Year 3 Science — Complete Revision (UASA)

🌿 Year 3 Science — Complete Revision Notes (UASA)

A complete, text-only study guide for a 9-year-old. Read slowly, practise the experiments, and try the quiz at the end. Keep calm — you can do it!

References and where to learn more (optional)

If you want official curriculum info or extra reading, these websites often have helpful pages for teachers and students:

Ministry of Education Malaysia (MOE) — https://www.moe.gov.my
Malaysia Digital Textbooks (Textbook division) — https://textbook.moe.gov.my
BBC Bitesize (child-friendly science explanations) — https://www.bbc.co.uk/bitesize
ScienceKids (experiments and facts for children) — https://www.sciencekids.co.nz

Use these only if you have internet access — the notes below are complete without visiting other sites.

How to use this page

Read one topic at a time. Try to explain each point out loud as if you are teaching someone.
Do the simple experiments with an adult present — they are safe and help you remember better.
Use the examples: change the items to things in your home so learning feels familiar.
After reading all topics, try the 30 MCQs. Check the answers only after you finish.

1. HUMANS

Humans are living things that grow, move, breathe, eat, feel and reproduce. Our body is made of many parts and systems that work together.

Main body systems — simple explanation

Respiratory system: Helps us breathe. Air enters through the nose or mouth, goes down the windpipe and into the lungs. The lungs take in oxygen which the body needs, and remove carbon dioxide.
Digestive system: Changes the food we eat into small usable parts called nutrients. Food goes in the mouth, down to the stomach and then to the intestines where the body takes the nutrients.
Circulatory system: Includes the heart and blood vessels. The heart pumps blood to carry oxygen and nutrients to every part of the body.
Skeletal system: All the bones in your body. Bones give shape and protect important organs like the brain (protected by the skull).
Muscular system: Muscles pull on bones to move the body (you need muscles to run, jump, smile).
Nervous system: The brain and nerves. The brain controls actions and sends messages to the body (for example, your hand moves away if you touch something hot).

The five senses — what they do

Eyes (sight): See colours, shapes and movement. Example: noticing a red stop sign.
Ears (hearing): Hear sounds, loud or soft. Example: hearing a bell.
Nose (smell): Smell food, flowers, or smoke.
Tongue (taste): Tastes sweet, sour, salty and bitter.
Skin (touch): Feels hot, cold, rough or smooth.

Example activity: Ask a parent to blindfold you. Smell three different things (apple, soap, lemon) and guess what they are using only your nose. This helps you practice the sense of smell.

Short facts & tips

When you run, you breathe faster because your muscles need more oxygen.
Healthy food and exercise keep the heart and muscles strong.
Teeth help break food into smaller pieces before digestion starts.

2. ANIMALS

Animals are living things that need food, air, water and shelter to survive. They move, grow and make young. Animals can be grouped by their features.

Main groups and what makes each group special

Mammals: Have hair or fur, usually give birth to live young and feed milk to their babies. Examples: humans, cats, cows.
Birds: Have feathers and beaks; most have wings and lay eggs. Examples: chicken, pigeon.
Fish: Live in water, breathe with gills and have fins. Examples: goldfish, catfish.
Amphibians: Live in water and on land at different life stages; many start life with gills, then develop lungs (e.g., frogs).
Reptiles: Have dry scaly skin and lay eggs on land. Examples: lizards, turtles.
Insects: Small animals with six legs and often wings. Examples: ants, butterflies.

Food chains and how energy moves

A food chain shows who eats whom. Plants make food from sunlight. A herbivore eats plants, a carnivore eats other animals.

Example food chain: Grass → Grasshopper → Frog → Snake → Eagle

Example activity: Draw a simple food chain from things in your home or school (e.g., garden plant → caterpillar → bird). Label who is the producer and who are the consumers.

Adaptation — how animals survive

Camels can survive with less water because their bodies store fat in humps and reduce water loss.
Fish have gills to extract oxygen from water.
Birds have hollow bones and feathers to help them fly.

3. PLANTS

Plants are living things. They cannot move from place to place, but they grow and make food themselves using sunlight. This process is called photosynthesis.

Parts of a plant and what each part does

Root: Holds the plant in the ground and soaks up water and nutrients from the soil.
Stem: Keeps the plant upright and moves water and nutrients between roots and leaves.
Leaf: Makes food using sunlight, water and carbon dioxide from the air.
Flower: Helps the plant make seeds by attracting insects for pollination.
Fruit: Protects seeds and sometimes helps seeds spread when animals eat the fruit.
Seed: Contains the young plant that can grow into a new plant.

Photosynthesis — in simple words

Leaves use sunlight + water + air to make food (a kind of sugar) that the plant uses to grow. Plants also give out oxygen — people and animals need oxygen to breathe.

Example activity (easy): Place a small plant in a shaded area for 3–4 days and one in sunlight. Watch how the plant in sunlight stays greener and healthier because it gets light for photosynthesis.

Plant needs and care

Most plants need sunlight, water, air and good soil to grow.
Too much water can cause root rot; too little water makes the plant wilt.
Different plants like different amounts of sunlight: some like direct sun, others prefer shade.

4. MEASUREMENT

Measurement helps us know how long, heavy, hot or long something lasts. Using correct units is important.

Common measurement types and tools

Length: Metre (m), centimetre (cm) — use a ruler or tape. Example: A pencil may be 15 cm long.
Mass (weight): Kilogram (kg), gram (g) — use a scale. Example: A small apple might be 150 g.
Time: Seconds, minutes, hours — use a clock. Example: One lesson might be 30 minutes.
Temperature: Degrees Celsius (°C) — use a thermometer. Example: Room temperature is about 25°C.

Example activity: Measure the length of different things at home (pencil, book, table) and write down the numbers in cm. Practice converting: 100 cm = 1 m.

Useful tips

Always start measuring from zero on the ruler, not from the edge of the ruler if it is damaged.
For mass, use small scales for light things and big scales for heavy things.

5. DENSITY — WHY THINGS FLOAT OR SINK

Density tells us whether something is heavy for its size. If it is lighter than water, it floats; if heavier, it sinks.

How to think about density

Imagine two boxes the same size. One is filled with feathers and one with stones. The feather box is light and the stone box is heavy — the feather box is less dense.

Simple experiment: With an adult, fill a bowl with water. Drop a small stone (it will sink) and a small piece of wood (it will float). Try an orange: with skin it may float; if you peel it, it might sink because peeling changes how air is trapped and changes density.

Real-life examples

Boats made of metal can float because their shape traps air, making the overall density low.
Oil floats on water in a bottle because oil is less dense.

6. ACID AND ALKALI (SIMPLE)

Some liquids are acidic and some are alkaline (also called basic). We can test them with litmus paper or natural indicators like red cabbage juice.

How to recognise acids and alkalis

Acids: Often taste sour. Examples: lemon juice and vinegar.
Alkalis: Feel slippery and can taste bitter (do not taste cleaning products!). Examples: soap water and baking soda dissolved in water.
Neutral: Pure water is neutral (neither acid nor alkali).

Safe activity: Use food items only. With adult help, dip a small piece of red cabbage leaves in boiling water to make purple cabbage water (this is a safe natural indicator). Put a drop of lemon juice in one cup of the cabbage water and baking soda solution in another cup. Watch the colour change: acids and alkalis make the indicator change colour in different ways.

Notes and safety

Never taste or touch strong acids or cleaning chemicals. Always do experiments with an adult and use only safe household items in these notes.

7. THE SOLAR SYSTEM

Our Solar System has a star called the Sun at its centre and eight planets that move around it. The Sun gives light and heat which makes life on Earth possible.

The eight planets — easy order

Mercury — closest to the Sun, very hot during day and very cold at night.
Venus — hot and covered by thick clouds.
Earth — our home, has water and life.
Mars — the red planet.
Jupiter — the largest planet.
Saturn — has rings made of ice and rocks.
Uranus — tilted on its side.
Neptune — very far and very cold.

Other objects and movement

The Moon orbits Earth and reflects the Sun’s light (the Moon does not make its own light).
Asteroids are rocks that orbit the Sun mostly between Mars and Jupiter.
Earth takes one year (365 days) to go around the Sun. Earth spins once each day (24 hours). This spin makes day and night.

Example activity: Use a lamp as the Sun and a small ball as Earth. Move the ball around the lamp slowly to see how a year works. Spin the ball slowly to show day and night.

8. MACHINES — SIMPLE MACHINES AROUND US

Machines help people do work with less effort. Many machines are made from simple parts called simple machines.

Types of simple machines and easy examples

Lever: A bar that helps lift heavy things. Example: seesaw, spade.
Wheel and axle: The wheel helps things roll easily. Example: bicycle wheel, pencil sharpener.
Pulley: A rope and a wheel that helps lift things. Example: flag pulley.
Inclined plane: A ramp that helps move things up. Example: a ramp to load heavy boxes into a truck.
Screw: A twisted ramp wrapped around a cylinder. Example: jar lid, screws that hold wood together.
Wedge: A tool with a sharp edge that cuts or splits. Example: knife, axe.

Combination machines: A wheelbarrow uses a wheel (wheel and axle) and a handle (lever). A pair of scissors uses two levers joined together.

Extra revision facts — short and important (memorise these)

Plants make food in their leaves — this is called photosynthesis.
Air is needed by both people and animals to breathe; plants give out oxygen during the day.
Water has three states: solid (ice), liquid (water) and gas (steam).
Gravity pulls objects toward the ground.
Sound travels in waves through air, water and solids.
Electricity flows in a complete circle called a circuit.

Simple experiments & observations you can do (with adult supervision)

These are safe and use household items. Do them with an adult and write what you see.

Floating and sinking test: Fill a basin with water. Try a coin, a small plastic toy, a leaf, and a small wooden block. Which float and which sink? Write why you think that happens.
Plant growth observation: Put two small pots with soil and plant the same seed in both. Water one pot daily and the other less often. Which grows better? Keep a simple diary with day-by-day notes.
Dissolving sugar: Put a spoon of sugar in cold water and one in hot water. Which dissolves faster? Why might that be?
Shadow experiment: On a sunny day, place a toy on the floor and trace its shadow every hour. Observe how the shadow changes length and direction.
Safe acid/alkali indicator (food items only): With adult help, make cabbage indicator (boil red cabbage leaves and use the purple water). Test lemon juice and dilute baking soda solution. Record colour changes.

How to prepare the night before and the morning of exam

Read this sheet once more — do not try to learn everything new tonight.
Get a good night's sleep. A clear brain remembers better than a tired one.
Eat a healthy breakfast on the exam day (porridge, eggs or fruits).
Read questions carefully, answer the easy ones first, and check your work if time remains.

Quick Test — 30 MCQs (Multiple Choice Questions)

Try these questions on your own. Choose A, B, C or D for each question. The answer key is at the bottom of the page.

Which organ helps us breathe?
A. Heart B. Lungs C. Stomach D. Brain
Which of these is a mammal?
A. Frog B. Shark C. Cat D. Eagle
What part of the plant makes food?
A. Root B. Stem C. Leaf D. Seed
Which unit do we use to measure length?
A. °C B. kg C. meter D. tick
Which object will usually float on water?
A. Stone B. Metal spoon C. Piece of wood D. Coin
Which is an example of an acid found in the kitchen?
A. Soap B. Lemon juice C. Baking soda D. Water
Which planet is called the red planet?
A. Venus B. Mars C. Mercury D. Jupiter
What does a lever help us do?
A. Make sounds B. Break light C. Lift heavy objects D. Make food
Which part of the body pumps blood?
A. Lungs B. Heart C. Brain D. Liver
Which animal breathes using gills?
A. Bird B. Cat C. Fish D. Dog
What do plants need for photosynthesis?
A. Sunlight, water and air B. Soil only C. Sugar D. Salt
Which tool helps you measure time?
A. Ruler B. Thermometer C. Clock D. Scale
Which of these is a simple machine?
A. Television B. Lever C. Book D. Pillow
Where does a seed grow into a new plant?
A. In a pot of soil B. In the sky C. On a rock D. On water
Which of these is sticky and can be used as glue?
A. Water B. Honey C. Oil D. Sand
Which sense helps you taste food?
A. Eyes B. Nose C. Skin D. Tongue
Which is not a state of water?
A. Solid B. Liquid C. Gas D. Plasma
Which part protects the brain?
A. Rib B. Skull C. Spine D. Jaw
Which material would be a poor conductor of heat?
A. Metal B. Wood C. Copper D. Iron
What causes day and night?
A. Moon moving around Earth B. Earth rotating on its axis C. Sun turning off D. Wind
Which of these is produced by burning wood?
A. Salt B. Smoke C. Water D. Ice
What do we call materials such as sugar or salt when they disappear in water?
A. Melted B. Dissolved C. Broken D. Baked
What does a thermometer measure?
A. Size B. Mass C. Temperature D. Length
Which gas do humans need to breathe?
A. Carbon dioxide B. Helium C. Oxygen D. Hydrogen
Which planet do we live on?
A. Mars B. Earth C. Jupiter D. Venus
Which of these is an insect?
A. Spider B. Butterfly C. Crab D. Snake
What is the main source of heat and light for our Solar System?
A. Moon B. Earth C. Sun D. Stars
Which is a function of the roots of a plant?
A. Make seeds B. Absorb water C. Make leaves D. Attract insects
Which item is used to lift water from a well? (Simple machine)
A. Lever B. Pulley C. Wheelbarrow D. Wedge
What should you do first when you touch something hot?
A. Wait B. Move your hand away quickly C. Put your hand back D. Close your eyes