. Consult the SEAB PSLE formats examined in 2026 page for official information.
Open the full chapter index
- 1. Separate image from visible portion
- 2. Recall the plane-mirror properties
- 3. Change mirror size carefully
- 4. Do not invent magnification
- 5. Use observer position
- 6. Use object and mirror geometry
- 7. Reject the surface-location error
- 8. Draw boundary rays
- 9. Worked examples
- 10. Independent practice
- 11. Delayed transfer
- 12. Family guidance and FAQs
CHAPTER 1 OF 12 · Back to contents
1. Separate image from visible portion
The image is the apparent copy located behind a plane mirror. The visible portion is the part from which reflected rays actually enter the observer’s eye. These are not the same quantity.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
- Check the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location.
- Check reflection at the mirror that directs selected rays from the object into the observer’s eye.
- Check whether a change affects the image properties or only which rays and visible portion reach the observer.
- Check plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram.
CHAPTER 2 OF 12 · Back to contents
2. Recall the plane-mirror properties
In the primary science model, a plane mirror forms an upright virtual image of the same size as the object, as far behind the mirror as the object is in front.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 3 OF 12 · Back to contents
3. Change mirror size carefully
Reducing the mirror’s height or width removes reflecting area. Some rays that previously reached the eye may miss the mirror, so the observer may see less of the object or scene.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 4 OF 12 · Back to contents
4. Do not invent magnification
A flat mirror does not make the image smaller merely because the reflecting surface is smaller. Mirror size changes ray access and field of view, not the same-size image relation.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 5 OF 12 · Back to contents
5. Use observer position
Moving the eye changes which reflected rays can enter it. A person may see a different part of the same image even though the image properties have not changed.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 6 OF 12 · Back to contents
6. Use object and mirror geometry
Changing object distance moves the virtual image by the same perpendicular amount behind the mirror. It can also change ray paths and what a fixed mirror reveals, but it does not turn a plane mirror into a magnifying or diminishing mirror.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 7 OF 12 · Back to contents
7. Reject the surface-location error
The image is not formed on the mirror surface. The eye traces reflected rays backward and perceives the virtual image behind the mirror.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 8 OF 12 · Back to contents
8. Draw boundary rays
Mark the eye, the top and bottom of the object, and the mirror edges. Draw rays that reflect into the eye; the mirror boundaries show which parts can be seen.
Build the explanation by naming the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location and reflection at the mirror that directs selected rays from the object into the observer’s eye. A remembered keyword is not enough: connect the observation to the mechanism and identify what would have to change for the conclusion to change.
Repair the nearest misconception by checking whether a change affects the image properties or only which rays and visible portion reach the observer and returning to plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 9 OF 12 · Back to contents
9. Worked examples
Worked case 1: A full-length mirror is replaced by a shorter plane mirror. Does the person’s image become shorter?
Controlled answer. No. The image remains the same size; the person may see a smaller portion of it.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Draw rays from head and feet to the eye. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 2: What property changes most directly when mirror area is reduced?
Controlled answer. The range of rays that can reflect into the observer’s eye. Less reflecting area can limit the field of view.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Keep object and observer fixed. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 3: Is a plane-mirror image real or virtual?
Controlled answer. Virtual. Reflected rays appear to come from behind the mirror but do not actually meet there.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Contrast catching an image on a screen. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 4: An object is 40 cm in front of a plane mirror. Where is its image?
Controlled answer. 40 cm behind the mirror. Object and image have equal perpendicular distances from the mirror.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Find the object-image separation. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 5: Does halving mirror width halve image width?
Controlled answer. No. Mirror dimensions do not set the plane mirror image magnification.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. State what may be less visible. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 6: A learner sees only her face in a small mirror. Is the rest of the image absent?
Controlled answer. No. The mirror-eye geometry allows rays from only part of her body to reach her eye.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Move the mirror or eye and reconsider. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 7: Can moving the observer change what is visible?
Controlled answer. Yes. Different reflected rays reach a new eye position.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. State which image properties remain fixed if the object stays fixed. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 8: If the object moves 10 cm closer to the mirror, what happens to the image?
Controlled answer. It moves 10 cm closer to the mirror on the virtual side. The equal-distance rule still applies.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Check total object-image separation. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 9: Repair: A small mirror forms a miniature image.
Controlled answer. A plane mirror forms a same-size virtual image, but a small mirror may reveal only part of it. The claim confuses image size with visible portion.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Use boundary rays as evidence. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 10: Repair: The image lies on the mirror.
Controlled answer. The virtual image is perceived behind the mirror at the same perpendicular distance as the object is in front. The surface is where reflection occurs, not where the virtual image is located.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Extend reflected rays backward. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 11: Why can a small mirror still show an entire distant object?
Controlled answer. The required reflected rays may fit within the mirror and enter the eye. Apparent extent and ray geometry matter, not a simple mirror-object size comparison.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Avoid claiming that any tiny mirror always works from every position. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 12: Does stepping farther from a wall mirror necessarily shrink the plane-mirror image?
Controlled answer. No. The image remains the same size as the person, although its apparent angular size and visible framing may differ.
Mechanism. Identify the exact relationship, apply the relevant rule and preserve every stated condition. A surface clue may be compatible with several explanations, so the answer must show what makes this case decisive.
Misconception repair. Do not turn partial evidence into complete proof. Name the closest wrong answer, identify its missing condition and explain why the observed evidence supports the narrower conclusion.
Transfer. Separate physical image size from appearance. Solve the altered case from the mechanism rather than copying the previous wording.
Explanation standard. A complete explanation names the observation, connects it to the rule and limits the conclusion to what follows. It should remain valid if decorative details are removed. If the explanation depends on the story topic instead of the decisive relation, rebuild it.
Audit. Recheck the object plane mirror observer eye positions mirror boundaries incident rays reflected rays and virtual image location, reflection at the mirror that directs selected rays from the object into the observer’s eye, whether a change affects the image properties or only which rays and visible portion reach the observer, plane mirror reflection incident ray reflected ray normal equal angles virtual image upright same size same perpendicular distance field of view visible portion observer position mirror size magnification ray path and diagram. Decide whether the evidence proves the conclusion or only supports a limited statement.
CHAPTER 10 OF 12 · Back to contents
10. Independent practice
Practice 1: Which law controls each reflection?
Explained answer. Angle of incidence equals angle of reflection. Both angles are measured from the normal.
Delayed transfer. Draw the normal at the reflection point. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 2: A ray from the foot misses the lower mirror edge. Can that ray show the foot to the fixed eye?
Explained answer. No. Without striking the mirror at a suitable point, it cannot be reflected into that eye.
Delayed transfer. Move the eye and retest with a new ray. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 3: Why should the eye be included in the diagram?
Explained answer. Visibility depends on reflected rays reaching the observer. A ray path ending elsewhere does not explain what that observer sees.
Delayed transfer. Add one boundary ray. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 4: What remains constant when only mirror height changes?
Explained answer. The same-size upright virtual-image relation and equal object-image distances. Only access to reflected rays changes in the ideal plane-mirror setup.
Delayed transfer. List the controlled variables. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 5: Can a crack or missing section block part of the view?
Explained answer. Yes. It removes reflecting points for some ray paths without shrinking the underlying plane-mirror image.
Delayed transfer. Distinguish obstruction from magnification. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 6: What is the best evidence that the image did not shrink?
Explained answer. Plane-mirror geometry gives unit magnification; ray tracing shows only the visible portion changed. Both the rule and paths support the conclusion.
Delayed transfer. Explain without relying on memory alone. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 7: How should an exam answer phrase the result?
Explained answer. The smaller mirror reflects fewer relevant rays into the eye, so less may be visible, but the plane-mirror image remains the same size as the object. This separates mechanism and image property.
Delayed transfer. Add equal-distance information only if asked. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
Practice 8: State the full method.
Explained answer. Identify object mirror and eye positions, recall that a plane mirror forms an upright same-size virtual image at equal perpendicular distance, draw incident and reflected boundary rays using equal angles, use the mirror edges to decide what reaches the eye, and distinguish visible portion from image size. The method predicts view without inventing magnification.
Delayed transfer. Apply it after a delay to a short mirror a narrow mirror a moved eye and a moved object. Cover the answer later and rebuild the chain.
Control question. Which exact condition does the nearest wrong answer miss? State it before checking.
Extension. Change one decisive feature while keeping the story similar. Explain why the conclusion now stays or changes.
Independent proof. Restate the answer without copying its wording. Your version must identify the evidence, the governing relationship and the boundary of the claim. Then write one fact that would be relevant but still insufficient on its own. This separates explanation from repetition.
Delayed comparison. Save this item beside the near-nonexample you created. On the next attempt, compare them before answering and point to the single feature that controls the difference. If more than one feature changed, revise the pair so the comparison stays fair.
CHAPTER 11 OF 12 · Back to contents
11. Delayed transfer
On day one, solve clear examples. On day three, mix examples, near-nonexamples and incomplete evidence. On day seven, solve without headings or a word bank. Delay reveals whether the method can be reconstructed independently.
Keep an error log for the first failed stage: reading, representation, rule, execution or checking. The earliest failure identifies the repair.
Interleave this skill with neighbouring ideas that share vocabulary. Classify each item only after naming the distinguishing condition.
In timed work, mark the relationship, apply the rule, write the conclusion and audit one condition. If checking changes the answer, record the overlooked feature.
Create a teach-back card with a near-nonexample on the front and the repaired mechanism on the back. Explain why the tempting answer fails.
Finish with one basic example, one boundary case and one transfer case. Supply explanations that a classmate can verify.
For a second delayed test, reverse the direction: start from a conclusion and invent evidence that would justify it, then evidence that would be insufficient. This exposes the boundary between relevance and proof.
CHAPTER 12 OF 12 · Back to contents
12. Family guidance and FAQs
Guidance for parents and tutors
Ask for the decisive condition before confirming the answer. Use prompts such as “What exactly happened?”, “Which stage or meaning is this?” and “What would prove it?”
Fade support from labelled examples to mixed questions and delayed open response. Independent retrieval after time and topic change is the target.
Praise precise claim control. Narrowing an answer when evidence is incomplete is scientific and academic strength.
Frequently asked questions
Should I memorise the rule?
Memorise the compact rule, then practise examples and near-nonexamples so the conditions remain visible.
What if two answers seem possible?
Return to the exact relationship and choose the option satisfying every stated condition without adding facts.
Why delay practice?
Immediate repetition may depend on the recent explanation; delay tests reconstruction.
How should an error be corrected?
Name the first failed stage and practise it with a changed example.
When is the skill ready?
When the learner can explain, apply and transfer it after a delay.
What is the final audit?
Check relationship, mechanism, claim strength and whole-question fit.
Next routes
Continue at the Science learning hub or return to the series directory.