“Use two identical cups” is a small instruction with a substantial job. It usually helps keep container differences from confusing the comparison. Before replacing the missing cup, read the entire procedure and identify why the cups were meant to match.

The activity may compare two wrapping materials around containers. It may compare water loss under two positions. It may simply use cups to hold samples while the child observes something else. The same substitute can be important in one case and relatively unimportant in another.

A parent can ask, “What could this different cup change apart from the thing we are testing?” That question begins the Science. It moves the decision beyond whether the replacement looks convenient or whether the child can finish the worksheet tonight.

Check what “matching” means in this particular procedure. The instruction may require the same size, material and shape, with the same amount of water. Two cups from the same kitchen cupboard are not automatically equivalent. A tall narrow cup and a short wide cup may differ in ways relevant to the activity.

The tutor should also clarify whether the missing container is part of a demonstration or a comparison intended to support a conclusion. A demonstration can reveal a phenomenon without establishing which of two conditions caused the difference. A fair comparison needs more careful control.

Do not alter the worksheet silently. If a substitute is used with permission, record the change so the resulting observation can be interpreted correctly. The child should not submit a diagram of two matching cups when one was materially different.

This does not mean the activity is ruined. It means the apparatus instruction deserves thought. A missing cup can become a useful lesson in how scientific questions, procedures and evidence fit together, provided the adult helps the child make that connection.

The investigation question tells the family which differences matter. “Which wrapping slows cooling more?” is different from “Which container holds more water?” In the first question, matching containers help isolate the wrapping. In the second, the container difference may be the thing being investigated.

Ask the child to complete a simple sentence: “We are comparing ___ by observing ___.” If the child cannot identify either part, choosing new equipment is premature. The tutor can explain the purpose before the family spends time collecting materials.

For a wrapping comparison, the deliberately changed condition might be the wrapping material. The observed result might be water temperature after an agreed period. The containers, starting water amount and other relevant conditions should be kept comparable.

For a capacity comparison, the deliberately changed condition is the container. The observed result is how much water it holds under the agreed measurement procedure. In that case, using different cups is not automatically a flaw; the difference is part of the question.

The distinction prevents a common overgeneralisation: “Science always requires identical cups.” Science requires apparatus suitable for the question and comparisons that support the intended claim. Sometimes matching is essential. Sometimes deliberate differences are necessary.

Parents can ask the tutor to identify the reason for matching in plain language. “We want the wrapping to be the main difference” is clear. An unexplained instruction to “control variables” may leave the child remembering a phrase without understanding the actual setup.

Once the question is clear, examine the substitute against that purpose. Does it introduce a new material, opening, height, volume or measurement difficulty? Which of those could affect the observation?

The decision then becomes specific: accept the substitute for this job, change the plan with the tutor, or wait for matching equipment. That is a scientific decision the child can understand, rather than an adult rule about which cups are allowed.

A suitable replacement needs more than the same printed capacity. Two cups labelled 250 ml may have different openings, wall thicknesses and shapes. They can hold the same maximum amount while producing different conditions during an investigation.

Begin with material. A plastic cup, metal cup and ceramic mug are different objects. If the activity involves temperature, those material differences may matter. The child should not describe them as identical simply because both can hold 100 ml of water.

Next, consider shape and opening. A wide shallow container exposes water differently from a tall narrow one. In an evaporation investigation, the exposed surface is relevant. Equal water volume does not necessarily make the exposed surface equal.

Check size and fill level too. A small cup may be nearly full while a larger cup contains the same water amount at a lower level. Depending on the question, the available space, depth or ability to measure could affect the procedure.

Finally, inspect how measurements are made. Marks printed on a kitchen cup may not be precise measuring graduations. If the activity needs equal starting volumes, the assigned measuring tool and method matter more than guessing by eye.

A child-friendly comparison can use three headings: “same,” “different” and “might matter.” For example, “Same water amount; different cup material; material might affect cooling.” This keeps observation separate from interpretation.

Avoid claiming that every difference must have a large effect. The point is not to predict all possible outcomes confidently. It is to identify plausible influences before making a causal claim from an uncontrolled comparison.

The tutor can help decide which properties are relevant and how close a match is adequate for the learning activity. A parent should not need to determine experimental equivalence alone. The missing cup is a reason for clarification, not a test of the parent's scientific expertise.

Imagine the assigned activity uses two matching plastic cups, each containing the same water amount at the same starting temperature. Cup A has one wrapping material; Cup B has another. The child observes how the temperatures change under the teacher's agreed procedure.

Now Cup B is missing, and the family proposes a metal cup instead. The comparison has changed two things: wrapping and container material. If one setup cools differently, the result no longer isolates the wrapping as cleanly as intended.

This does not establish which factor caused the difference or how much each contributed. The metal cup may influence heat transfer, but the child should not invent a numerical effect or assume the observed difference must belong entirely to the cup.

A suitable response might be to obtain two matching replacement cups and apply the two wrappings to them, with the tutor's approval. Another response might be to pause the comparison while discussing the planned controls. A third might use one setup to observe cooling, while explicitly avoiding a claim that one wrapping was proven better.

The child can still write a useful explanation: “We could not compare the wrappings fairly because the cup materials were also different.” That is a statement about the procedure's limitation. It is not a confession that no Science learning occurred.

Ask which original conditions remain controlled. The water amount and observation time may still be matched. Recognising those successes helps the child understand that an investigation can have strengths and a particular limitation at the same time.

For a paper practice question, offer a proposed repair: two cups of the same material and dimensions, equal starting conditions, different wrappings. Ask the child what that repair is intended to improve. The answer is the ability to relate the difference in observation to the wrapping comparison.

Any physical activity involving warm water must follow the school's safe procedure and adult supervision. The learning decision about replacing apparatus should never become a reason to improvise a heating method at home.

Suppose the activity investigates water loss from containers placed under two specified conditions. The original plan uses matching cups with equal starting water amounts. One missing cup is replaced by a wide bowl.

The family may say, “Both contain 100 ml, so they are the same.” The water amount is matched, but the exposed water surface differs. That can matter to evaporation. If the setups also occupy different positions, the child cannot simply attribute a difference in water loss to position alone.

Explain the distinction using a familiar picture. The same amount of water can spread across a wide surface or sit more deeply in a narrow container. Equal volume does not guarantee equal shape, depth or exposed area.

The child should identify the intended comparison first. If the question is about exposed surface area, using different openings may be deliberate. If the question is about location while surface area is meant to remain comparable, the substitute introduces an additional difference.

A paper case can make this explicit. Setup A uses a narrow cup in one place; Setup B uses a wide bowl in another. Ask, “What prevents us from knowing whether the place alone explains the different water loss?” The answer points to the container opening as another relevant changed condition.

Do not supply invented experimental results as though the family measured them. If numerical values are used for discussion, label them as hypothetical data. Even an apparently neat pattern would not remove the design limitation.

A practical repair may involve obtaining matching containers or changing the question, with the tutor's agreement, to explore surface area rather than location. The repaired activity should be described according to what was actually compared.

For parents, this example shows why “it holds the same amount” is an incomplete replacement test. Ask what feature of the cup connects to the observed Science, then decide whether the substitute preserves that feature.

A child may be asked to compare an ice-related observation under two conditions using matching containers. If one container is missing, the family might substitute a thick mug for a thin plastic cup. That change can affect the thermal conditions around the ice.

Before proceeding, identify the original question. Is the activity about an insulating cover, the location, the container itself or simply observing a change of state? The relevant replacement decision depends on that purpose.

If the assigned comparison concerns two covers, changing the container as well adds an extra possible influence. The child should not claim that the covers alone explain any difference. If the comparison concerns container materials, the different containers may be appropriate, but other relevant conditions still need attention.

Equal-looking ice pieces may also differ in size or starting condition. The missing cup should not distract from those other controls. A tutor can help the child identify what must be comparable and how the endpoint will be observed.

An endpoint needs a definition. “The ice is gone” could mean no solid ice remains, not that all the resulting water has disappeared. The child should understand what is being timed or observed before comparing two outcomes.

For a written practice case, state the conditions clearly and ask for one limitation and one repair. A useful response might be, “Use matching containers so the container difference does not confuse the cover comparison.” If the cups themselves are the tested factor, that response would be inappropriate.

A physical ice observation should stay within the teacher's assigned safe procedure. There is no need to introduce hot surfaces or additional equipment to make the activity more dramatic. The Science is already present in the changing material and the conditions around it.

The parent decision becomes manageable: check the question, identify relevant extra differences and agree on a suitable replacement or a limited observation. Finishing quickly is less valuable than knowing what the activity can honestly show.

Some activities use a cup as a convenient holder rather than a factor that should influence the result. In a suitable magnetism activity, for example, the teacher may place several objects in a container before testing them individually. The cup is not necessarily part of the magnetic test itself.

If the objects are removed and tested according to the procedure, replacing the storage cup with another suitable holder may not affect the intended comparison. The tutor should confirm that the holder is merely organisational and that the testing conditions remain as assigned.

This example gives the child an important boundary. Not every equipment substitution invalidates an investigation. The question is whether the changed object affects the evidence or the procedure used to obtain it.

Now change the procedure. Suppose the magnet is meant to act through the wall of the container. The container's material and thickness can become relevant. A replacement that was harmless as a storage holder may be unsuitable when the cup sits between the magnet and the object.

Ask the child to explain the cup's job in each version. “It holds the objects before testing” differs from “The magnet is tested through the cup.” The same apparatus has a different relationship to the scientific question.

A parent can use this as a short paper discussion without performing an experiment. Draw or describe the two procedures and ask whether the holder needs to match. The explanation matters more than a memorised yes or no.

Use age-appropriate magnets and objects under the assigned supervision. Keep small objects and magnets away from younger siblings and do not improvise with unfamiliar equipment. These practical boundaries belong to the activity, not to a broad warning that Science is difficult.

The useful conclusion is encouraging. Sometimes a suitable substitute lets learning continue. A tutor should explain why it is suitable for that particular role, rather than accepting or rejecting every different cup on appearance alone.

A missing cup may be part of a measurement activity. The family should ask whether it is intended to contain a specified amount, collect water or serve as the measuring reference. Those roles require different checks.

If two containers only hold 100 ml measured with the same appropriate tool, a substitute may be acceptable for an activity whose question does not depend on container shape or material. If the cup itself supplies the volume reading, different markings or unclear graduations can change the measurement.

Consider a written case in which Cup A has clear millilitre graduations and Cup B has decorative lines with no stated units. Filling both to “the third line” does not establish equal volumes. The lines do not represent a common measurement scale.

A repair is to use the assigned measuring method to establish the starting amount, rather than treating unrelated visual marks as equivalent. The child can then record the amount with its unit.

There may also be a difference between capacity and actual volume. A cup capable of holding 250 ml does not contain 250 ml whenever it is used. Ask how much water is present in the activity, not merely what the packaging says the cup can hold.

For a simple practice question, state that one setup contains 100 ml and another 150 ml, although both cups have the same maximum capacity. If the investigation requires equal starting water amounts, the setup needs correction. Identical apparatus alone has not controlled the water amount.

This connects the cup decision to Mathematics without replacing the Science. Numbers and units help describe a scientific condition. The child should see why that condition matters to the comparison.

Parents can ask the tutor to confirm the measuring procedure before substituting equipment. A clear method protects the learning from avoidable guesswork and helps the child distinguish an observed or measured quantity from an assumption based on how full a cup looks.

In a school-aligned plant or seed activity, cups may provide space for the growing material and hold water or a supporting medium. Replacing one missing container can alter more than appearance. Size, drainage, depth and material may affect the conditions the child is meant to compare.

Begin with the question. If the activity compares two amounts of water, matching containers may help keep other conditions comparable. A substitute with drainage holes, when the original has none, changes how the water is retained. The amount poured in is not necessarily the amount remaining available.

If the activity compares container designs, the different container may be the intended factor. The child then needs to keep the plant material and other relevant conditions suitably comparable. Again, “different cup” is not automatically wrong; its role determines the decision.

Do not turn an unsuccessful seed observation into a confident conclusion about one changed factor. Seed condition, water, air and other relevant circumstances may need review. A missing or substituted cup is one feature to examine, not a complete explanation of every outcome.

A useful paper case states the difference explicitly: two matching containers were intended, but one replacement has holes at the bottom. Ask what additional condition may have changed and why the conclusion needs caution.

The child can propose a repair without conducting it: obtain matching containers, use the same assigned planting method and keep relevant starting conditions comparable. The tutor can assess whether that proposal fits the investigation.

Any real growing activity should follow the teacher's directions and ordinary hygiene. Children should not taste materials or treat an unknown plant specimen as safe simply because it appears in a learning activity.

For parents, the main lesson is that container differences can change what happens to water and growing material. Ask the tutor to explain the connection. That makes the substitute decision understandable rather than a rule about matching plastic objects.

When the substitute is unsuitable, the family still has options. The most direct option may be to obtain a matching cup from the original set or ask the tutor for a replacement. This preserves the assigned question with the least alteration.

Another option is to use two matching replacement containers, if the tutor agrees that they suit the procedure. Replacing both may restore comparability better than mixing an original cup with a very different household item. The starting amounts and other relevant conditions still need checking.

A redesigned activity can also be useful, but it should be named accurately. If the available containers differ in material, the tutor may decide to compare those materials instead of the originally assigned factor. The new question, procedure and conclusion should match one another.

Sometimes pausing the physical comparison is the most sensible choice. The child can still identify variables, interpret an original data table or explain a proposed repair. A Science lesson does not cease to exist because one piece of equipment is unavailable.

The least useful option is often to proceed silently, submit the altered activity as the original and hope the result looks familiar. That produces a completed page whose evidence is difficult to interpret.

Parents can ask for an educationally equivalent alternative rather than demanding that the child simply receive the expected result. An alternative might teach planning or interpretation while the practical comparison waits. Whether it is equivalent depends on the actual learning goal.

Avoid buying unnecessary equipment without clarification. The relevant question is what matching feature the procedure needs, not whether a more expensive kit must be better.

A good decision protects three things: the child's learning opportunity, the truthfulness of the record and the usefulness of the comparison. The tutor can help the family choose the simplest option that preserves those aims.

Repeated observations can help reveal variability in a procedure. They do not automatically remove a systematic difference between containers. If Cup A is plastic and Cup B is metal in every trial, repeating the activity preserves that additional difference.

A child might say, “We tested it three times, so it is fair.” The tutor should separate repetition from control. Repetition concerns how consistently a result appears under the procedure. Control concerns whether the comparison supports the intended explanation.

For the wrapping example, repeating the plastic-versus-metal setups may produce a consistent pattern. The child still cannot attribute that pattern confidently to wrapping alone, because the cup material remains different. Consistency does not settle which changed factor mattered.

This can be taught with a paper case rather than a physical experiment. State that the same two unequal containers were used repeatedly. Ask whether more trials would make them identical. The answer is no; the design needs an appropriate repair.

Repeating a repaired comparison can be useful when the activity and supervision permit it. The tutor should explain what the repetition is intended to reveal and how the conditions will be kept comparable.

Do not require a child to generate large sets of measurements merely to make an altered activity look scientific. More numbers cannot replace a clear question and a suitable procedure. Small, well-described observations may teach more than a long table whose conditions are unclear.

Parents can ask, “Would another trial address this problem, or do we need to change the setup first?” That question helps distinguish a recording uncertainty from an apparatus mismatch.

The child's next step should follow the limitation. If a reading was missed, a repeat might provide it under suitable conditions. If the compared setups differ in an unintended relevant way, the comparison itself needs attention. These are different scientific jobs.

If the tutor approves a substitute, the child's record should describe the equipment actually used. This protects the meaning of the observations and makes later feedback more useful. A simple note can be enough.

The note might say, “We used two matching replacement plastic cups because one original cup was missing.” If only one container changed, describe the relevant difference: “Setup B used a wider bowl instead of the matching cup.” Do not label it identical when it was not.

A diagram can show the changed feature, but the child does not need a decorative drawing of every household detail. Include information relevant to the question: material, opening, water amount or position, as appropriate to the activity.

Keep prediction, observation and explanation separate. The child may predict that the substitute will influence the result. The observation records what was actually seen or measured. The explanation discusses what the evidence can support and where the comparison remains limited.

If no measurement was taken, do not fill the result space with the expected answer from a lesson example. A predicted value and a measured value have different meanings. Ask the tutor what to submit when the practical cannot be completed as intended.

For a written practice activity, label hypothetical data as hypothetical. Numbers introduced to illustrate a limitation are not evidence that the family performed the investigation.

Parents can help with the record's clarity without rewriting the Science. Ask the child, “Could someone reading this tell what we used?” If the answer is no, add the relevant condition. The child should remain the author of their explanation.

An honest record can still show strong learning. Recognising that a comparison was altered and explaining the consequence may be more scientifically useful than presenting a familiar conclusion unsupported by the actual procedure.

The conclusion should answer the question the evidence can actually address. If the activity changed, the claim may need to become narrower. The child should not simply copy the conclusion that would have suited the original matched setup.

Suppose two wrappings were compared using different cup materials. A cautious conclusion might report that the two complete setups behaved differently under the observed conditions, while explaining that the effect of wrapping alone cannot be isolated from this comparison.

That is more precise than saying, “Wrapping A is better because its water stayed warmer.” The latter may assign the result to one factor even though another relevant factor also changed.

Do not swing to the opposite extreme and say nothing at all can be learned. The child may have observed temperature changing, identified a material difference or recognised a limitation in the design. Those are useful observations and reasoning steps, even if the original causal comparison is weakened.

For a paper case, ask the child to complete two sentences: “The evidence shows ___ about these setups” and “It does not establish ___ because ___.” This helps separate an observation from a broader explanation.

Keep wording age-appropriate. A Primary 4 learner can say, “The cups were different too, so we cannot tell whether the wrapping alone caused the difference.” The idea matters more than inserting sophisticated terms.

The tutor should help the child decide whether the activity still answers its intended question. If not, the next step may be a repaired comparison or an explanation of the limitation, depending on the assignment.

Parents can look for a conclusion that names the actual conditions and avoids claiming more than they support. That is good Science communication. It also gives the child a constructive way to finish an altered activity without pretending that the missing cup never mattered.

A parent can make the conversation straightforward: “One of the matching cups is missing. We have this substitute. Would its material and shape affect the comparison, and what would you like our child to do instead?” A photograph or clear description of the substitute may help.

The tutor's answer should connect the equipment decision to the Science. “Use it because the cup is only holding the objects before testing” is useful. “Use it because it looks close enough” may require further explanation if the container affects the measured outcome.

If a substitute is rejected, ask for a practical next step. Can both containers be replaced with a matching pair? Can the child complete a planning task? Is there a suitable original data set to interpret? Should the practical wait for a replacement?

The alternative should preserve the stated learning goal as far as possible. A child meant to learn measurement may need a measurement opportunity. A child meant to interpret evidence may work from a clearly labelled teaching data set. Those tasks are related but not identical.

Ask how the tutor will assess the resulting work. A substituted observation should not be compared uncritically with results from the original setup. The record should include the change so the tutor can interpret the child's explanation fairly.

The child can join the discussion by identifying the intended changed factor and the possible extra difference. This keeps the parent from carrying all the scientific reasoning while the child waits for a verdict.

A helpful tutor response reduces uncertainty and keeps the learning cheerful. It recognises that equipment can go missing and gives the family a route forward.

The decision need not become a complaint about the whole tuition programme. Start with the specific apparatus problem, the specific comparison and the agreed next task. Those details usually reveal whether the support is educationally thoughtful.

If the physical activity cannot continue, a short discussion can preserve learning without inventing results. The parent can help the child identify the question, the equipment's role and a possible repair. This is planning practice, not a claim that the experiment has been completed.

Ask the child to name the deliberately changed condition and the observation. Then show the available substitute and ask what additional difference it might introduce. Choose one relevant feature rather than listing every possible property.

For a cooling comparison, the child might identify different container materials. For an evaporation comparison, the opening may matter. For an object-sorting activity, the holder may not affect the test because the objects are removed before observation.

Next, ask for two possible actions. “Find another matching cup” and “Use two matching replacement cups with the tutor's permission” are practical proposals. “Write the expected result” is not an equivalent repair.

A simple prediction question can follow: “If the container changes as well, what becomes harder to explain?” The answer concerns which factor caused the difference, not a guessed measurement.

Keep the conversation short enough for the child to finish with a clear idea. It can be a useful bridge to the next lesson, but it should not become a full substitute curriculum delivered by the parent.

At the tutor review, bring the planning note and the original instructions. The tutor can see what the child understood and decide whether to return to the practical, teach a particular concept or provide a suitable paper case.

The wider Punggol Science Article Index contains the established routes for fair tests, variables and evidence. Use those broad owners for the larger subject picture. This focused guide helps the family decide what to do when one matched container is unavailable.

A child may produce a result that resembles the textbook example even after the apparatus changes. That resemblance does not establish that the activity was a valid test of the intended factor. Parents should look at the reasoning and conditions as well as the final pattern.

Ask the child to explain why the cups were meant to match. A useful answer identifies a relevant influence: “We wanted the wrapping to be different while the cups stayed the same.” That shows an understanding of the comparison's design.

Then ask what would change if the cup itself were being investigated. The child should recognise that different cups could become appropriate, with other conditions controlled. This checks whether the learner understands the principle rather than repeats “same cups” as a universal rule.

A fresh paper case can test the idea. Two matching containers with unequal water amounts are not automatically a well-controlled comparison if the water amount should match. Conversely, different containers used only to store objects before the objects are tested may not create the same problem.

The child's answer should refer to the actual procedure. “It is unfair because they look different” is less useful than identifying the relevant changed condition. The tutor can help move from visual similarity to scientific purpose.

Do not expect a perfect explanation immediately. The missing-cup decision may be the first time the child has considered why a procedural detail matters. A short, supported explanation can grow into a more independent one.

For parents reviewing tuition, ask for an example of how the tutor checked this understanding. A completed practical photograph alone cannot show what the child can explain.

The encouraging outcome is transferable judgment. Your child begins to ask whether a replacement affects the question, rather than waiting for an adult to declare equipment right or wrong. That is a useful scientific habit far beyond one cup.

As checked on 8 October 2026, SEAB's 2026 PSLE Science document assesses attainment in the 2023 Primary Science syllabus. Its objectives include understanding, application and scientific inquiry through interpreting information, evaluating methods and communicating reasoning. The examples in this guide support those broad habits; they are not a list of compulsory Primary 4 practical activities.

The child's actual school topic and current procedure should determine which example is suitable. Primary levels, topic sequences and Standard or Foundation routes should not be treated as interchangeable. Ask the teacher or tutor which scientific idea the assigned activity is intended to develop.

If the work forms part of an assessment, follow the school's instructions about apparatus, help and submission. A sensible home alternative may still require the teacher's approval before it can count for that task.

This article also does not establish that any particular tuition provider supplies practical kits, replacement equipment or a specific lesson format. Those arrangements should be verified with the responsible provider. The parent question concerns what good educational reasoning should look like when a matched item is missing.

Use existing subject routes to continue. The Science in Punggol study guide provides the wider Primary Science learning map, while the subject index links to more focused guides.

The practical answer remains manageable: identify the cup's role, examine whether the substitute changes a relevant condition and agree on a truthful next activity. A child does not need a perfect household laboratory to learn good Science. They need a clear question, suitable evidence and an adult who helps them understand the connection.

Useful next reading

For the wider subject route, visit the Science Article Index. Continue with the guide that fits the next learning decision:

The wider fair-test learning aim

Thermal insulation and cooling: the underlying concepts

Can we use any cup if both hold the same water amount?

Not automatically. Equal water amounts do not make materials, openings or shapes equal. Ask which container properties matter to the investigation. If the cups are only holders outside the actual test, a suitable substitute may be acceptable. If the container affects the measured outcome, closer matching may be needed.

Would using two replacement cups solve the problem?

It may restore comparability if the replacement pair matches appropriately and suits the procedure. Check with the teacher or tutor, particularly for assessed work. You still need to attend to water amount, starting conditions, position and the other relevant parts of the method. Matching cups alone do not guarantee a good comparison.

Should my child repeat the altered activity several times?

Only if repetition serves a clear purpose under the agreed procedure. Repeating an unintended container difference does not remove it. First decide whether the setup needs repair. Then consider whether further observations would help examine variability or strengthen the appropriate comparison.

Can we write the expected result when the practical cannot be completed?

Do not present an expected or predicted result as a measurement. Ask the responsible adult what alternative work is acceptable. The child may be able to write a prediction, explain the design or interpret a labelled teaching data set. Each should be described as the task actually performed.

What if the substitute produces the same result as the original lesson example?

The match does not prove the changed apparatus was irrelevant. Review the question and conditions. A result can look familiar while the explanation remains uncertain. Ask the child which factors differed and what claim the actual comparison can support.

Does one missing cup mean we should cancel the Science practice?

No. A planning discussion, paper case or observation may still be useful, depending on the learning goal. The tutor can help choose an alternative or arrange a replacement. The important distinction is between continuing to learn and claiming that the original practical comparison was completed unchanged.

How much detail should the child record about the replacement?

Include the features relevant to the question, such as material, opening, size or drainage. A simple sentence and clear label may be enough. The record should let the tutor understand what was used and interpret the observation. There is no need for an elaborate description of unrelated household details.

What should we do first tonight?

Put the original instructions beside the available substitute. Ask what the activity compares and which cup features might matter. Send the tutor a clear description if needed, then follow the agreed action. Your child can finish with a useful scientific decision rather than a hurried result built on uncertain conditions.