Free notes · Primary 5 and 6
PSLE Science notes
Free PSLE Science notes on one page, for the PSLE Science exam (0009), following MOE's 2023 primary Science syllabus. Full notes for 8 of the 18 syllabus chapters, each with the key idea, the facts and formulas to know, a worked exam question, the common mistakes and exam tips. The other chapters have a checklist of what the syllabus asks for, so the page maps the whole syllabus.
Free to read, print or save as a PDF, with no sign-up. The print layout keeps every chapter and drops the menus. After each chapter, practise on the PSLE Science school papers.
How to use these notes
- Pick one chapter. Read the key idea and the must-know points.
- Close the page and write down what you remember, then check and mark what you missed.
- Try the worked exam question before reading its steps, and read the common mistakes.
- Do questions on that chapter from a school paper and mark them. Redo the wrong ones a few days later.
Syllabus edition
The PSLE Science exam (0009) assesses MOE's 2023 Primary Science syllabus, which covers Primary 3 to 6 in five themes: Diversity, Cycles, Systems, Energy and Interactions. The chapter list below is the syllabus's Standard topics by level. Sources: SEAB, PSLE Science 0009 (examined from 2026), MOE, 2023 Primary Science syllabus (P3 to P6).
Exam format
| Booklet | What it is | Marks |
|---|---|---|
| Booklet A | 30 multiple-choice questions with four options, 2 marks each | 60 |
| Booklet B | 10 to 11 structured questions worth 2, 3, 4 or 5 marks each | 40 |
- One paper of 1 hour 45 minutes. Answer every question in both booklets. 100 marks in all.
The whole syllabus, chapter by chapter
All 18 chapters of the syllabus in order. 8 have full notes on this page. The rest have a checklist of what the syllabus asks you to do.
| Chapter | What it covers | On this page |
|---|---|---|
| 1. Diversity of Living and Non-Living Things (P3) | Characteristics of living things and broad groups. | Checklist |
| 2. Diversity of Materials (P3) | Matching materials to their uses. | Checklist |
| 3. Cycles in Plants and Animals: Life Cycles (P3) | Stages in the life cycles of plants and animals. | Full notes |
| 4. Interaction of Forces: Magnets (P3) | Properties and uses of magnets. | Full notes |
| 5. Plant System: Parts and Functions (P4) | Roots, stem, leaves, flowers and fruits. | Full notes |
| 6. Human System: Digestive System (P4) | The organs of digestion. | Full notes |
| 7. Cycles in Matter and Water: Matter (P4) | Matter and the three states. | Checklist |
| 8. Energy Forms and Uses: Light (P4) | Light, reflection and shadows. | Full notes |
| 9. Energy Forms and Uses: Heat (P4) | Heat, temperature and heat flow. | Full notes |
| 10. Cycles in Plants and Animals: Reproduction (P5) | Reproduction in plants and humans. | Checklist |
| 11. Cycles in Matter and Water: Water (P5) | Changes of state and the water cycle. | Checklist |
| 12. Plant System: Respiratory and Circulatory Systems (P5) | How plants take in air and transport water and food. | Full notes |
| 13. Human System: Respiratory and Circulatory Systems (P5) | Breathing and blood circulation. | Full notes |
| 14. Electrical System (P5) | Circuits, conductors and insulators. | Full notes |
| 15. Energy Forms and Uses: Photosynthesis (P6) | How plants make food using light. | Full notes |
| 16. Energy Conversion (P6) | Forms of energy and how they change. | Full notes |
| 17. Interaction of Forces: Friction, Gravity and Springs (P6) | What forces do and the types of force. | Checklist |
| 18. Interactions within the Environment (P6) | Survival, populations and communities, adaptations and human impact. | Checklist |
PSLE Science at a glance
| Chapter | The one thing to remember |
|---|---|
| Life Cycles of Plants and Animals | Four-stage life cycle: egg, larva, pupa, adult (butterfly, mosquito, beetle) |
| Magnets | Magnetic materials: iron, steel, nickel and cobalt |
| Plant Transport and Photosynthesis | Water + carbon dioxide, with light energy and chlorophyll, gives sugar + oxygen |
| Human Body Systems | Digestion starts in the mouth and is completed in the small intestine |
| Light and Shadows | Light travels in straight lines |
| Heat and Temperature | Heat flows from hotter to colder until both are at the same temperature |
| Electrical Circuits | Closed circuit: the bulb lights. Open circuit: the bulb does not light |
| Energy Forms and Conversion | Energy cannot be created or destroyed, only converted from one form to another |
Notes 1 of 8
Life Cycles of Plants and Animals
Key idea. A life cycle is the series of stages a living thing goes through, from the start of its life to an adult that can reproduce. Butterflies, mosquitoes and beetles have four stages: egg, larva, pupa and adult. Cockroaches, grasshoppers and chickens have three. Flowering plants go from seed to seedling to adult plant, and reproduce through pollination, fertilisation, fruit and seed formation, and seed dispersal.
Must know
- Four-stage life cycle: egg, larva, pupa, adult (butterfly, mosquito, beetle)
- Three-stage life cycle: egg, nymph, adult (cockroach, grasshopper)
- Seeds need water, air and warmth to germinate, but not light
- After fertilisation, the ovary becomes the fruit and the ovules become seeds
What the syllabus asks you to do
- Describe the stages in the life cycles of animals such as the butterfly, mosquito, beetle, cockroach, frog and chicken
- Compare life cycles with three stages and life cycles with four stages
- Describe the life cycle of a flowering plant from seed to adult plant
- Explain pollination and fertilisation and describe how fruits and seeds form
- Describe how seeds are dispersed by wind, water, animals and splitting, and explain why dispersal is important
- State the conditions needed for germination and explain a fair test that investigates them
Life cycles of common animals
| Animal | Stages | Number of stages |
|---|---|---|
| Butterfly | Egg, larva (caterpillar), pupa, adult | 4 |
| Mosquito | Egg, larva, pupa, adult | 4 |
| Beetle | Egg, larva, pupa, adult | 4 |
| Cockroach | Egg, nymph, adult | 3 |
| Grasshopper | Egg, nymph, adult | 3 |
| Chicken | Egg, chick, adult | 3 |
| Frog | Egg, tadpole, young frog, adult | 4 |
Seed
Contains a young plant and seed leaves with stored food
Germination and seedling
Needs water, air and warmth, and the seed leaves feed the young plant
Adult plant
Makes its own food by photosynthesis and produces flowers
Pollination
Pollen grains are transferred from the anther to the stigma
Fertilisation
Male and female cells join in the ovule. The ovary becomes fruit, ovules become seeds
Seed dispersal
Seeds are carried away by wind, water, animals or splitting
Back to the start: Seed
Worked exam question
Mei Ling put 10 green bean seeds on cotton wool in each of three containers. A had dry cotton wool and was placed on a table near a window. B had wet cotton wool and was placed next to A. C had wet cotton wool and was placed in a dark cupboard in the same room. After five days, the seeds in B and C had germinated but those in A had not. (a) Which two set-ups should she compare to find out if water is needed for germination? Explain. (b) What do the results of B and C show? (c) Why did she use 10 seeds in each container instead of one?
- Find the one variable that differs in each pair. A and B differ only in whether there is water. B and C differ only in whether there is light.
- For (a), compare A and B. Everything else is the same (type and number of seeds, cotton wool, light, room), so water is the only variable changed.
- Seeds in B (with water) germinated and seeds in A (without water) did not, so water is needed for germination.
- For (b), compare B and C. Seeds germinated both with light and without light, so light is not needed for germination.
- Give the reason: the young plant uses food stored in the seed leaves, so it does not need light to make food yet.
- For (c), using more seeds makes the results more reliable, because a few seeds might not germinate even when conditions are suitable.
Answer: (a) A and B, because water is the only variable that is different between them. Only the seeds with water germinated, so water is needed. (b) Light is not needed for germination. (c) To make the results more reliable, in case some seeds cannot germinate.
Common mistakes
- Writing 'seeds need sunlight to germinate'.Germination needs water, air and warmth. Light is needed only when the leaves start making food.
- Using pollination and fertilisation as if they mean the same thing.Pollination moves pollen to the stigma. Fertilisation joins male and female reproductive cells inside the ovule, after pollination.
- Writing 'the ovule becomes the fruit'.The ovary becomes the fruit and each fertilised ovule becomes a seed. A fruit with 6 seeds had 6 fertilised ovules.
- Calling a young cockroach a larva.Three-stage life cycles have a nymph. Larva and pupa belong only to four-stage life cycles.
- Saying a mosquito spends its whole life in water.Only the egg, larva and pupa stages are in water. The adult lives on land and flies.
- Giving 'so that the plant can spread' as the reason for dispersal.Add the reason: young plants compete less for space, water, sunlight and mineral salts, so more of them survive.
Exam tips
- In experiment questions, name the one variable that is different between the two set-ups you compare, and say that everything else was kept the same.
- For dispersal questions, give the feature and how it helps, for example 'the wing-like structure allows the fruit to be carried further by the wind'.
- When you are given an unfamiliar life cycle, count the stages and check whether the young look like the adult before you answer.
Notes 2 of 8
Magnets
Key idea. A magnet attracts magnetic materials, which are iron, steel, nickel and cobalt. Every magnet has a north pole and a south pole, where its force is strongest. Like poles repel and unlike poles attract, so only repulsion proves that an object is a magnet. Magnets can be made by stroking a magnetic material in one direction, or by passing electricity through a coil of wire around an iron nail.
Must know
- Magnetic materials: iron, steel, nickel and cobalt
- Like poles repel, unlike poles attract
- Only repulsion proves that an object is a magnet
- More coils or more batteries in series make an electromagnet stronger
What the syllabus asks you to do
- State the properties of magnets: they attract magnetic materials, have two poles and point north to south when hung freely
- Classify materials as magnetic or non-magnetic
- Explain that like poles repel and unlike poles attract, and use repulsion to identify a magnet
- Describe how to make a magnet by the stroke method and by the electrical method
- Explain how the number of coils and the number of batteries affect the strength of an electromagnet
- Describe uses of magnets and electromagnets in daily life
Testing an unknown bar with a known magnet
| What you observe | Conclusion |
|---|---|
| One end of the bar is repelled by a pole of the magnet | The bar is a magnet |
| Both ends are attracted to both poles and are never repelled | The bar is a magnetic material but not a magnet |
| Neither end is attracted | The bar is made of a non-magnetic material |
A line graph of paper clips picked up against number of coils, from 0 to 40 coils. The results rise in a straight line: 3 clips at 10 coils, 6 at 20 and 9 at 30. A dashed line continues the pattern to a predicted 12 clips at 40 coils.
Worked exam question
Ravi had three bars, X, Y and Z, that look the same. He recorded these results. End 1 of X and end 1 of Y pushed each other away. End 2 of X and end 1 of Y pulled towards each other. Both ends of Z were attracted to both ends of X. (a) Which bars are magnets? Explain. (b) Is Z a magnet? Explain. (c) Which of these could Z be made of: iron, copper or plastic?
- Look for repulsion first, because only repulsion proves that a bar is a magnet.
- End 1 of X and end 1 of Y repelled. Repulsion only happens between like poles of two magnets, so X and Y are both magnets.
- The second result fits: end 2 of X is the opposite pole to end 1 of X, so it is unlike end 1 of Y, and unlike poles attract.
- Z was attracted to both ends of magnet X and was never repelled. If Z were a magnet, one of its ends would have been repelled by one of the poles of X.
- So Z is a magnetic material but not a magnet. Copper and plastic are non-magnetic and would not be attracted at all, so Z must be iron.
Answer: (a) X and Y are magnets, because end 1 of X and end 1 of Y repelled. (b) Z is not a magnet: both its ends were attracted to both poles of X and none was repelled, so it is a magnetic material. (c) Iron.
Common mistakes
- Writing 'magnets attract all metals'.Only iron, steel, nickel and cobalt are magnetic. Copper, aluminium, brass, gold and silver are not.
- Saying a bar is a magnet because it was attracted to a magnet.Look for repulsion. Only repulsion proves an object is a magnet, because magnetic materials are attracted too.
- Stroking a steel bar back and forth with a magnet.Stroke in one direction only, with the same pole, lifting the magnet well away after each stroke.
- Saying a bar magnet is strongest in the middle.The force is strongest at the poles, which is why paper clips cluster at the ends.
- Saying magnetic force cannot pass through paper or water.Magnetic force acts through non-magnetic materials such as paper, glass, plastic and water.
Exam tips
- For 'which bars are magnets' questions, look for the word 'repel' or 'pushed away' in the data first. Without repulsion you cannot conclude that an object is a magnet.
- In electromagnet experiments, name the variable changed (number of coils or number of batteries), the variables kept the same (the same nail, the same battery), and how strength was measured (the number of paper clips attracted).
- Use the words 'magnetic' and 'non-magnetic' to describe materials, not 'metal' and 'not metal'.
Notes 3 of 8
Plant Transport and Photosynthesis
Key idea. Plants make their own food by photosynthesis: chlorophyll traps light energy, which is used to make sugar from water and carbon dioxide, and oxygen is given out. Water and mineral salts travel up from the roots in the water-carrying tubes. Food made in the leaves travels to all parts of the plant in the food-carrying tubes, which lie in the outer layer of a woody stem.
Must know
- Water + carbon dioxide, with light energy and chlorophyll, gives sugar + oxygen
- Water-carrying tubes carry water and mineral salts up from the roots
- Food-carrying tubes carry food from the leaves to all parts, up and down
- Iodine turns blue-black when starch is present
What the syllabus asks you to do
- State the functions of the roots, stem and leaves of a plant
- Describe how water and mineral salts travel from the roots to the leaves in the water-carrying tubes
- Describe how food made in the leaves travels to other parts of the plant in the food-carrying tubes
- State what a plant needs for photosynthesis and what it produces
- Explain experiments on photosynthesis, such as covering part of a leaf and counting bubbles from a water plant
- Explain the results of ring-barking and coloured-water experiments
Water-carrying tubes and food-carrying tubes compared
| Feature | Water-carrying tubes | Food-carrying tubes |
|---|---|---|
| What they carry | Water and mineral salts | Food (sugar) made in the leaves |
| Direction | From the roots upwards to the leaves and other parts | From the leaves to all parts, up and down |
| Position in a woody stem | Further inside the stem | In the outer layer, just under the bark |
| Removed when a ring of bark is cut away? | No | Yes |
Soil
Contains water with dissolved mineral salts
Root hairs
Take in water and mineral salts from the soil
Water-carrying tubes
Carry the water up through the root and stem
Leaves
Water is used with carbon dioxide to make food in photosynthesis
Stomata
Some water escapes into the air as water vapour
Worked exam question
Ahmad removed a ring of bark, including the outer layer of the stem, from the main stem of a plant. After a few weeks, the part of the stem just above the ring had become swollen, and the leaves stayed green and did not wilt. (a) Explain why the stem just above the ring became swollen. (b) Explain why the leaves did not wilt. (c) Predict what would happen to the plant after a long time, and explain.
- Identify what was removed: the food-carrying tubes are in the outer layer of the stem, so removing the ring cut them. The water-carrying tubes are further inside, so they were not removed.
- For (a), food made in the leaves travels down the stem in the food-carrying tubes. At the ring, the tubes are missing, so the food cannot pass. It collects just above the ring and the stem swells.
- For (b), the water-carrying tubes are still whole, so water from the roots still reaches the leaves. The leaves get enough water, so they do not wilt.
- For (c), the roots are below the ring, so food from the leaves can no longer reach them. Without food, the root cells cannot get energy to stay alive.
- Link to the whole plant: when the roots die, they can no longer take in water, so the whole plant will die.
Answer: (a) The food-carrying tubes were removed, so food from the leaves could not travel down past the ring and collected above it. (b) The water-carrying tubes were not removed, so water still reached the leaves. (c) The roots would die because no food reaches them, and then the plant would die because water can no longer be taken in.
Common mistakes
- Writing 'plants take in food from the soil through their roots'.Plants make their own food by photosynthesis. Roots take in only water and mineral salts.
- Saying the water-carrying tubes take food to the roots.Water-carrying tubes move water and mineral salts up. Food-carrying tubes move food from the leaves to all parts.
- Saying plants give out only oxygen, never carbon dioxide.Plants respire day and night, giving out carbon dioxide. In light, photosynthesis is faster, so more oxygen is given out overall.
- Writing that chlorophyll makes the food by itself.Chlorophyll traps light energy. The plant also needs water and carbon dioxide to make sugar.
- Moving a lamp closer in a bubble experiment without checking the water temperature.Remember the lamp also heats the water, so keep the water temperature the same for a fair test.
Exam tips
- Use the exact terms 'water-carrying tubes' and 'food-carrying tubes', and say which way each substance travels.
- When you explain an experiment, state what was changed, what happened, and link it to photosynthesis, for example 'brighter light, so the plant photosynthesised faster and gave off more oxygen'.
- For ring-barking questions, say what happens above the ring, below the ring and to the leaves, each with its reason.
Notes 4 of 8
Human Body Systems
Key idea. A system is a group of organs working together. The digestive system breaks food down and absorbs it in the small intestine. The respiratory system takes oxygen into the blood in the lungs and removes carbon dioxide. The circulatory system, made of the heart, blood vessels and blood, carries these substances around the body. During exercise, breathing rate and heart rate rise so muscles get more oxygen and digested food.
Must know
- Digestion starts in the mouth and is completed in the small intestine
- Digested food is absorbed in the small intestine, water in the large intestine
- Heart rate per minute = beats counted in 15 seconds × 4
- During exercise, breathing rate and heart rate both increase
What the syllabus asks you to do
- State the functions of the skeletal and muscular systems
- Identify the organs of the digestive system and describe what happens to food in each
- Describe how the respiratory system takes in oxygen and removes carbon dioxide
- Describe how the circulatory system transports oxygen, digested food and carbon dioxide
- Explain how the systems work together, for example during exercise
- Calculate and interpret heart rate and breathing rate data
Human body systems and their jobs
| System | Main parts | Main job |
|---|---|---|
| Digestive | Mouth, gullet, stomach, small intestine, large intestine | Breaks down food and absorbs digested food into the blood |
| Respiratory | Nose, windpipe, lungs | Takes in oxygen and removes carbon dioxide |
| Circulatory | Heart, blood vessels, blood | Carries oxygen, digested food and carbon dioxide around the body |
| Skeletal | Bones | Supports the body, gives it shape, protects organs and allows movement |
| Muscular | Muscles | Contract and pull on bones to move them |
A line graph of heart rate against time from 0 to 14 minutes. Heart rate is 75 beats per minute at rest, rises to 120 during the run from minute 2 to minute 7, then falls gradually back to 75 by minute 14 as he rests.
Worked exam question
Jun Wei measured his heart rate and breathing rate at rest and again after running for 5 minutes. At rest: heart rate 75 beats per minute, breathing rate 16 breaths per minute. After running: heart rate 120 beats per minute, breathing rate 30 breaths per minute. (a) By how much did his heart rate increase? (b) Explain why his breathing rate and heart rate both increased. (c) Name another system that supplies what his muscles need, and state what it supplies.
- For (a), subtract: 120 − 75 = 45 beats per minute.
- For (b), start with the muscles: when running, his leg muscles work harder and need more energy.
- To release more energy, the muscles need more oxygen and digested food, and they produce more carbon dioxide.
- Breathing rate increased so that more oxygen could be taken into the lungs and more carbon dioxide removed from the body.
- Heart rate increased so that blood transported oxygen and digested food to the muscles, and carbon dioxide away from them, faster.
- For (c), the digestive system supplies the digested food that is absorbed into the blood in the small intestine.
Answer: (a) 45 beats per minute. (b) His muscles needed more energy, so they needed more oxygen and digested food and produced more carbon dioxide. He breathed faster to take in more oxygen and remove more carbon dioxide, and his heart beat faster to transport these substances to and from the muscles more quickly. (c) The digestive system, which supplies digested food.
Common mistakes
- Writing 'digestion happens in the stomach' as the whole answer.Name all three places: digestion starts in the mouth, continues in the stomach and is completed in the small intestine.
- Saying digested food is absorbed in the large intestine.Digested food is absorbed in the small intestine. The large intestine absorbs water.
- Writing 'we breathe in oxygen and breathe out carbon dioxide'.We breathe in air. The air we breathe out has less oxygen and more carbon dioxide.
- Saying the heart makes or cleans blood.The heart pumps blood around the body through the blood vessels.
- Explaining a faster heart rate with 'the body needs more oxygen' only.Say the muscles need more energy, so the heart pumps faster to carry more oxygen and digested food to them.
Exam tips
- When asked how two systems work together, name both systems and say what each one does in that situation.
- In heart rate questions, show how you change the count to one minute, and give the unit, beats per minute.
- Use the phrases 'absorbed into the bloodstream in the small intestine' and 'oxygen passes into the blood in the lungs'. They match what markers look for.
Notes 5 of 8
Light and Shadows
Key idea. We see an object when light from it enters our eyes, either straight from a light source or reflected off the object. Light travels in straight lines, so an opaque or translucent object blocks it and casts a shadow on the side away from the light. Moving the object closer to the light source makes the shadow larger, and moving it closer to the screen makes it smaller.
Must know
- Light travels in straight lines
- Transparent lets most light through, translucent lets some through, opaque lets none through
- An object closer to the light source casts a larger shadow
- Shadows are shortest around midday and always point away from the Sun
What the syllabus asks you to do
- Explain that we see an object when light from it enters our eyes
- Distinguish between sources of light and objects that only reflect light
- Describe how light travels in straight lines and is reflected by surfaces
- Classify materials as transparent, translucent or opaque
- Explain how shadows are formed
- Predict how the size and shape of a shadow change with the positions of the light source, object and screen
Transparent, translucent and opaque materials
| Type | How much light passes through | Examples |
|---|---|---|
| Transparent | Most light, so objects behind are seen clearly | Clear glass, clear plastic |
| Translucent | Some light, so objects behind look blurred and the shadow is lighter | Frosted glass, tracing paper |
| Opaque | No light, so it casts a dark shadow | Wood, metal, cardboard |
A line graph of shadow height against the card's distance from the torch. The results are 24 cm at 10 cm, 12 cm at 20 cm and 8 cm at 30 cm. A dashed line continues to a predicted 6 cm at 40 cm. The shadow gets shorter as the card moves away from the torch.
Worked exam question
Amy placed a torch 60 cm from a screen. She held a card 4 cm tall between them, moved it to different distances from the torch and measured the height of its shadow. At 10 cm from the torch the shadow was 24 cm tall, at 20 cm it was 12 cm tall and at 30 cm it was 8 cm tall. (a) Describe the relationship between the distance of the card from the torch and the height of the shadow. (b) Explain this relationship. (c) Predict the height of the shadow when the card is 40 cm from the torch.
- For (a), read the trend: as the distance from the torch increased from 10 cm to 30 cm, the shadow height decreased from 24 cm to 8 cm.
- For (b), use how light travels: light from the torch travels in straight lines and spreads out. When the card is near the torch, it blocks a wider part of the spreading light, so the shadow on the screen is larger.
- For (c), look for a pattern in the numbers: 10 × 24 = 240, 20 × 12 = 240 and 30 × 8 = 240, so distance × shadow height is always 240.
- At 40 cm: 240 ÷ 40 = 6, so the shadow should be 6 cm tall.
- Check that it fits the trend: 6 cm is smaller than 8 cm, as expected when the card moves further from the torch.
Answer: (a) The further the card is from the torch, the shorter its shadow. (b) The card blocks more of the spreading light when it is closer to the torch. (c) 6 cm.
Common mistakes
- Listing the Moon as a source of light.The Moon only reflects light from the Sun. A source of light must give off its own light.
- Drawing arrows from the eye to the object.Draw light from the source to the object, then from the object into the eye, with arrows pointing towards the eye.
- Describing a shadow as a dark copy of the object, with its colours.A shadow is an area where light is blocked, so it shows only the outline of the object.
- Saying tracing paper casts no shadow.Translucent materials block some of the light, so they cast a lighter shadow.
- Saying an object moved closer to the torch casts a smaller shadow.Closer to the light source, the object blocks more of the spreading light, so its shadow is larger.
- Saying shadows are shortest in the evening.Shadows are shortest around midday, when the Sun is highest, and longest when the Sun is low.
Exam tips
- In 'how do we see' answers, describe the whole path: light from the source falls on the object, is reflected by the object and enters the eyes.
- For shadow size questions, say which distance changed and which stayed the same before you give the effect.
- Look for a number pattern in shadow tables, such as distance × height staying the same, before you make a prediction.
Notes 6 of 8
Heat and Temperature
Key idea. Heat is a form of energy, while temperature measures how hot or cold something is, in degrees Celsius. Heat always flows from a hotter object to a colder one until both reach the same temperature. Objects that gain heat usually expand, and objects that lose heat contract. Metals are good conductors of heat, while plastic, wood, styrofoam and air are poor conductors that slow heat flow.
Must know
- Heat flows from hotter to colder until both are at the same temperature
- Gain heat and expand, lose heat and contract
- Ice melts at 0 °C, pure water boils at 100 °C, body temperature is about 37 °C
- Metals are good conductors of heat, trapped air is a very poor conductor
What the syllabus asks you to do
- Distinguish between heat and temperature, and measure temperature with a thermometer in degrees Celsius
- Explain that heat flows from a hotter place or object to a colder one until both are at the same temperature
- Describe the effects of heat gain and heat loss, including expansion, contraction and changes of state
- Classify materials as good or poor conductors of heat and relate this to their uses
- Explain the results of fair tests on how well materials conduct heat
Good and poor conductors of heat in daily life
| Material | Conductor of heat | Everyday use |
|---|---|---|
| Copper, aluminium, steel | Good | Cooking pots and kettles, so food heats quickly |
| Plastic, wood | Poor | Pot and kettle handles that stay cool enough to hold |
| Styrofoam | Poor, because of trapped air | Boxes that keep ice cream cold or food warm |
| Cloth, wool | Poor | Oven gloves and warm clothing |
A line graph of water temperature against time from 0 to 10 minutes. Both cups start at 80 °C. The metal cup cools quickly to 50 °C, while the plastic cup cools slowly to 65 °C. A dashed line at 30 °C shows room temperature, which both cups of water would eventually reach.
Worked exam question
Jia Hui poured 200 ml of water at 80 °C into a metal cup and 200 ml of water at 80 °C into a plastic cup of the same size and shape. After 10 minutes, the water in the metal cup was at 50 °C and the water in the plastic cup was at 65 °C. The room temperature was 30 °C. (a) Calculate the drop in temperature in each cup. (b) Explain the difference. (c) Predict the temperature of the water in both cups after a few hours, and explain.
- For (a), subtract the final temperature from the starting temperature. Metal cup: 80 − 50 = 30 °C. Plastic cup: 80 − 65 = 15 °C.
- For (b), first say which way heat flows: the water is hotter than the surrounding air, so it loses heat to the surroundings through the cup.
- Metal is a good conductor of heat, so heat flowed through the metal cup quickly and the water lost heat faster.
- Plastic is a poor conductor of heat, so heat flowed through the plastic cup slowly and the water lost heat more slowly.
- For (c), heat keeps flowing from the water to the cooler air until they are at the same temperature, so both cups of water will end up at room temperature.
Answer: (a) The metal cup dropped 30 °C and the plastic cup dropped 15 °C. (b) Metal is a better conductor of heat than plastic, so the water in the metal cup lost heat to the surroundings faster. (c) Both will be at 30 °C, room temperature, because heat flows from the water to the air until they are at the same temperature.
Common mistakes
- Writing 'the cold from the ice flows into my hand'.Only heat flows. Write that heat flows from the hand into the ice, so the hand loses heat.
- Using heat and temperature as if they mean the same thing.Heat is a form of energy. Temperature, measured in °C, tells you how hot or cold something is.
- Saying a styrofoam box 'keeps the cold in'.Styrofoam is a poor conductor of heat, so it slows down heat flowing in from the warmer surroundings.
- Saying a metal spoon in a room is colder than a wooden spoon in the same room.Both are at room temperature. Metal feels colder because it conducts heat away from your hand faster.
- Saying boiling water keeps getting hotter while it stays on the stove.Boiling water stays at 100 °C while it gains heat and changes into water vapour.
Exam tips
- Use 'gains heat' and 'loses heat', and say where the heat flows from and to, such as 'heat flows from the hot water to the cooler air'.
- For conductor experiments, name what was changed (the material) and what was kept the same (the volume of water, the starting temperature, the size and shape of the container and the time).
- In expansion questions, say which material gains heat and expands, then link that to what you can see happening.
Notes 7 of 8
Electrical Circuits
Key idea. A bulb lights up only when it is part of a closed circuit, an unbroken path from one end of the batteries to the other. Conductors such as metals let electricity through, while insulators such as plastic do not. More batteries in series make bulbs brighter, more bulbs in series make them dimmer, and bulbs in parallel stay lit even if another bulb fuses.
Must know
- Closed circuit: the bulb lights. Open circuit: the bulb does not light
- More batteries in series give brighter bulbs, while batteries in parallel last longer
- Bulbs in series share one path, so one fused bulb puts them all out
- Bulbs in parallel each have their own path, so the others stay lit
What the syllabus asks you to do
- Identify the parts of an electric circuit and read simple circuit diagrams
- Explain that a bulb lights up only when it is part of a closed circuit
- Classify materials as electrical conductors or electrical insulators
- Predict how the number and arrangement of batteries and bulbs affect the brightness of bulbs
- Compare bulbs in series and in parallel, including what happens when one bulb fuses
- Describe how to use electricity safely
Series and parallel arrangements compared (all bulbs and batteries identical)
| Arrangement | Brightness | If one bulb fuses |
|---|---|---|
| One bulb, one battery | Normal brightness | The bulb goes out |
| Two bulbs in series, one battery | Each bulb is dimmer | All the bulbs go out |
| Two bulbs in parallel, one battery | Each bulb is about as bright as one bulb alone | The other bulb stays lit |
| One bulb, two batteries in series | Brighter | The bulb goes out |
| One bulb, two batteries in parallel | About as bright as with one battery, but lasts longer | The bulb goes out |
Start at the batteries
Put your finger on one end of the batteries
Follow the path
Trace the wire through the bulb you are checking
Check every switch
Every switch on this path must be closed
Check every bulb
No bulb on this path may be fused
Reach the other end
An unbroken path back to the batteries means the bulb lights up
Worked exam question
Two batteries are connected in series. Bulbs P and Q are connected in parallel to the batteries. Switch S1 is on the branch with bulb P only. Switch S2 is next to the batteries, on the main path that all the electricity must pass through. (a) Which bulb lights up when S1 is open and S2 is closed? (b) Both switches are closed and bulb P fuses. What happens to bulb Q? Explain. (c) Both switches are closed and both bulbs work. A third battery is added in series. What happens to the brightness of P and Q?
- Trace the paths first. Every path passes through S2. Only the path through P also passes through S1. The path through Q does not pass through S1.
- For (a), S2 is closed, so the main path is complete. S1 is open, so P's branch has a gap. Q's branch forms a closed circuit, so only Q lights up.
- For (b), the fused filament breaks only P's branch. Q is on a separate branch that still forms a closed circuit with the batteries.
- So Q stays lit, and it stays about as bright as before, because each branch in parallel works on its own.
- For (c), more batteries in series give a greater electric current through each branch, so both bulbs become brighter.
Answer: (a) Only Q lights up. (b) Q stays lit, because it is on a separate branch that still forms a closed circuit. (c) Both P and Q become brighter.
Common mistakes
- Saying a bulb lights up because it is touching the battery.Trace an unbroken path from one end of the battery, through the bulb, and back to the other end.
- Saying three bulbs in parallel are each dimmer than one bulb alone.Bulbs in parallel each stay about as bright as one bulb alone. Only bulbs in series get dimmer.
- Adding a battery in parallel to make a bulb brighter.Batteries in series make bulbs brighter. Batteries in parallel give the same brightness but last longer.
- Assuming a switch next to one bulb controls every bulb.A switch controls only the bulbs whose path passes through it, so trace each bulb's path separately.
- Calling tap water an electrical insulator.Tap water conducts electricity, so switches and plugs must never be touched with wet hands.
Exam tips
- Trace each path with your finger from one end of the batteries back to the other. A bulb lights up only if its path is complete.
- Use the words 'closed circuit' and 'open circuit' in explanations, not just 'connected' or 'not connected'.
- For brightness questions, count the batteries in series and the bulbs in series first, and treat each parallel branch on its own.
Notes 8 of 8
Energy Forms and Conversion
Key idea. Energy is needed to do work and exists in forms such as kinetic, gravitational potential, elastic potential, chemical potential, electrical, light, heat and sound energy. Energy cannot be created or destroyed, only converted from one form to another, and some is usually converted into heat and sound. The Sun is the main source of energy on Earth, and plants convert its light energy into chemical potential energy in food.
Must know
- Energy cannot be created or destroyed, only converted from one form to another
- A higher object has more gravitational potential energy, a faster object more kinetic energy
- Food, fuels and batteries store chemical potential energy
- Friction converts kinetic energy into heat and sound energy
What the syllabus asks you to do
- Recognise that energy is needed to do work and that the Sun is the main source of energy on Earth
- Identify kinetic, gravitational potential, elastic potential, chemical potential, electrical, light, heat and sound energy
- Describe the energy conversions in everyday objects and activities
- Explain that energy cannot be created or destroyed, only converted from one form to another
- Explain how plants convert light energy into chemical potential energy and how animals get energy from food
- Explain experiments on how the height of release or the amount of stretching affects how far an object moves
Forms of energy
| Form of energy | What it is | Example |
|---|---|---|
| Kinetic | Energy of a moving object | A rolling ball |
| Gravitational potential | Stored because of height above the ground | A book on a high shelf |
| Elastic potential | Stored in a stretched or squeezed object | A stretched rubber band |
| Chemical potential | Stored in food, fuels and batteries | Rice, petrol, a torch battery |
| Electrical | Carried by electricity | Electricity flowing in a circuit |
| Light, heat and sound | Given out by lamps, fires and vibrating objects | A lit bulb, a campfire, a guitar string |
The Sun
Gives out light energy
Rice plant
Photosynthesis converts light energy into chemical potential energy in food
Boy eats rice
The chemical potential energy is now stored in his body
Boy runs
Chemical potential energy is converted into kinetic energy and heat energy
Worked exam question
Wei Ling released a toy car from different heights on a ramp and measured how far it travelled along the floor. From 10 cm it travelled 40 cm, and from 30 cm it travelled 120 cm. From 20 cm, three trials gave 78 cm, 80 cm and 82 cm. (a) Calculate the average distance for the 20 cm height. (b) Describe the relationship between the height of release and the distance travelled, and explain it using energy. (c) Predict the distance for a height of 25 cm. (d) Why does the car stop in the end?
- For (a), add the trials and divide by the number of trials: (78 + 80 + 82) ÷ 3 = 240 ÷ 3 = 80 cm.
- For (b), read the trend: the higher the release point, the further the car travels (10 cm gives 40 cm, 20 cm gives 80 cm, 30 cm gives 120 cm).
- Explain with energy: at a greater height the car has more gravitational potential energy. More of it is converted into kinetic energy, so the car moves faster and travels further.
- For (c), spot the pattern: each distance is 4 times the height (4 × 10 = 40, 4 × 20 = 80, 4 × 30 = 120), so for 25 cm, 4 × 25 = 100 cm.
- For (d), friction between the wheels and the floor converts the car's kinetic energy into heat and sound energy until it has no kinetic energy left.
Answer: (a) 80 cm. (b) The higher the release point, the further the car travels, because it has more gravitational potential energy, which is converted into more kinetic energy. (c) 100 cm. (d) Friction converts its kinetic energy into heat and sound energy, so it slows down and stops.
Common mistakes
- Writing 'the energy is used up' when a toy car stops.Write that the energy is converted into other forms, often heat and sound that are not useful.
- Calling the energy stored in a battery 'electrical energy'.A battery stores chemical potential energy and converts it into electrical energy when the circuit is closed.
- Saying a ball has the most kinetic energy at the top of its bounce.At the top it stops for a moment, so its energy is mainly gravitational potential energy. Kinetic energy is greatest just before landing.
- Starting a food energy chain at the plant instead of the Sun.Start with light energy from the Sun, which plants convert into chemical potential energy.
- Writing only 'chemical potential energy to light energy' for a torch.Show every step: chemical potential energy to electrical energy, then to light and heat energy.
Exam tips
- Write energy conversions as a chain using 'is converted into', and name every form, including the heat and sound that are not useful.
- When a moving object slows down or stops, mention friction or air resistance converting kinetic energy into heat (and sound) energy.
- In ramp and catapult experiments, link the variable you changed to the energy stored at the start, then to kinetic energy, then to the distance travelled.
Syllabus checklist for the rest
What the syllabus asks you to do in the chapters, and parts of chapters, that do not have full notes yet. Each point is the syllabus learning outcome in plain words. Tick each one you can do without looking.
Chapter 1. Diversity of Living and Non-Living Things (P3)
2 points to check
- Describe living things as needing water, food and air, and as growing, responding and reproducing.
- Recognise broad groups: flowering and non-flowering plants, animals (amphibians, birds, fish, insects, mammals, reptiles), fungi and bacteria, and classify by similarities and differences.
Chapter 2. Diversity of Materials (P3)
1 point to check
- Relate the uses of wood, metal, ceramic, rubber, glass, plastic and fabric to their strength, flexibility, ability to float or sink, waterproofness and transparency.
Chapter 7. Cycles in Matter and Water: Matter (P4)
1 point to check
- State that matter has mass and occupies space, and compare solids, liquids and gases by shape and volume.
Chapter 10. Cycles in Plants and Animals: Reproduction (P5)
3 points to check
- Recognise the cell as the basic unit of life, and that reproduction passes characteristics from parents to offspring.
- Describe sexual reproduction in flowering plants: pollination, fertilisation, seed dispersal and germination.
- Recognise fertilisation in humans, when a sperm fuses with an egg, and its similarity to fertilisation in flowering plants.
Chapter 11. Cycles in Matter and Water: Water (P5)
2 points to check
- Describe melting, freezing, boiling, evaporation and condensation, and the melting point of ice and boiling point of water.
- Explain the roles of evaporation and condensation in the water cycle, why the water cycle matters, and the impact of water pollution.
Chapter 17. Interaction of Forces: Friction, Gravity and Springs (P6)
2 points to check
- Identify a force as a push or a pull, and show that a force can move, speed up, slow down, stop or turn an object, or change its shape.
- Give examples of magnetic, gravitational, elastic spring and frictional forces.
Chapter 18. Interactions within the Environment (P6)
4 points to check
- Identify factors that affect survival: temperature, light, water, food and other organisms (producers, consumers, decomposers), and what happens when an environment becomes unfavourable.
- Tell an organism, a population and a community apart, and show that different habitats support different communities.
- Show that structural and behavioural adaptations help organisms cope, feed, escape predators and reproduce.
- Give examples of positive and negative human impact on the environment.
If your child is struggling
- Find the exact chapter and point. The checklists and common mistakes on this page show where an answer breaks down.
- Go back to that chapter's worked question and do it again without the steps.
- Ask the school teacher which chapters the class has covered and which are tested next.
- If several chapters are weak, work on one at a time, with short timed questions, rather than rereading everything.