PSLE Learner’s Guide · Volume 0935
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A plane mirror forms a virtual upright image that appears the same perpendicular distance behind the mirror as the object is in front.
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. Measure from the mirror plane
- 2. Place the image symmetrically
- 3. Trace reflected rays
- 4. Explain virtual image position
- 5. Keep size and orientation separate
- 6. Predict movement
- 7. Control observer effects
- 8. Control the examination explanation
- 9. Worked examples
- 10. Independent practice
- 11. Delayed transfer
- 12. Family guidance and FAQs
CHAPTER 1 OF 12 · Back to contents
1. Measure from the mirror plane
Object and image distances are measured perpendicular to the mirror surface, not along a slanted viewing line. Mark the nearest point on the mirror before measuring.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
- Check the object point mirror plane normal and observer.
- Check real reflected rays and their backward extensions.
- Check equal perpendicular object-image distances.
- Check virtuality upright orientation same size lateral appearance viewpoint and measurement control.
CHAPTER 2 OF 12 · Back to contents
2. Place the image symmetrically
For every object point, place the corresponding image point the same perpendicular distance behind the plane. Joining those points reconstructs the image.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 3 OF 12 · Back to contents
3. Trace reflected rays
Light travels from the object to the mirror and reflects into the eye. The brain traces the diverging reflected rays backward in straight lines.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 4 OF 12 · Back to contents
4. Explain virtual image position
The backward extensions meet behind the mirror, but the light rays do not actually travel there. A screen placed at that apparent position cannot capture the plane-mirror image.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 5 OF 12 · Back to contents
5. Keep size and orientation separate
A plane mirror produces an image of the same size and upright orientation. The familiar left-right appearance concerns correspondence and viewpoint, not a smaller or upside-down image.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 6 OF 12 · Back to contents
6. Predict movement
If an object moves 10 cm closer to a fixed plane mirror, its image also appears 10 cm closer behind it, so the object-image separation decreases by 20 cm.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 7 OF 12 · Back to contents
7. Control observer effects
Changing the observer position changes which reflected rays enter the eye and what part of the image is visible, but not the geometrical object-image distance for a fixed object and mirror.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 8 OF 12 · Back to contents
8. Control the examination explanation
Draw the mirror line, construct equal perpendicular distances, trace at least two reflected rays or extensions, state virtual upright same-size properties and avoid placing real light behind the mirror.
Build the explanation by naming the object point mirror plane normal and observer and real reflected rays and their backward extensions. 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 equal perpendicular object-image distances and returning to virtuality upright orientation same size lateral appearance viewpoint and measurement control. 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: An object is 30 cm in front of a plane mirror. Image distance behind?
Controlled answer. 30 cm. Plane-mirror object and image distances are equal perpendicular to 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 object-image separation. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “30 cm” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 2: For the same case, object-image separation?
Controlled answer. 60 cm. Add 30 cm in front and 30 cm behind.
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. Do not answer the image distance. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “60 cm” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 3: The object moves 8 cm toward the mirror. How much does the image move?
Controlled answer. 8 cm toward the mirror behind it. The image remains symmetrically placed.
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 separation change. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “8 cm toward the mirror behind it” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 4: How much does object-image separation change after that move?
Controlled answer. It decreases by 16 cm. Both object and image move 8 cm toward the plane.
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 before and after. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “It decreases by 16 cm” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 5: Can the image be caught on a screen behind the mirror?
Controlled answer. No. It is virtual; real reflected rays do not meet behind 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. Contrast a real image. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “No” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 6: Why does the image appear behind the mirror?
Controlled answer. The eye traces reflected rays backward to an apparent source. Their extensions meet behind the plane.
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 dotted extensions. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “The eye traces reflected rays backward to an apparent source” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 7: Is the plane-mirror image upright?
Controlled answer. Yes. It has the same vertical orientation as the object.
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 upright from lateral appearance. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Yes” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 8: Is it the same size as the object?
Controlled answer. Yes for an ideal plane mirror. Plane-mirror magnification is one.
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. Do not infer size from apparent distance alone. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Yes for an ideal plane mirror” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 9: From where is object distance measured?
Controlled answer. Perpendicularly from the object to the mirror plane. A slanted eye path is not the object distance.
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 a normal. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Perpendicularly from the object to the mirror plane” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 10: Does moving the observer move the geometrical image?
Controlled answer. No. The fixed object and mirror determine the image 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. Visibility can still change. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “No” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 11: Repair: light rays pass through the mirror and meet behind it.
Controlled answer. Reflected rays stay in front; only their backward extensions meet behind the mirror. That is why the image is virtual.
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 solid and dotted ray styles. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Reflected rays stay in front; only their backward extensions meet behind the mirror” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 12: Repair: an object 20 cm from the mirror has image separation 20 cm.
Controlled answer. Its image is 20 cm behind, so object-image separation is 40 cm. Image distance and separation are different.
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. Label both distances. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Its image is 20 cm behind, so object-image separation is 40 cm” and invent a fresh prompt that would justify it for the same reason. Then change one decisive condition to create a near-nonexample. This reverse task checks whether the learner owns the boundary rather than merely recognising the original sentence.
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 point mirror plane normal and observer, real reflected rays and their backward extensions, equal perpendicular object-image distances, virtuality upright orientation same size lateral appearance viewpoint and measurement control. 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: What two ray types should a diagram distinguish?
Explained answer. Real reflected rays and imaginary backward extensions. They have different physical meanings.
Delayed transfer. Use solid versus dotted lines. 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: Can a small mirror show a full image of a distant object?
Explained answer. It depends on geometry and observer position. Image size is not the same as the visible portion.
Delayed transfer. Trace boundary rays. 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: What remains unchanged when the observer steps sideways?
Explained answer. The constructed image position for a fixed object and mirror. The rays reaching that observer change.
Delayed transfer. State the viewpoint effect. 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: Why is the word appears important?
Explained answer. It signals an apparent virtual source behind the mirror. No light actually originates there.
Delayed transfer. Use careful scientific language. 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: What does same distance mean?
Explained answer. Equal perpendicular distances on opposite sides of the mirror plane. It does not mean equal slanted paths to the eye.
Delayed transfer. Mark the normal. 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 nearest wrong shortcut?
Explained answer. Measuring from the observer or along a reflected ray. Image construction uses the object and mirror plane.
Delayed transfer. Rebuild with symmetry. 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 lateral appearance be described carefully?
Explained answer. Corresponding sides appear exchanged from the viewer’s perspective while the image remains upright. Avoid saying the image turns around physically.
Delayed transfer. Use labelled letters. 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. Draw the mirror plane, drop a perpendicular from each object point, mark an equal distance behind, trace reflected rays with backward extensions, and check virtual upright same-size properties. Separate image distance from object-image separation.
Delayed transfer. Construct a two-point 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.