PSLE Learner’s Guide · Volume 0923
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Each light source creates its own blocked-light region; two sources can therefore produce two shadows whose darkness depends on whether the blocked regions overlap.
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. Treat each source as a separate path system
- 2. Predict the number of visible shadows
- 3. Explain partial darkness
- 4. Explain the overlapping region
- 5. Use switching as a diagnostic test
- 6. Track source movement
- 7. Control brightness and ambient light
- 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. Treat each source as a separate path system
For source A, trace rays past the opaque object’s edges to the screen. Repeat independently for source B. The object can block different paths from the two positions, producing two displaced shadow regions.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
- Check each light source object and screen.
- Check separate boundary-ray sets and blocked paths.
- Check single-source shadows overlap and illumination.
- Check source switching position brightness distance control and claim limits.
CHAPTER 2 OF 12 · Back to contents
2. Predict the number of visible shadows
With two distinct small sources and one object, up to two main shadows may appear. Their visibility depends on positions, screen, ambient light and whether the outlines overlap.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 3 OF 12 · Back to contents
3. Explain partial darkness
In a region where source A is blocked but source B still reaches the screen, illumination is reduced rather than absent. The shadow can look lighter than a region where both sources are blocked.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 4 OF 12 · Back to contents
4. Explain the overlapping region
Where the object blocks light from both sources, the screen receives less light from the pair and the overlap usually appears darker than either single-source shadow.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 5 OF 12 · Back to contents
5. Use switching as a diagnostic test
Turn off source A while leaving B on, then reverse. Each trial reveals which shadow belongs to which source and prevents a guess based only on left-right appearance.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 6 OF 12 · Back to contents
6. Track source movement
Moving one source changes only the shadow geometry associated with that source, provided everything else stays fixed. The other source’s shadow supplies a useful comparison.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 7 OF 12 · Back to contents
7. Control brightness and ambient light
A brighter unblocked source can make the region blocked from the weaker source appear less obvious. Shadow darkness is a comparison of received illumination, not a material property.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. 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
Name both sources, trace or describe each blocked path, identify overlap and state the switching evidence. Avoid saying the object produces or emits a shadow.
Build the explanation by naming each light source object and screen and separate boundary-ray sets and blocked paths. 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 single-source shadows overlap and illumination and returning to source switching position brightness distance control and claim limits. 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: Two small lamps shine on one ball and screen. How many shadows may appear?
Controlled answer. Up to two main shadows. Each source has its own blocked-light region.
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. Switch off one lamp at a time. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Up to two main shadows” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 2: Why can a single-source shadow look lighter when the second lamp is on?
Controlled answer. The second lamp still illuminates that region. Only one source is blocked 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. Identify the unblocked source. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “The second lamp still illuminates that region” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 3: Why is an overlapping region darker?
Controlled answer. Light from both sources is blocked. Less illumination reaches the overlap.
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. Compare with the side regions. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Light from both sources is blocked” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 4: Does the object emit two shadows?
Controlled answer. No. It blocks two sets of light paths.
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 arrows from each source. 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 5: What happens when lamp A is switched off?
Controlled answer. The shadow caused by A disappears while B’s remains. The test isolates one source.
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. Reverse the test. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “The shadow caused by A disappears while B’s remains” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 6: Can two shadows overlap completely?
Controlled answer. Yes, for some alignments. Their blocked regions can coincide on the screen.
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 one source sideways. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Yes, for some alignments” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 7: Can two lamps ever produce one visible combined outline?
Controlled answer. Yes. The two shadows may overlap closely or one may be too faint to distinguish.
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 one source from one outline alone. 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 8: Why label sources A and B?
Controlled answer. Labels keep the two ray systems separate. Unlabelled rays can be paired with the wrong shadow.
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. Colour-code on paper if allowed. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Labels keep the two ray systems separate” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 9: If source A moves left, must its shadow also move left?
Controlled answer. Not necessarily. Projection geometry can reverse the apparent direction on the screen.
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. Trace boundary rays rather than guess. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Not necessarily” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 10: What remains fixed in a fair source-position test?
Controlled answer. Object screen other source brightness and measurement rule. Changing several factors weakens the conclusion.
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. List the controlled variables. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “Object screen other source brightness and measurement rule” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 11: Why can ambient room light reduce contrast?
Controlled answer. It adds illumination to regions that would otherwise look dark. The blocked source paths are unchanged but visibility changes.
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. Darken the room consistently. Solve the altered case from the mechanism rather than copying the previous wording.
Reverse construction. Begin with the controlled answer “It adds illumination to regions that would otherwise look dark” 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 12: Does a darker shadow prove a larger object?
Controlled answer. No. Overlap brightness and source strength can change darkness.
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. Measure size separately. 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 each light source object and screen, separate boundary-ray sets and blocked paths, single-source shadows overlap and illumination, source switching position brightness distance control and claim limits. 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: How do extended sources affect edges?
Explained answer. They can create broader partial-shadow regions. Different points of one source are blocked differently.
Delayed transfer. Separate source count from source size. 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: What observation links one shadow to lamp B?
Explained answer. It remains when A is off and disappears when B is off. Switching supplies controlled evidence.
Delayed transfer. Repeat the trial. 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 is the screen required?
Explained answer. It makes differences in received light visible. The blocked paths exist in space, but the surface displays them.
Delayed transfer. Name another receiving surface. 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: Repair: two shadows mean there are two objects.
Explained answer. One object can form two shadows when two sources illuminate it. Shadow count also depends on source count and geometry.
Delayed transfer. Test by removing one 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.
Practice 5: Repair: the overlap is black because darkness is added twice.
Explained answer. The overlap receives less light because both sources are blocked. Darkness is not a substance being added.
Delayed transfer. Use illumination 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 6: What is the direct observation?
Explained answer. The number position and darkness of visible regions on the screen. The ray explanation is the mechanism.
Delayed transfer. Separate observation from inference. 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: What is the nearest wrong shortcut?
Explained answer. Counting shadows and immediately counting objects. Sources and overlap must also be considered.
Delayed transfer. Use switching evidence. 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. Trace each source separately, mark the blocked region, combine the two maps, predict overlap darkness and test by switching one source at a time. Control brightness positions and ambient light.
Delayed transfer. Design a two-lamp investigation. 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.