PSLE Learner’s Guide · Volume 1031
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Filtration works when insoluble solid particles are large enough to be retained by a suitable filter while the liquid passes through; a dissolved solute normally travels with the liquid through the filter.
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. Classify the mixture first
- 2. Trace what meets the filter
- 3. Name both products correctly
- 4. Explain dissolved particles carefully
- 5. Choose the desired product
- 6. Match filter and particle size
- 7. Use observations at the right strength
- 8. Control examination answers
- 9. Worked examples
- 10. Independent practice
- 11. Delayed transfer
- 12. Family guidance and FAQs
CHAPTER 1 OF 12 · Back to contents
1. Classify the mixture first
Filtration is suitable for separating an insoluble solid from a liquid. If the solid has dissolved to form a solution, ordinary filter paper does not separate that solute from the solvent.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
- Check the mixture components particle state solubility filter material pore size and desired product.
- Check the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained.
- Check whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step.
- Check mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion.
CHAPTER 2 OF 12 · Back to contents
2. Trace what meets the filter
A poured mixture reaches filter paper containing tiny pores. Liquid passes through, while insoluble solid particles larger than the effective pores are retained.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 3 OF 12 · Back to contents
3. Name both products correctly
The material left on the filter paper is the residue. The liquid collected below is the filtrate; it may still contain dissolved substances.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 4 OF 12 · Back to contents
4. Explain dissolved particles carefully
Dissolving disperses solute particles throughout the solvent. They do not remain as the same visible grains available for ordinary filtration and travel with the solution through the pores.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 5 OF 12 · Back to contents
5. Choose the desired product
If the goal is to collect sand from water, retain and dry the residue. If the goal is to recover salt from salt solution, filtration alone is unsuitable; removing solvent by evaporation or forming crystals may be required.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 6 OF 12 · Back to contents
6. Match filter and particle size
A filter works only when its effective pores retain the target particles while allowing the desired fluid through. A funnel without a filter merely guides flow and does not perform the separation.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 7 OF 12 · Back to contents
7. Use observations at the right strength
A clear filtrate shows that visible suspended particles were removed, not that every dissolved substance or microbe is absent. Appearance alone cannot prove purity.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. State why the tempting alternative is too strong, incomplete or about a different stage.
CHAPTER 8 OF 12 · Back to contents
8. Control examination answers
Name the mixture components, state which is insoluble, identify residue and filtrate, trace each component through the apparatus, and select a second method if the desired substance remains dissolved.
Build the explanation by naming the mixture components particle state solubility filter material pore size and desired product and the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained. 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 the evidence supports filtration alone or requires evaporation crystallisation or another separation step and returning to mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. 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: Can filter paper separate sand from water?
Controlled answer. Yes. Sand is insoluble and its particles can be retained while water passes through.
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. Name sand as the residue and water as the filtrate. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 2: Can ordinary filtration separate salt from salt solution?
Controlled answer. No. The dissolved salt passes through with the water.
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. Choose a method for recovering the salt. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 3: What is residue?
Controlled answer. Material retained on the filter. In a sand-water mixture, the sand remains on the filter paper.
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 use residue for the collected liquid. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 4: What is filtrate?
Controlled answer. The liquid that passes through and is collected. It may contain dissolved solutes even when it appears clear.
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 why clear does not mean pure. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 5: Repair: the filter removes every impurity from water.
Controlled answer. A suitable filter can retain certain insoluble particles, but dissolved substances may pass through. The claim must match pore size and particle state.
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 evidence needed before claiming purity. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 6: Why does a funnel alone not filter?
Controlled answer. It has no filtering barrier with suitable pores. The funnel changes direction of flow but does not necessarily retain particles.
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. Add filter paper and trace the paths. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 7: A muddy salt solution is filtered. What may remain in the filtrate?
Controlled answer. Water and dissolved salt. Mud particles may be retained, but dissolved salt passes through.
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. Design a second step to recover salt. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 8: A learner sees clear liquid after filtering. Is it pure water?
Controlled answer. Not necessarily. Dissolved substances can remain invisible in a clear filtrate.
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. Suggest a test or follow-up 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 9: What happens to insoluble chalk powder during suitable filtration?
Controlled answer. It is retained as residue. Its suspended particles do not pass through the effective pores.
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. Explain why dissolved sugar behaves differently. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 10: What happens to dissolved sugar?
Controlled answer. It passes through with the solvent. The sugar is dispersed in the solution rather than present as removable grains.
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. Recover it by removing some or all solvent under suitable conditions. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 11: Should the mixture be poured above the top edge of the filter paper?
Controlled answer. No. Liquid can bypass the filtering surface and carry particles into the filtrate.
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. Describe careful pouring below the edge. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. Decide whether the evidence proves the conclusion or only supports a limited statement.
Worked case 12: Why is the filter paper folded and placed in a funnel?
Controlled answer. The paper forms a supported barrier and channels filtrate into the container. The filter performs separation while the funnel supports and guides.
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 the jobs of the two pieces. 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 mixture components particle state solubility filter material pore size and desired product, the movement of liquid and dissolved particles through pores while suitable insoluble particles are retained, whether the evidence supports filtration alone or requires evaporation crystallisation or another separation step, mixture solution suspension solute solvent insoluble solid liquid filter paper funnel pore residue filtrate dissolve particle size pass retain evaporation crystallisation recovery fair test observation and conclusion. 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: If particles pass through one filter, what could be changed?
Explained answer. Use a filter with a smaller suitable effective pore size or another separation method. The method must match particle size and desired flow.
Delayed transfer. Avoid assuming any filter catches everything. 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: Which part should be dried if the aim is to collect sand?
Explained answer. The residue. Sand remains on the paper with some water and can be dried after filtration.
Delayed transfer. State a safe drying plan. 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: Which part is heated if the aim is to recover dissolved salt from the filtrate?
Explained answer. The salt solution in the filtrate, using an appropriate evaporation or crystallisation procedure. The salt is still in the liquid after filtering.
Delayed transfer. Do not discard the desired product. 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: Can filtration separate oil droplets from water in every case?
Explained answer. Not by the simple insoluble-solid filtration rule. Oil is a liquid, so another method suited to immiscible liquids is needed.
Delayed transfer. Classify the states before selecting apparatus. 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 observation supports successful sand-water filtration?
Explained answer. Sand is retained on the paper and a liquid filtrate is collected below. The observation matches the predicted paths.
Delayed transfer. Do not overclaim removal of dissolved substances. 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: Why is solubility more decisive than colour?
Explained answer. A coloured substance may be dissolved and pass through, while an insoluble colourless solid may be retained. Visible appearance does not determine the particle state.
Delayed transfer. Classify dissolved versus suspended. 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 fastest method-selection question?
Explained answer. Is the target solid insoluble in the liquid under these conditions?. A yes supports filtration; a dissolved solute needs another route.
Delayed transfer. Then identify which product is wanted. 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 every component and state, decide which solid is insoluble, match particle size to a suitable filter, trace retained residue and passing filtrate, remember that dissolved solute normally travels with the solvent, evaluate observations without claiming purity, and choose evaporation crystallisation or another appropriate second step when needed. The method connects classification, apparatus, particle path and product recovery.
Delayed transfer. Apply it after a delayed mixed separation problem. 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.