PSLE Science: Control Setups and Alternative Explanations

eduKateSG PSLE Learner’s Guide · Vol 0110

A Primary 6 performance guide for Science. This guide teaches one precise examination job: Use the Control Setup to Identify Which Alternative Explanation Is Removed. It is written for learners first, with a practical route for parents and tutors near the end.

Do not rush from two correct details to one incorrect conclusion. First identify the relationship that makes the details belong together.

Current examination context. This guide is aligned to the PSLE subject formats examined in 2026 as published by the Singapore Examinations and Assessment Board. Always use your school’s latest instructions and the official paper directions on examination day.

Use this guide as a performance route

Read Chapters 1 to 4 before attempting the worked cases. Then cover the repair notes and solve each case aloud or on paper. Return after two or three days for the delayed-transfer round. The aim is not to remember these examples. The aim is to recognise the same reasoning job when the wording, numbers, diagram or situation changes.

Start by naming what the question is asking you to connect.
Use the relationship test before writing a connector, operation or conclusion.
Explain one worked case without looking at the repair.
Practise a mixed case after a delay.
Finish with the exam-control checklist, not with another rereading.

This volume does not replace specialist topic teaching. Use it to control performance at the point where knowledge must become an answer. For deeper teaching, follow the subject-owner link in Chapter 13.

Chapter 1: The exact job

A control setup is not merely the setup labelled control. Its reasoning job is to show what happens when the tested factor is absent or unchanged while relevant conditions are kept comparable. The comparison removes one alternative explanation. The method is to name the tested factor, name the measured result, identify the matched conditions, and state exactly which rival explanation becomes less plausible. A control strengthens a conclusion; it does not prove that every other possible factor has been eliminated.

The important shift is from recognition to control. Recognition says, “I have seen something like this.” Control says, “I can name the relationship, show why it fits, reject a tempting alternative and keep the conclusion inside the evidence.” PSLE questions often change the surface features while preserving the reasoning job. A learner who depends on remembered wording may freeze. A learner who understands the mechanism can rebuild the answer.

Use a four-part frame: objects—what two things are being connected; relationship—how they are connected; evidence—which detail makes that connection defensible; and scope—how far the conclusion may travel. If one part is missing, the answer may sound fluent while remaining logically weak.

Chapter 2: The learner’s move sequence

Move 1. Name the question being tested before describing either setup.
Move 2. Identify the one intended difference between test and control.
Move 3. List the important conditions that must remain comparable.
Move 4. State the responding variable in observable or measurable terms.
Move 5. Compare results, not labels.
Move 6. Name the alternative explanation the control addresses.
Move 7. Limit the conclusion to the tested factor, organisms, materials and conditions.

Practise the moves slowly until the order becomes stable. Speed should arrive by compression, not by skipping. During an examination, the full routine may take only a few seconds because each move has been rehearsed. During learning, say the moves in full so that a teacher or parent can diagnose the exact point where the reasoning changes direction.

Chapter 3: Why capable learners still lose marks

Many errors here are not failures of effort. They are category errors: the learner knows the details but assigns the wrong job to one of them. The repair is therefore more precise than “be careful”. Name the mistaken relationship, replace it with the legal one, and test the new relationship against the question.

Misconception 1. Saying the control is the setup that does nothing. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 2. Assuming every unchanged condition is automatically well controlled. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 3. Explaining only the test setup and ignoring the comparison. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 4. Claiming the factor is the only possible cause. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 5. Treating different containers, durations or sample sizes as harmless. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 6. Using a no-treatment control when a fair comparison needs another baseline. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 7. Calling repeated trials a control. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.
Misconception 8. Writing a conclusion broader than the tested conditions. Repair it by returning to the objects–relationship–evidence–scope frame before adding any new information.

A useful error log records the wrong relationship, not only the wrong final answer. Write, for example, “I treated sequence as cause,” “I treated a changing difference as a fixed factor,” or “I treated repetition as a control.” A named error can be noticed in a new context. “Careless mistake” is too vague to guide the next attempt.

Chapter 4: Worked cases with diagnosis and repair

Worked case 1

Situation. Two identical plants receive equal light and water; one receives fertiliser and one does not.

Tempting response. The plant without fertiliser is useless because it has no treatment.

Repair. It shows growth under the same main conditions without fertiliser, addressing the claim that ordinary watering alone explains the extra growth.

Why the repair works. Compare the difference in growth, then limit the claim to these plants and conditions. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Independent check. Hide the repair and explain which word, number, comparison or observation carries the reasoning. Then change one surface detail. If your method still works, you are learning the job rather than memorising the case.

Worked case 2

Situation. A seed is placed on damp cotton while another is on dry cotton.

Tempting response. The dry setup controls temperature.

Repair. Its main role is to show what happens without available water; temperature must also be kept the same.

Why the repair works. Name the absent factor, not an unrelated condition. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 3

Situation. One circuit has a closed switch and another an open switch.

Tempting response. The open circuit proves the bulb is faulty.

Repair. It provides a comparison without a complete path. If only the closed circuit lights, the result supports the need for a complete circuit.

Why the repair works. Do not invent a component fault. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 4

Situation. Equal food samples are kept at 5°C and 25°C.

Tempting response. The colder sample is always the control.

Repair. Neither temperature is automatically a control; they are two levels of the manipulated variable unless a baseline is specified.

Why the repair works. Describe the comparison rather than relying on the word control. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 5

Situation. A pupil tests evaporation using equal volumes in a wide and a narrow dish.

Tempting response. The narrow dish is a control because it evaporates more slowly.

Repair. Both are comparison setups for exposed surface area. Other conditions must match.

Why the repair works. A fair comparison can exist without a no-treatment control. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 6

Situation. One leaf area is covered and another is exposed before an iodine test.

Tempting response. The covered part controls the iodine.

Repair. The covered area reduces light exposure, helping rule out the claim that starch appears equally without light.

Why the repair works. Keep the conclusion connected to light and starch formation. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 7

Situation. Two identical toy cars roll on rough and smooth surfaces from the same ramp height.

Tempting response. The smooth surface is the control.

Repair. They are comparison conditions for surface roughness. Same car and ramp height reduce alternative explanations involving starting energy.

Why the repair works. Explain which conditions were matched and why. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 8

Situation. A beaker with pond water and organisms is compared with pond water alone.

Tempting response. The water-only beaker proves organisms cause every change.

Repair. It helps show whether the measured change occurs without the organisms, but container and starting conditions must also match.

Why the repair works. State the specific measured change. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 9

Situation. A magnet is placed near iron clips; another identical pile has no magnet nearby.

Tempting response. The no-magnet pile controls the number of clips only.

Repair. It gives the baseline without the magnetic influence, while equal clip numbers prevent quantity from explaining the difference.

Why the repair works. One control setup can rely on several matched conditions. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 10

Situation. Three repeated test setups give similar results but there is no baseline.

Tempting response. Repeats are the control.

Repair. Repeats improve reliability; they do not reveal what happens without the tested factor.

Why the repair works. Separate repetition from control comparison. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 11

Situation. A clear bag and a black bag cover similar leaves.

Tempting response. The black bag is a perfect control for light.

Repair. Bag material may also alter temperature or airflow, so the comparison may introduce extra differences.

Why the repair works. Audit unintended changes before accepting the control. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Worked case 12

Situation. Medicine is tested on one group while another receives an identical-looking inactive tablet.

Tempting response. The inactive group proves the medicine works for everyone.

Repair. It helps address effects of expectation and the act of taking a tablet, but the conclusion still depends on sample and results.

Why the repair works. A control removes a specific rival explanation, not all uncertainty. The repaired response identifies the relationship rather than merely repeating both details. It also keeps direction intact: the first quantity or event is not silently exchanged with the second.

Chapter 5: Misconception diagnosis in real time

When an answer feels uncertain, do not restart the whole question immediately. Diagnose the smallest unstable step. Ask: Did I select the wrong pair of details? Did I name the wrong relationship? Did I reverse its direction? Did I use evidence that belongs to a different part of the question? Did I generalise beyond the tested or stated conditions? Each question points to a different repair.

Use the “because test” carefully. Read your answer up to the conclusion, add because, and supply the supporting relationship. If the words after because merely repeat the conclusion, the reasoning is circular. If they introduce information not found in the question, the answer is invented. If they name an exact comparison, mechanism or textual detail, the reasoning is likely becoming visible.

Next use the “could still be true?” test. Imagine that the first detail is removed. Could the second detail still occur? If yes, direct causation may be too strong. Imagine a different rule that fits the first example. Does it fail on the next example? If yes, your pattern rule was under-tested. Imagine the control produced the same result. Would the proposed factor still explain the difference? If not, the conclusion needs revision.

Chapter 6: Practice progression from supported to independent

Do not begin with twelve mixed difficult questions. Build control in stages. Stage one is classification: label relationships without writing full answers. Stage two is completion: fill the missing connector, operation or comparison. Stage three is repair: correct a tempting response and explain the error. Stage four is independent production. Stage five is transfer after a delay.

Round A — classification: take cases 1 to 4 and write only the relationship label.
Round B — direction: draw an arrow or comparison sign showing which way the relationship runs.
Round C — evidence: underline the smallest detail that supports the relationship.
Round D — repair: rewrite each tempting response using no more words than necessary.
Round E — variation: change the names, values, materials or setting while keeping the reasoning job.
Round F — mixing: place one case beside a different relationship and decide which method belongs.
Round G — explanation: teach the method to an imaginary classmate without reading the guide.
Round H — timed use: allow a short, realistic decision window, then complete the final check.

Transfer prompt 1. Rebuild this situation with one important surface change: Two identical plants receive equal light and water; one receives fertiliser and one does not. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 2. Rebuild this situation with one important surface change: A seed is placed on damp cotton while another is on dry cotton. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 3. Rebuild this situation with one important surface change: One circuit has a closed switch and another an open switch. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 4. Rebuild this situation with one important surface change: Equal food samples are kept at 5°C and 25°C. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 5. Rebuild this situation with one important surface change: A pupil tests evaporation using equal volumes in a wide and a narrow dish. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 6. Rebuild this situation with one important surface change: One leaf area is covered and another is exposed before an iodine test. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 7. Rebuild this situation with one important surface change: Two identical toy cars roll on rough and smooth surfaces from the same ramp height. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Transfer prompt 8. Rebuild this situation with one important surface change: A beaker with pond water and organisms is compared with pond water alone. Keep the same reasoning job, but alter a name, number, setting, material or order. Write one wrong answer that a hurried learner might choose, then write the corrected answer and identify the relationship that makes it correct.

Chapter 7: Delayed transfer that proves learning

Immediate success can come from short-term memory. Delayed transfer asks whether the method can be retrieved after the wording is no longer fresh. Close the guide. After forty-eight to seventy-two hours, solve four mixed prompts: one familiar case, one case with changed surface details, one case that uses a competing relationship, and one case from another subject. Mark the relationship before checking the final answer.

A strong delayed answer should survive three changes. First, the nouns may change. Second, the order of information may change. Third, irrelevant details may be added. If performance collapses, return to the smallest weak move rather than rereading everything. For example, practise only direction, only baseline choice or only control-versus-repeat classification.

One week later, use a blank-page retrieval check. Write the method, two common traps and one example from memory. Then compare with this guide. The differences show what is unstable. Correct them in a new colour and immediately use the repaired rule on a new question. Correction without renewed use often produces recognition, not durable control.

Chapter 8: Checking without simply repeating the first attempt

A useful check is independent of the first route. If you merely reread the answer with the same assumption, the same error may look correct twice. Check direction by reversing the sentence and seeing whether the meaning changes. Check a pattern rule against another transition. Check a scientific conclusion by naming the alternative explanation the comparison was meant to reduce. Check an English inference by separating what happened from why it happened.

Objects check: Did I connect the two things the question actually asks about?
Relationship check: Is this sequence, cause, comparison, change, evidence, condition, control or contrast?
Direction check: Have I reversed giver and receiver, cause and result, earlier and later, or factor and outcome?
Evidence check: Can I point to the exact supporting detail?
Scope check: Did I write all, always or only when the evidence supports that breadth?
Unit and label check: Are values, people, variables and textual references still attached correctly?
Answer check: Did I complete every requested part and then stop?

Chapter 9: Examination control under time pressure

In the paper, the method must be compact. Use a ten-second reset when a question produces two plausible answers. Stop writing. Box the requested outcome. Mark the two candidate details. Label the relationship in one or two words. Reject the option that changes direction, baseline, unit or scope. Then write the shortest complete answer.

If you remain uncertain, preserve marks by stating only what the evidence supports. A restrained answer is stronger than a dramatic explanation built from outside knowledge. In Mathematics, show the comparison that identifies the rule. In Science, name the changed factor and measured result. In English, attach the inference to an exact textual detail and avoid turning a possibility into certainty.

Do not spend unlimited time trying to rescue one relationship question. Mark it, move on, and return with a defined check. On return, do not reread passively. Perform one diagnostic action: test another transition, identify the connector, compare the control or rewrite the cause-and-result arrow. A specific check gives the second attempt a new route.

Chapter 10: A mini practice set

Mini-task 1. Read this situation: A pupil tests evaporation using equal volumes in a wide and a narrow dish. Decide which relationship must be named first. Explain why the tempting response—“The narrow dish is a control because it evaporates more slowly.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 2. Read this situation: One leaf area is covered and another is exposed before an iodine test. Decide which relationship must be named first. Explain why the tempting response—“The covered part controls the iodine.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 3. Read this situation: Two identical toy cars roll on rough and smooth surfaces from the same ramp height. Decide which relationship must be named first. Explain why the tempting response—“The smooth surface is the control.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 4. Read this situation: A beaker with pond water and organisms is compared with pond water alone. Decide which relationship must be named first. Explain why the tempting response—“The water-only beaker proves organisms cause every change.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 5. Read this situation: A magnet is placed near iron clips; another identical pile has no magnet nearby. Decide which relationship must be named first. Explain why the tempting response—“The no-magnet pile controls the number of clips only.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 6. Read this situation: Three repeated test setups give similar results but there is no baseline. Decide which relationship must be named first. Explain why the tempting response—“Repeats are the control.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 7. Read this situation: A clear bag and a black bag cover similar leaves. Decide which relationship must be named first. Explain why the tempting response—“The black bag is a perfect control for light.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mini-task 8. Read this situation: Medicine is tested on one group while another receives an identical-looking inactive tablet. Decide which relationship must be named first. Explain why the tempting response—“The inactive group proves the medicine works for everyone.”—is unsafe. Then produce a precise answer using the repair principle without copying the wording above.

Mark each mini-task with four points: one for the correct objects, one for the relationship, one for supporting evidence or computation, and one for controlled scope. A final sentence can be polished later; first make the reasoning legal.

Chapter 11: Guidance for parents and tutors

Ask the learner to explain the relationship before correcting the final sentence. Questions such as “What are the two things?”, “How are they connected?”, “Which detail proves that?” and “How far can that conclusion travel?” reveal more than “Why is this wrong?” Keep the conversation neutral. The aim is to inspect a reasoning move, not to judge intelligence.

Use short mixed sets rather than long blocks of nearly identical questions. Two related examples help the learner notice the mechanism; a third example with a competing relationship tests whether the learner can choose. Return to the job after a delay. Record whether the learner needed a prompt and which prompt unlocked the answer.

Praise a visible move: preserving direction, testing a second difference, naming what the control removes, or using cautious language when evidence is limited. General praise can encourage, but precise feedback teaches. If a subject-specific knowledge gap appears, route the learner to the relevant canonical hub rather than stretching this performance guide into a replacement textbook.

Chapter 12: Frequently asked questions

Is a control always untreated?

Often, but not always. It is the baseline needed to answer the specific question.

Are repeated trials controls?

No. Repeats test consistency; a control tests what happens without or under a baseline condition.

What must be the same?

Conditions that could otherwise affect the result, such as time, amount, material and starting state.

Can a control prove one factor is the only cause?

No. It can make a named alternative less plausible within the tested design.

How should I phrase a conclusion?

State that the results support the factor affecting the measured outcome under the tested conditions.

What if the control differs in two ways?

Then the result cannot be attached confidently to only one difference.

Why name the alternative explanation?

It shows the logical work performed by the control, not merely its appearance.

What is the final check?

Ask what would still be unexplained if the control produced the same result as the test setup.

Chapter 13: Your next route

Continue through the permanent PSLE Learning Guide for the wider sequence of learner-performance guides. For deeper subject teaching, use the Science Learning Hub.

This batch is designed as a connected route. Next, read Vol 0108, Vol 0109 and Vol 0111. WordPress may publish these dated URLs; the links are kept as stable base-slug routes and can resolve through the site.

Your completion test is simple: can you meet a new question, name the relationship before reaching for an answer, show the supporting detail or calculation, and keep the conclusion within its proper scope? If yes, move to a mixed paper. If not, return to the first unstable move and practise that move alone.

Reinforcement: twelve explain-and-transfer drills

Drill 1. Two identical plants receive equal light and water; one receives fertiliser and one does not. First, classify the relationship without solving. Second, explain why “The plant without fertiliser is useless because it has no treatment.” attracts a hurried learner. Third, use this repair principle: It shows growth under the same main conditions without fertiliser, addressing the claim that ordinary watering alone explains the extra growth. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 2. A seed is placed on damp cotton while another is on dry cotton. First, classify the relationship without solving. Second, explain why “The dry setup controls temperature.” attracts a hurried learner. Third, use this repair principle: Its main role is to show what happens without available water; temperature must also be kept the same. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 3. One circuit has a closed switch and another an open switch. First, classify the relationship without solving. Second, explain why “The open circuit proves the bulb is faulty.” attracts a hurried learner. Third, use this repair principle: It provides a comparison without a complete path. If only the closed circuit lights, the result supports the need for a complete circuit. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 4. Equal food samples are kept at 5°C and 25°C. First, classify the relationship without solving. Second, explain why “The colder sample is always the control.” attracts a hurried learner. Third, use this repair principle: Neither temperature is automatically a control; they are two levels of the manipulated variable unless a baseline is specified. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 5. A pupil tests evaporation using equal volumes in a wide and a narrow dish. First, classify the relationship without solving. Second, explain why “The narrow dish is a control because it evaporates more slowly.” attracts a hurried learner. Third, use this repair principle: Both are comparison setups for exposed surface area. Other conditions must match. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 6. One leaf area is covered and another is exposed before an iodine test. First, classify the relationship without solving. Second, explain why “The covered part controls the iodine.” attracts a hurried learner. Third, use this repair principle: The covered area reduces light exposure, helping rule out the claim that starch appears equally without light. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 7. Two identical toy cars roll on rough and smooth surfaces from the same ramp height. First, classify the relationship without solving. Second, explain why “The smooth surface is the control.” attracts a hurried learner. Third, use this repair principle: They are comparison conditions for surface roughness. Same car and ramp height reduce alternative explanations involving starting energy. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 8. A beaker with pond water and organisms is compared with pond water alone. First, classify the relationship without solving. Second, explain why “The water-only beaker proves organisms cause every change.” attracts a hurried learner. Third, use this repair principle: It helps show whether the measured change occurs without the organisms, but container and starting conditions must also match. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 9. A magnet is placed near iron clips; another identical pile has no magnet nearby. First, classify the relationship without solving. Second, explain why “The no-magnet pile controls the number of clips only.” attracts a hurried learner. Third, use this repair principle: It gives the baseline without the magnetic influence, while equal clip numbers prevent quantity from explaining the difference. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 10. Three repeated test setups give similar results but there is no baseline. First, classify the relationship without solving. Second, explain why “Repeats are the control.” attracts a hurried learner. Third, use this repair principle: Repeats improve reliability; they do not reveal what happens without the tested factor. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 11. A clear bag and a black bag cover similar leaves. First, classify the relationship without solving. Second, explain why “The black bag is a perfect control for light.” attracts a hurried learner. Third, use this repair principle: Bag material may also alter temperature or airflow, so the comparison may introduce extra differences. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

Drill 12. Medicine is tested on one group while another receives an identical-looking inactive tablet. First, classify the relationship without solving. Second, explain why “The inactive group proves the medicine works for everyone.” attracts a hurried learner. Third, use this repair principle: It helps address effects of expectation and the act of taking a tablet, but the conclusion still depends on sample and results. Fourth, create a different example in which the tempting response would actually become correct, and state what extra evidence, value or control would be needed. This final variation matters because it teaches conditions, not slogans.

How to Perform in PSLE | Learner’s Guide Vol 0110 | Science: Use the Control Setup to Identify Which Alternative Explanation Is Removed