Science 6: Matter, Energy & Earth Systems — Midterm Exam worked answers
Student exam paperOriginal Grade 6 home-study paper with complete supplied scenarios, calculations, and scientific explanation. It samples the course and does not replace review of the investigation notebook.
20 questions · 60 points · suggested 90 minutes
Student instructions
- Work independently after agreeing timing and access support with a parent; record any support used.
- All scenario numbers and records are illustrative. Use the stated assumptions and do not invent missing data.
- Use the reference relationships below and a basic calculator when helpful. Show a calculation, retain units, and explain what it means.
- For concept questions, connect a claim with the relevant mechanism or evidence and a specific limit. A supported alternative can satisfy the criteria.
- Keep the answer key and lesson models closed during an independent attempt. Discuss corrections after human marking.
- Use saved investigation plans, observations, revised models, projects, and an oral conference as additional assessment evidence.
Measurement and model relationships
| Relationship | How to use it |
|---|---|
| Length | 10 mm = 1 cm; 100 cm = 1 m |
| Mass and volume | 1,000 g = 1 kg; 1,000 mL = 1 L |
| Mean | Sum comparable values and divide by their count |
| Density | Mass ÷ volume; preserve units such as g/mL or g/cm³ |
| Percentage | Part ÷ stated whole × 100; identify the denominator |
| Change/rate | Ending minus starting value; divide a stated change by its time interval |
| Tidal range | High water minus low water with the same reference |
| Space scale | Actual stated distance ÷ actual km per model cm |
| Energy account | Include relevant stores and transfers; °C is not a joule value |
Coverage and marks
| Chapter | Questions | Points |
|---|---|---|
| Chapter 1 · Inquiry, Measurement & Models | 1, 2, 3, 4, 5 | 15 |
| Chapter 2 · Matter, Mixtures & Water Properties | 6, 7, 8, 9, 10 | 15 |
| Chapter 3 · Energy, Heat & Thermal Design | 11, 12, 13, 14, 15 | 15 |
| Chapter 4 · Electricity, Magnetism & Light | 16, 17, 18, 19, 20 | 15 |
Parent / teacher marking guide
- Each written task has three separate one-point criteria. Award for meaning and reasoning, not keyword matching.
- A different accurate supported answer may receive full credit. Do not require personal or political agreement.
- Keep written marks pending until reviewed by a person. Record the criteria met and one improvement.
- Compare exam evidence with the notebook and project process rather than certify mastery from one total.
Question 1 · 3 points
A towel test reports A gaining 4 g and B 6 g in one trial. Write a supported claim, reasoning, and one limit.
Worked answer
B retains 2 g more under the stated trial if conditions are comparable. Retained water adds wet mass, linking gain with absorption. One trial does not establish every sample or other meanings of best.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: State the bounded 2 g comparison.
- 1 point: Explain water retention and mass gain.
- 1 point: Identify repetition, method, or untested-property limit.
Question 2 · 3 points
A compares dry cotton at 20 seconds with paper at 40 seconds. Name the changed factors and propose a fair material comparison.
Worked answer
Material and timing both differ. Match soaking and draining time, sample dimensions, water source, and measurement while varying material; repeat fresh samples. The current difference cannot isolate material.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Name material and time changes.
- 1 point: Explain the confounding.
- 1 point: Specify matched conditions or fresh repeated trials.
Question 3 · 3 points
A vessel contains 0.6 L and a bag 0.8 kg. Convert each to mL and g and explain why their numbers cannot be added as one measured property.
Worked answer
0.6 L = 600 mL and 0.8 kg = 800 g. Volume and mass are different quantities; 1,400 with no unit would not be a valid total property.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Convert to 600 mL.
- 1 point: Convert to 800 g.
- 1 point: Distinguish unlike quantities and units.
Question 4 · 3 points
A modeled temperature table at 0/5/10 minutes gives 36/32/29 °C. State suitable axes, total drop, and a future-prediction limit.
Worked answer
Use time in minutes horizontally and temperature in °C vertically. The ten-minute drop is 7 °C. The observed pattern does not guarantee indefinite linear cooling or an exact future value without surroundings and a model.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Give labeled time/temperature axes.
- 1 point: Calculate 7 °C drop.
- 1 point: State a supported interval or future-model limit.
Question 5 · 3 points
A model shows a food chain but no population sizes, migration, or seasons. Explain one useful question it can answer and one it cannot, then propose a revision.
Worked answer
It can represent the stated feeding route and arrow direction. It cannot predict an exact future population without further data. Add population and rate/time information or another relevant route to address the wider question, labeling the added evidence.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Name a valid feeding-relationship purpose.
- 1 point: Identify a specific unsupported numerical prediction.
- 1 point: Propose a question-relevant evidence/model revision.
Question 6 · 3 points
A wet cloth dries below boiling in an open room. Explain state change, water destination, and why visible white droplets are different from vapor.
Worked answer
Surface evaporation can occur below boiling. Water enters the air as gas rather than disappear. Water vapor is ordinarily invisible; a visible white cloud consists of tiny droplets or ice, not simply visible gaseous water.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Explain evaporation below boiling.
- 1 point: Account for transferred water.
- 1 point: Distinguish invisible vapor from visible droplets.
Question 7 · 3 points
A uniform modeled material sample is 36 g and 12 cm³, then reshaped without a new substance. Calculate density and explain the physical-change classification and a size limit.
Worked answer
Density is 3 g/cm³. Reshaping changes form while the stated identity remains, so it is physical. A larger matched sample can have the same density if mass and volume grow together; irreversibility alone would not define chemistry.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Calculate 3 g/cm³.
- 1 point: Explain retained identity and shape change.
- 1 point: Give ratio/size or reversibility qualification.
Question 8 · 3 points
A closed model transforms A₂ plus B₂ into two AB particles. Count the atoms and explain why the combinations can change without destroying matter.
Worked answer
Both sides have two A and two B atoms. The new AB combinations represent different particle identity under the stated model, while each atom remains accounted for. A visible sign alone would not provide this full composition account.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Count two A and two B before.
- 1 point: Count the same afterward and identify changed combinations.
- 1 point: Explain conservation rather than atom destruction.
Question 9 · 3 points
A filter removes visible sand from a salt solution. Explain the filter result, the fate of dissolved salt, and an appropriate separation/safety limit.
Worked answer
The filter traps suitable suspended sand, while dissolved salt remains with the water in this model. Evaporation could leave salt residue while water transfers elsewhere, but filtration/clarity alone does not establish pure or drinkable water.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Explain sand separation by filter properties.
- 1 point: Account for dissolved salt.
- 1 point: Name a second method or drinking-safety limit accurately.
Question 10 · 3 points
Using water modeled as 1 g/mL, a 20 g object occupies 50 mL. Calculate its average density and explain why a 20 g compact metal piece could behave differently.
Worked answer
The object averages 0.4 g/mL. A compact piece can have less volume and higher average density despite the same mass; shape/air and displacement affect floating. A small surface-supported item also may require surface-tension reasoning.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Calculate 0.4 g/mL.
- 1 point: Explain equal mass with different volume/density.
- 1 point: Connect geometry/displacement or surface-force limit.
Question 11 · 3 points
A wind-up toy is released and moves, then slows. Describe an initial energy store, motion energy, and where energy can go as it slows.
Worked answer
The wound mechanism stores elastic potential energy; the moving toy has kinetic energy. Slowing redistributes energy into thermal changes, sound, and other pathways including surroundings rather than erase it.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Identify elastic potential energy.
- 1 point: Identify kinetic energy.
- 1 point: Explain later energy pathways rather than destruction.
Question 12 · 3 points
A supplied lighting model receives 200 J, with 50 J visible light and 150 J thermal transfer. Find the light fraction and account for the total, then distinguish usefulness from conservation.
Worked answer
Light fraction is 25%. The outputs sum to 200 J. The thermal output may be less useful for lighting but remains energy and could be useful for a different purpose; no destruction is implied.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Calculate 25%.
- 1 point: Check 200 J total.
- 1 point: Distinguish purpose-dependent usefulness from conserved energy.
Question 13 · 3 points
A 12 °C cup and a 30 °C cup sit in the same 21 °C room. Predict each direction of net heat transfer and explain why 12 °C does not mean 12 J.
Worked answer
The cooler cup receives net energy from surroundings and tends to warm; the warmer cup transfers net energy outward and tends to cool. °C is temperature, not joules; the material/amount model is needed for an energy calculation.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Predict inward transfer to the 12 °C cup.
- 1 point: Predict outward transfer from the 30 °C cup.
- 1 point: Distinguish temperature and energy units/model.
Question 14 · 3 points
Sunlight crosses space, a handle warms through matter, and air circulates around a source. Identify the transfer mechanisms and one combined-pathway limit.
Worked answer
Sunlight transfers energy by radiation, the handle through conduction, and moving air by convection. A real cup or room can use several mechanisms together; insulation does not automatically eliminate every transfer.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Identify radiation and conduction.
- 1 point: Identify convection as bulk fluid movement.
- 1 point: Explain combined mechanisms or insulation limit.
Question 15 · 3 points
Matched mean drops are A 4 °C at 8 tokens and B 6 °C at 4 tokens. Criterion is at most 6 °C and budget at most 5. Recommend and state a needed next check.
Worked answer
B meets both stated conditions. A has a smaller drop but violates cost. Repeat with matched conditions and inspect spread, fit, reuse, or a cheaper A redesign; a new design requires new results.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Apply the performance condition.
- 1 point: Apply budget and select B.
- 1 point: Propose a relevant repeat/tradeoff or redesign check.
Question 16 · 3 points
A neutral model with 8 positive and 8 negative units gains two negative units. Find its net charge and explain whether attraction to neutral paper proves that paper is positive.
Worked answer
It becomes net negative two: 8 positive and 10 negative. Neutral paper can be attracted through a shifted/polarized charge distribution, so attraction alone does not establish opposite net charge.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Find negative two.
- 1 point: Explain transferred negative units rather than created charge.
- 1 point: Explain neutral attraction or insufficient net-charge inference.
Question 17 · 3 points
A single series path has two lamps and an open switch between them. Predict the ideal lamp states and explain why the return wire is still needed when the switch closes.
Worked answer
Both lamps are off because the shared loop is interrupted. Closing it allows a complete return path. Charge is not consumed by the first lamp; energy transfers to the lamps while the circuit still needs the entire conducting route.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Predict both off.
- 1 point: Explain the shared open/closed path.
- 1 point: Distinguish charge circulation from energy transfer.
Question 18 · 3 points
A supplied bar magnet is divided into two smaller bars. What poles does the model assign, and why does a non-attracted shiny washer not prove all metals are nonmagnetic?
Worked answer
Each smaller bar has north and south poles in the ordinary model. Metals differ in response; one washer and method cannot represent every metal, and no detected motion is not necessarily zero field.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Assign both poles to both modeled bars.
- 1 point: Reject one-isolated-pole misconception.
- 1 point: Explain material or detection limit for the washer claim.
Question 19 · 3 points
A plane-mirror ray is 35° from the surface. Find incident and reflected normal angles and explain what a shadow-size change would need to account for.
Worked answer
The incident normal angle is 55° and reflected normal angle also 55°. Shadow size depends on source–object–screen geometry and source extent, so object growth is not the only explanation.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Convert surface angle to 55° normal incidence.
- 1 point: Give reflected normal angle 55°.
- 1 point: Identify a shadow-geometry condition or limit.
Question 20 · 3 points
A modeled blue card reflects only blue. Compare white and green-only light views, and explain why a straight spoon can appear displaced in water.
Worked answer
It can look blue under white light and dark under green-only light because no blue component is supplied. Refraction changes the path from underwater parts so apparent position differs without the spoon breaking. Real material/spectrum responses can exceed this simple model.
Compare each criterion with the learner’s actual reasoning. Accurate supported alternatives may receive full credit. Written answers require human marking.
Marking criteria
- 1 point: Give the two modeled color appearances.
- 1 point: Explain source/reflection relationship.
- 1 point: Explain refraction as apparent rather than physical breakage.