How to Perform in PSLE | Learner’s Guide Vol 0663 | Science: Oxygen Supports Combustion but Is Not the Fuel That Burns

PSLE LEARNER’S GUIDE · SCIENCE · VOLUME 0663

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The shortcut “oxygen helps things burn” must not become “oxygen is the fuel”. Combustion requires a fuel, oxygen and suitable ignition conditions. Each has a different role, and observations such as a glowing splint relighting must be separated from the inference.

• Diagnose — name the job before answering.
• Build — learn the core distinction.
• Compare — reject the nearest alternative.
• Interpret — keep labels and evidence aligned.
• Practise — delay and transfer.

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CHAPTER 1 OF 12

1. Diagnose the reader’s problem

The shortcut “oxygen helps things burn” must not become “oxygen is the fuel”. Combustion requires a fuel, oxygen and suitable ignition conditions. Each has a different role, and observations such as a glowing splint relighting must be separated from the inference.

Core mechanism. Label FUEL, OXYGEN and IGNITION. Fuel is the combustible material; oxygen supports the reaction; ignition supplies enough starting energy. A glowing splint relighting is standard evidence for oxygen because the gas supports combustion. It does not show that oxygen itself is flammable.

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CHAPTER 2 OF 12

2. Build the core distinction

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 1.1: candle burns in air

Answer: wax vapour is fuel; oxygen supports. Direct evidence: wax near the wick vaporises and reacts.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: wick alone is not the full fuel explanation. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 1.2: different candle sizes under equal jars

Answer: test is confounded. Direct evidence: fuel amount and wick may differ.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: not every duration difference is oxygen. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 3 OF 12

3. Find the decisive evidence

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 2.1: glowing splint relights

Answer: evidence for oxygen. Direct evidence: the observation precedes the gas inference.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: oxygen did not itself catch fire. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 2.2: equal candles under different jar volumes

Answer: larger jar may hold more oxygen amount. Direct evidence: concentration may remain the same in air.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: amount and concentration differ. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 4 OF 12

4. Compare the nearest alternative

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 3.1: splint burns brighter in oxygen

Answer: combustion is more vigorous. Direct evidence: fuel remains the splint material.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: brightness is not an exact concentration. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 3.2: lid smothers flame

Answer: oxygen access is limited. Direct evidence: one required condition is removed.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: fuel may remain. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 5 OF 12

5. Repair the common misconception

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 4.1: candle under jar goes out

Answer: conditions become unsuitable. Direct evidence: available oxygen falls while products accumulate.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: all air did not disappear. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 4.2: fuel valve closes

Answer: removing fuel stops combustion. Direct evidence: oxygen may remain.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: do not say oxygen was removed. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 6 OF 12

6. Work through a precise example

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 5.1: oxygen is called flammable

Answer: claim is inaccurate. Direct evidence: supporter and fuel are different roles.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: supporting combustion is not burning as fuel. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 5.2: spark starts mixture

Answer: spark supplies ignition energy. Direct evidence: reaction then releases energy.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: spark is not ongoing fuel. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 7 OF 12

7. Transfer to a changed context

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 6.1: wood burns in oxygen

Answer: wood is the fuel. Direct evidence: oxygen reacts in a supporting role.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: ignition is not continuing fuel. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

Worked case 6.2: smoke appears

Answer: smoke does not prove oxygen production. Direct evidence: visible products differ from invisible oxygen.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: use a gas test for identity. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 8 OF 12

8. Read tables, sentences or experiments

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 7.1: splint does not relight

Answer: oxygen evidence is absent. Direct evidence: one negative test does not identify every gas.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: do not guess carbon dioxide. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 9 OF 12

9. Explain rather than label

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 8.1: flame goes out in carbon dioxide

Answer: gas does not support this combustion. Direct evidence: the flame cannot continue.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: limit conclusion to the setup. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

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CHAPTER 10 OF 12

10. Practise independently

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Worked case 9.1: pure oxygen versus air

Answer: oxygen availability differs. Direct evidence: air is a mixture containing oxygen.

First classify the job of every important word, number, material or observation. Write the relevant labels before calculating or completing the sentence. This externalises the structure and prevents a familiar surface feature from controlling the answer.

Nearest misconception: air is not another name for oxygen. Test that alternative explicitly: state what it would predict, compare the prediction with the given cue, and reject it only when the mismatch is clear. This produces a reasoned correction rather than a memorised preference.

Now change one condition while holding the others fixed. Predict whether the answer should remain, change, become multiple or become indeterminate. Explain the update in one complete sentence that names both the changed condition and the mechanism it affects.

For independent practice, hide the labels and reconstruct them after a delay. Then produce a second example with different surface vocabulary but the same underlying relationship. A successful transfer preserves role, time, frequency, experimental condition, unit and scope.

Exam control: read the whole item, underline the decisive cue, mark what is given and asked, choose the rule only after its conditions fit, write the answer with its label or unit, test the nearest alternative, and narrow any claim that reaches beyond the evidence.

Self-explanation check: could another learner reproduce the decision from your reason alone? If the explanation merely repeats the answer, add the missing relationship. If it names a cue without showing why the cue matters, connect it to the rule and the rejected option.

• Classify before solving.
• Name evidence, not just the answer.
• Change one condition at a time.
• Explain the nearest rejected choice.
• Repeat after two days without prompts.

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CHAPTER 11 OF 12

11. Use delayed transfer and exam control

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Use a five-gate routine under time pressure: role, condition, operation or form, evidence, and final scope. Stop after the required answer is complete. If checking changes an earlier label, recheck every downstream step affected by that label rather than patching only the last line.

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CHAPTER 12 OF 12

12. Guide adults and choose next routes

This chapter applies the same mechanism from a different angle: classification, evidence, misconception repair, worked explanation, transfer and checking. Keeping the decision order fixed lets a learner handle unfamiliar wording without turning the guide into a list of isolated answers.

Frequently asked questions

Why explain a correct answer? It reveals whether the method will transfer. What if two answers look possible? Find the cue that gives them different jobs. Should I memorise every example? No; learn the condition that changes the result. How should adults help? Ask for the decision test, then schedule delayed retrieval.

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