PSLE Learner’s Guide · Vol 0355 · Forces, measurement differences and fair comparison
Find the exact decision this guide helps you make
This guide helps a Primary 6 learner interpret a spring investigation by separating total length from extension, calculating each change from its own original length and limiting conclusions to comparable trials. The short rule is extension equals stretched length minus original length; compare changes only under controlled conditions. You will learn the mechanism, see worked examples, repair common misconceptions, practise in stages and use a compact examination routine.
Choose a reading route
- Understand why the error happens
- Use the step-by-step method
- Study eight worked cases
- Build practice and delayed transfer
- Use the examination-control routine
- Guidance for parents and tutors
- Read the FAQs and choose the next route
This is an examination-performance guide, not a replacement for full topic teaching. Use the complete PSLE Learner’s Guide volume directory to move across this series, the PSLE Learning Guide for the wider sequence and the Science Learning Hub for deeper subject instruction.
For complete teaching, worked practice and topic progression beyond this performance decision, continue through the Science Learning Hub. This volume keeps a narrower job: it helps the learner recognise, execute and check one examination decision without competing with the wider topic owner. For a nearby performance routine that is already published, continue to Vol 0327 on flexibility and elasticity.
A careful note about the current examination year
This article is written for the 2026 PSLE preparation context. SEAB’s official 2026 formats page lists English Language as subject 0001, revised Mathematics as 0008 and revised Science as 0009. Format details can change, so confirm any paper-specific timing, component or administrative instruction with the current official SEAB 2026 source and your school. The reasoning routine taught here is deliberately broader: it strengthens how you read evidence, make a decision and check an answer.
Why this mistake happens
A ruler beside a spring usually shows its total length, but the effect being compared may be extension: the increase from the spring’s original unloaded length. Two springs can finish at the same total length yet extend by different amounts if they started differently. Conversely, a longer final spring need not have extended more. The safe analysis names the measurement, subtracts the matching baseline and checks that the force, spring identity and measurement method are controlled before making a causal claim.
The mind likes a fast label. A familiar word, operation, result or rule triggers an answer before the conditions have been checked. That shortcut sometimes works in easy practice, so it becomes a habit. In a demanding question, however, a nearby distractor preserves the surface pattern while changing one important condition. The learner then performs a correct-looking move on the wrong object. The repair is to slow only the decision point: identify what is being linked or measured, preserve its labels, test the conditions, and then continue at normal speed.
Think of the method as a chain with four locks. Object: what exact idea or quantity is under discussion? Relationship: how are the relevant parts connected? Condition: what must be true for the move to be valid? Claim: what is the strongest conclusion the evidence actually supports? A weak answer often skips from object to claim. A strong answer makes the two middle locks visible.
The one-line operating rule
Extension equals stretched length minus original length; compare changes only under controlled conditions. Say it before the first practice set. During timed work, shorten it to four cue words you can recall without stopping.
The step-by-step method
Step 1: Identify whether each reading is an original length, stretched total length or extension
Identify whether each reading is an original length, stretched total length or extension. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Step 2: Record the baseline for the same spring before the load is applied
Record the baseline for the same spring before the load is applied. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Step 3: Calculate extension as stretched length minus original length with one consistent unit
Calculate extension as stretched length minus original length with one consistent unit. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Step 4: Pair every extension with the force or load that produced it, preserving trial labels
Pair every extension with the force or load that produced it, preserving trial labels. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Step 5: Compare trials only when spring identity, starting condition and measurement method are controlled
Compare trials only when spring identity, starting condition and measurement method are controlled. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Step 6: State the observed relationship for the tested range and check whether the spring returned to its original length after unloading
State the observed relationship for the tested range and check whether the spring returned to its original length after unloading. Do this on the page, not only in your head. A brief arrow, label, unit, underline or condition note makes the decision inspectable. If you later find an error, you can repair the exact step instead of restarting the entire answer.
At this stage, do not decorate the answer with extra facts. Ask one diagnostic question: “What evidence would make this step wrong?” If you can name a possible failure, check it now. If the failure is absent, continue. This negative check prevents confidence from replacing proof.
Misconceptions to diagnose and repair
Misconception 1
Tempting move: Calling the stretched total length the extension. This feels efficient because it removes a decision. It is unsafe because the question may have changed the reference, unit, interval, definition or strength of claim.
Repair: return to the line, number, setup or statement that supplies the condition. Mark it with a short label. Then rebuild only the affected link. Keep all earlier work that remains valid. The purpose of checking is targeted correction, not anxious repetition.
Misconception 2
Tempting move: Subtracting one spring’s original length from another spring’s final length. This feels efficient because it removes a decision. It is unsafe because the question may have changed the reference, unit, interval, definition or strength of claim.
Repair: return to the line, number, setup or statement that supplies the condition. Mark it with a short label. Then rebuild only the affected link. Keep all earlier work that remains valid. The purpose of checking is targeted correction, not anxious repetition.
Misconception 3
Tempting move: Comparing different springs as though material, thickness and condition were controlled. This feels efficient because it removes a decision. It is unsafe because the question may have changed the reference, unit, interval, definition or strength of claim.
Repair: return to the line, number, setup or statement that supplies the condition. Mark it with a short label. Then rebuild only the affected link. Keep all earlier work that remains valid. The purpose of checking is targeted correction, not anxious repetition.
Misconception 4
Tempting move: Claiming a rule beyond the measured range. This feels efficient because it removes a decision. It is unsafe because the question may have changed the reference, unit, interval, definition or strength of claim.
Repair: return to the line, number, setup or statement that supplies the condition. Mark it with a short label. Then rebuild only the affected link. Keep all earlier work that remains valid. The purpose of checking is targeted correction, not anxious repetition.
Misconception 5
Tempting move: Assuming a spring remains elastic without checking whether it returns after the load is removed. This feels efficient because it removes a decision. It is unsafe because the question may have changed the reference, unit, interval, definition or strength of claim.
Repair: return to the line, number, setup or statement that supplies the condition. Mark it with a short label. Then rebuild only the affected link. Keep all earlier work that remains valid. The purpose of checking is targeted correction, not anxious repetition.
Eight worked cases
Worked case 1: Single extension
Scenario. A spring is 8 cm long before loading and 11 cm long with a load.
The tempting error. Reporting an extension of 11 cm. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. Extension is the change from baseline: 11−8. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. The spring extends by 3 cm. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Remove the load and record whether the length returns to 8 cm. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 2: Same final length, different starts
Scenario. Spring A changes from 6 cm to 10 cm; Spring B changes from 8 cm to 10 cm.
The tempting error. Saying both extend equally because both finish at 10 cm. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. A extends 4 cm; B extends 2 cm. Equal final lengths do not mean equal changes. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Spring A shows the larger extension in these trials. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Draw arrows from each final reading to its own baseline. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 3: Different final lengths, equal extension
Scenario. Spring P changes from 5 cm to 8 cm; Q changes from 9 cm to 12 cm.
The tempting error. Saying Q extends more because it is longer at the end. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. P extension=3 cm and Q extension=3 cm. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Their measured extensions are equal, although their total lengths differ. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Express both changes in millimetres and compare again. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 4: Unit mismatch
Scenario. Original length is 7 cm and stretched length is 95 mm.
The tempting error. Subtracting 7 from 95 without converting. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. Convert 7 cm to 70 mm, then calculate 95−70. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Extension is 25 mm, or 2.5 cm. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Convert the answer back to the other unit. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 5: One spring, increasing loads
Scenario. The same spring extends 1 cm, 2 cm and 3 cm under three increasing loads.
The tempting error. Claiming every future load will produce the same pattern. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. Within the tested conditions, greater tested load is associated with greater extension. The evidence does not establish unlimited behaviour. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. State the relationship only for the tested range. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Add a new safe teacher-provided trial rather than extrapolating without evidence. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 6: Different springs
Scenario. Two springs receive the same load but have different thicknesses and original lengths.
The tempting error. Attributing the difference solely to original length. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. Several spring properties differ. The comparison does not isolate one cause. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Describe the measured extensions but do not name a single causal property. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Redesign with identical springs while changing only the chosen factor. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 7: Return after unloading
Scenario. A spring is 10 cm originally, stretches to 14 cm and remains 11 cm after unloading.
The tempting error. Calling the entire 4 cm change elastic because the load was removed. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. It extended 4 cm under load but did not return fully to 10 cm. A 1 cm lasting change remains. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Report both the loaded extension and the final residual change. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Link to the separate elasticity guide for the return test. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Worked case 8: Table audit
Scenario. A table lists original length, loaded length and “extension,” but one row says 9 cm, 13 cm and 5 cm.
The tempting error. Trusting the printed extension column automatically. The response may contain relevant knowledge, yet it does not answer the precise decision because one label or condition has been lost.
Work the mechanism. Recalculate 13−9=4 cm. The row is internally inconsistent. Write the decisive evidence beside the step where it is used. This makes the reasoning readable to another person and prevents a later sentence from quietly changing the meaning.
Answer form. Correct the extension to 4 cm before comparing trends. Notice that the answer carries both the conclusion and the reason that licenses it. It is complete without becoming a list of everything you know.
Check. Re-read the command word, substitute the conclusion into the original situation and ask whether every noun, number and comparison still has the same referent or unit. If the answer is stronger than the evidence, narrow it.
Delayed transfer. Audit every derived column from the raw readings. Do this variation after a gap, not immediately, so retrieval rather than imitation drives the solution.
Practice progression: from recognition to transfer
Round 1: mark only
Use six short items. Do not answer them. Mark the object, reference, unit, interval, condition or rule that controls the decision. The goal is accurate noticing without the burden of full writing.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Round 2: explain the choice
Solve four items and add one sentence beginning “This is valid because…”. If the sentence merely repeats the answer, the condition is still hidden.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Round 3: repair a wrong answer
Take four plausible wrong answers. Identify the earliest faulty link, preserve the correct work and rewrite only what must change. This develops error diagnosis rather than answer copying.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Round 4: mixed questions
Mix this job with two older skills. Remove headings that reveal the topic. Decide which routine applies before solving. Selection is part of performance.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Round 5: timed set
Use a small timed set with a fixed check budget. Mark a cue at the decision point, finish the answer, then perform one positive check and one rejection check.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Round 6: delayed transfer
Return after two or three days with different surface details. Before seeing notes, write the one-line rule from memory and solve. Compare the new error pattern with the earlier one.
Record the result as one of four codes: N for noticing error, M for method error, I for interpretation error, and C for checking error. Practise the weakest code with a fresh item. Do not repeat an entire worksheet when only one decision needs repair.
Graded independent practice with explained answers
Practice 1: Foundation
Try it. A spring changes from 12 cm to 15 cm. Find its extension.
Open the answer and explanation after attempting the question
Answer. 3 cm.
Why. Subtract the original length from the loaded length: 15−12.
Check or transfer. Name the answer extension, not final length.
Practice 2: Equal finals
Try it. A changes 7→11 cm; B changes 9→11 cm. Which extends more?
Open the answer and explanation after attempting the question
Answer. A.
Why. A extends 4 cm while B extends 2 cm.
Check or transfer. Use each spring’s own baseline.
Practice 3: Equal changes
Try it. P changes 4→9 cm; Q changes 10→15 cm. Compare extensions.
Open the answer and explanation after attempting the question
Answer. They are equal at 5 cm.
Why. Both differences are 5 cm even though total lengths differ.
Check or transfer. Do not compare final readings alone.
Practice 4: Units
Try it. A 60 mm spring stretches to 8.5 cm. Find extension in millimetres.
Open the answer and explanation after attempting the question
Answer. 25 mm.
Why. 8.5 cm=85 mm; 85−60=25.
Check or transfer. Convert 25 mm to 2.5 cm.
Practice 5: Fair comparison
Try it. Two springs of different materials receive different loads. Can the material effect be isolated?
Open the answer and explanation after attempting the question
Answer. No.
Why. Material and load both differ, so one cause is not isolated.
Check or transfer. Keep the load and other spring properties controlled.
Practice 6: Delayed transfer
Try it. A spring is 6 cm initially, 10 cm loaded and 6.5 cm after unloading. State two changes.
Open the answer and explanation after attempting the question
Answer. Loaded extension=4 cm; residual change after unloading=0.5 cm.
Why. The two differences answer different questions and use the same original baseline.
Check or transfer. Explain why the spring did not fully return.
A compact practice log
- Question source and date
- Decision cue you marked
- Your first answer in one line
- Earliest wrong link, if any
- Corrected rule in twelve words or fewer
- Date for delayed transfer
- Whether the new item was solved without notes
A useful log is small enough to maintain. It should help you predict the next mistake, not become a scrapbook of completed pages.
Checking that tests meaning, not neatness
A check should have a target. First run a positive test: identify the evidence, calculation or condition that supports your answer. Then run a rejection test: name the closest tempting alternative and the exact reason it fails. This pair is more powerful than rereading the same line while hoping to feel certain.
Use a reverse check where possible. Reconstruct the original amount, replace a connector with its expanded meaning, map a conclusion back to the data, or apply the repaired rule to the apparent exception. Reverse checking exposes lost labels and unsupported leaps because the answer has to return to its source.
Stop when the check has answered a real question. Repeatedly changing a sound answer because it feels unfamiliar is not checking. If the object, relationship, condition and claim all remain consistent, keep the answer and move on.
Examination control
When time is tight, use the cue ORCC: Object, Relationship, Condition, Claim. Write only the smallest useful mark—an arrow, a unit, a time interval, a boundary or a qualifying word. The mark should prevent the known error without slowing the rest of the paper.
- Read the command word and identify the decision.
- Mark the object or quantity that must keep its identity.
- State the relationship or operation in plain language.
- Check the condition that makes it valid.
- Give the claim at the strength supported by evidence.
- Use one positive and one rejection check, then stop.
If you become stuck, do not produce a longer answer immediately. Shorten the task: write what is known, what must be decided and what condition separates the two best options. A precise partial structure often unlocks the next step and also makes any partial credit more defensible.
A seven-day delayed-transfer plan
- Day 1: learn the one-line rule and complete two worked cases with notes.
- Day 2: solve four short items without notes; classify errors by N, M, I or C.
- Day 3: mix two new items with two older PSLE skills and hide the topic labels.
- Day 4: explain one case aloud to a parent, tutor or imaginary learner in under two minutes.
- Day 5: complete a timed mini-set and use the ORCC marks only at decision points.
- Day 6: rest this skill or practise a different subject so memory has to consolidate.
- Day 7: attempt one unfamiliar transfer item, then write the smallest rule revision needed.
Success on Day 7 matters more than fluency immediately after reading. Delayed transfer shows whether you can retrieve the method, recognise its job under new surface details and control it without a model beside you.
Guidance for parents and tutors
Ask for the decision, not a performance speech. Useful prompts are: “What exactly are you deciding?”, “Which word, unit or condition controls it?”, “What is the closest wrong option?” and “How can you check without starting again?” These questions keep ownership with the learner while making thinking visible.
When an error occurs, locate its earliest point. Praise accurate diagnosis even before the final answer is corrected. If the learner repeatedly loses the same label, introduce one stable notation: arrows for reference, units beside remainders, interval brackets for rates, or boxes around claim conditions. Avoid adding several new routines at once.
Build variation gradually. Begin with clean examples, then add one plausible distractor, then mix the skill with older content, and finally delay the next attempt. A learner who succeeds only when the worksheet title names the method has learned recognition, not transfer.
Keep emotional temperature low. A surprising exception or remainder is information, not proof that the learner is “bad at” a subject. The practical question is which link changed. Once that link is named, practise a small set that isolates it and then return to mixed questions.
The independent-reader test
Before you call the skill secure, explain one solution to a reader who cannot see your thoughts. Name the starting information, the decision, the condition that controls it and the reason the rejected alternative fails. If the explanation depends on “you know what I mean”, a label is still missing. Add that label to the answer, then remove any sentence that does not help the reader follow the chain.
Next, cover the worked example and rebuild the method from a fresh prompt. Do not copy the surface details. Recover the sequence of decisions. This separates genuine control from familiarity with one page. A learner who can transfer the decision routine to new names, numbers or apparatus has a more dependable examination skill than a learner who can reproduce only the model answer.
Finally, compress the method without losing its safety condition. Write one sentence of no more than fifteen words, then test that sentence against an awkward case. If the short rule gives the wrong result, restore the missing condition. Good compression keeps the mechanism available under time pressure while the awkward case prevents the cue from becoming a careless shortcut.
A timed diagnosis drill
Set aside twelve minutes and choose three unfamiliar questions that could trigger this error. Spend the first minute identifying the decision in each question without solving it. Mark the object, relationship, condition and permitted claim. This preview is not wasted time: it prevents you from entering a long method before you know what the method must preserve.
Solve the three questions in the next eight minutes. After each answer, write one tiny prediction about what a correct answer should preserve: a reference word, a whole-number boundary, a pathway, a unit, a direction or an observable result. Then compare the finished answer with that prediction. If they disagree, repair the earliest link and keep the later work only when its meaning remains valid.
Use the final three minutes to classify the errors. A noticing error means the controlling detail was never marked. A method error means the right information was present but the wrong operation or reasoning chain was used. An interpretation error means the result was calculated or observed correctly but described at the wrong level. A checking error means the answer contained a detectable contradiction that the final audit missed.
Repeat the drill a week later with different surface details and without looking at the old corrections. Improvement is not merely a higher score. Look for a shorter pause at the decision point, fewer unnecessary restarts, more stable labels and a clearer reason for rejecting the nearest wrong answer. Those are signs that the performance routine is becoming portable.
Frequently asked questions
What is extension?
The increase in length from the original unloaded length.
What is the formula?
Extension = stretched length − original length.
Why can final length mislead?
Different springs may start at different lengths.
Can I compare two different springs directly?
You may compare observations, but causal claims need relevant properties controlled.
Why check after unloading?
Return toward the original length is evidence about elastic behaviour.
Can I extend a trend beyond the data?
Not safely without more evidence; state the range tested.
What unit should I use?
Any consistent length unit, converted before subtraction.
What should I study next?
Use the Science Learning Hub for forces and investigations, then Vol 0327 for elasticity.
Your next route
Use this guide until you can state the rule, solve an unfamiliar case and explain why the closest alternative fails. Then return to the complete PSLE Learner’s Guide volume directory or move to a deeper subject route: the English Learning Hub, Mathematics Learning Hub, Science Learning Hub, or the full learning-hubs directory. Return to the PSLE Learning Guide when you want to place this skill inside a broader revision sequence.
Science now uses the same column discipline as Mathematics: every final reading must remain attached to its own baseline before the change can be compared.