Primary 4 Science

A disease caused by pathogens that can pass from person to person, such as flu.

Tiny living things that cause illness, such as viruses and bacteria.

A pathogen even smaller than bacteria, such as the flu virus, which can only multiply inside living cells.

A single-celled microbe; some kinds cause illness, such as the cholera vibrio.

Tiny drops spat out when we cough, sneeze or talk; they can carry pathogens.

A living thing that carries pathogens to people, such as mosquitoes that spread dengue fever.

A preparation put into the body so it builds resistance and is protected against a specific disease.

Unusual signs the body shows when ill, such as fever, cough and headache.

A gut disease caused by the cholera vibrio and spread through unsafe food and water.

The body's power to fight germs and keep itself from falling ill.

A disease that does not pass between people, such as heart disease.

A disease of the heart or blood vessels; fat building up inside vessels makes blood hard to reach the heart.

The blood vessel that supplies the heart muscle; when blocked it causes heart disease.

A disease in which body cells grow abnormally without stopping.

Breathing in tobacco smoke; it harms vessels and lungs and causes many diseases.

Putting a vaccine into the body so it builds resistance against infectious diseases.

Regular examination of the body so illness is found and treated early.

An infectious disease first found in 2019 that spread worldwide; scientists quickly developed vaccines and tests for it.

Measures that handle pathogens and samples safely to stop disease from spreading.

Eating a balance of foods with less fat, salt and sugar.

The process by which living things produce young and continue their kind.

The carrying of pollen from the stamen to the stigma.

The joining of pollen with an ovule, after which fruit and seeds form.

Seeds carried far away by wind, water or animals to sprout and grow.

Growing new plants from food-storing roots or stems, such as sweet potatoes and onions.

A body feature passed from parents to children, such as eye colour.

A feature formed after birth, such as hair length; it is not inherited.

The next generation produced by living things.

Animals that feed their young with milk, such as cats, dogs and whales.

The ability to curl the tongue into a tube; a common example of an inherited trait.

Features or behaviours that help a living thing survive in its environment.

A hot, rainy environment full of dense plants, such as the Amazon rainforest.

A wide grassy land with clear dry and wet seasons; its animals run fast.

The freezing, ice-covered lands at the north and south ends of the Earth.

A dry land with little rain and big day-night temperature swings.

The long seasonal journey of animals to a better place to live.

Hiding through winter with the body slowed down, as snakes and frogs do.

A chain of who eats whom, such as grass → rabbit → eagle.

A plant that makes its own food; the start of every food chain.

A predator hunts other animals; the one hunted is called the prey.

A shiny material that conducts electricity and heat, such as copper, iron and aluminium.

A material that usually does not conduct electricity and conducts heat slowly, such as wood, plastic and glass.

Heat travelling along an object from the hot end to the cool end.

How well a material lets current pass; copper conducts very well.

A metal that conducts both electricity and heat well, used for wires and cookware.

A hard, heat-conducting metal used for woks and construction.

A material that conducts heat very slowly, such as wood, plastic and air, used to block heat.

A light metal that hardly rusts, used for cans and window frames.

A light man-made material that conducts heat slowly, used for handles and casings.

The part of a utensil held by hand, usually made of insulating material.

A change of shape or state that makes no new substance.

A change that creates a new substance, such as rusting and burning.

A solid turning to liquid when heated, such as ice melting into water.

A material spreading into a liquid until it cannot be seen, like sugar in water.

A liquid slowly turning to gas and drifting away, like wet clothes drying.

Iron reacting with oxygen and water in the air to grow reddish-brown rust — a chemical change.

A substance reacting quickly with oxygen, giving out light and heat — a chemical change.

Food broken down by microbes and going bad — a chemical change.

A material formed by a change, with properties different from the original.

Able to be undone by simple means, like ice melting to water and freezing back.

A resource that gives us usable energy, such as coal and sunshine.

Energy from the sun's light and heat; it never runs out.

Energy made when wind turns wind turbines to generate electricity.

Energy made from the power of flowing water.

A black fossil fuel buried underground; burning it makes electricity.

An oily fossil fuel from underground, refined into petrol and other products.

A gaseous fossil fuel underground; burning it for power is cleaner than coal.

The collective name for coal, oil and natural gas, formed from ancient life and running out.

Making electricity from different energy sources.

Using energy wisely and wasting less, such as switching off lights when leaving a room.

An object that glows by itself, such as the sun and a switched-on torch.

Light striking a surface and bouncing back.

Light bounced off an object; moonlight is reflected light.

An object with a smooth surface that reflects light into a clear image.

The picture formed by reflection in a mirror or on water.

The dark area behind an object that blocks the light.

The body circling the Earth; it does not glow but is seen by reflecting sunlight.

An ancient tool that tells time from where the pin's shadow falls in the sun.

Light moves in straight lines; blocked, it leaves a shadow.

A flat, slick surface that reflects light especially well.

The complete closed pathway that current follows.

A circuit joined everywhere so current can circulate.

A circuit with a break somewhere, so current cannot pass.

The flow of electricity around a circuit that makes appliances work.

A power source with a positive and a negative terminal.

A line that carries current, usually copper inside and insulating plastic outside.

An appliance that turns electric energy into light, with two contact points.

A device that opens and closes the circuit.

A material that lets current pass, such as copper and iron.

A material that blocks current, such as plastic and rubber, used to protect us.

The thin, hard outermost layer of the Earth, like the shell of an egg.

The thick layer beneath the crust, made of very hot, slowly flowing rock.

The very centre of the Earth, extremely hot — the heart of our planet.

Rock formed when magma cools and hardens, such as granite.

Rock formed from layers of sand and mud pressed together over long years, such as sandstone.

Rock changed by great heat and pressure, such as marble.

The slow breaking up of rock by wind, rain, sun and frost.

Rotted leaves and remains of living things that enrich the soil.

Soil with fine, tightly packed particles; it holds much water but roots spread with difficulty.

Soil with a balanced mix of sand and clay; it holds water and nutrients and is best for planting.

The state of the air in a place over a short time, such as today's sunshine, rain, heat or cold.

The average weather pattern of a place observed over many years.

How hot or cold the air is, measured with a thermometer.

The depth of rain that falls over a period, measured with a rain gauge.

The amount of water vapour in the air; high humidity feels sticky.

A tool for measuring how hot or cold the air is.

A tool for measuring rainfall, like a graduated cylinder.

A tropical storm with fierce wind and heavy rain, common in Hong Kong in summer and autumn.

A place that is dry all year with little rain and a big difference between day and night temperatures.

Information and forecasts about the weather issued from observation data.

The Earth spinning on its own axis once about every 24 hours, causing day and night.

The Earth travelling around the Sun once about every 365 days; with the tilted axis it causes the seasons.

The imaginary line the Earth spins around, tilted about 23.5 degrees.

The two halves of the Earth divided by the equator; their seasons are opposite.

Spring, summer, autumn and winter, caused by revolution and the tilted axis.

Gases such as carbon dioxide that trap heat and warm the Earth.

The rise of the Earth's average temperature as greenhouse gases build up.

Huge, slow-moving ice in high mountains and polar regions; warming melts it.

Land slowly turning into desert through drought and damage.

The greenhouse gases such as carbon dioxide that human activities give off.

Looking carefully and recording things with our senses in an organised way.

A guess about the result, based on observation and experience.

A test in which only one condition changes while all others stay the same.

A condition that can change in an experiment; a fair test changes only one each time.

Observations and data that support or overturn a conclusion.

The answer reached after analysing the evidence.

Writing down or drawing observations and data truthfully.

The ability to form new ideas in the mind; scientists need it too.

The old idea that the Earth is a flat sheet.

The evidence-based understanding that the Earth is a sphere.

A craft made and launched by people that orbits the Earth.

Using signals from navigation satellites to find where you are.

A satellite that photographs clouds and watches the weather from space.

Finding direction and a route; phone maps use satellites to navigate.

A vehicle that carries people or goods to space, such as the Shenzhou spacecraft.

A person trained to travel into space to carry out missions, also called a space traveller.

A lab orbiting Earth where people live and work, such as Tiangong.

The state in space of seeming to have no weight; water floats as drops.

Our nation's Moon missions; the probes landed on the Moon and brought back lunar soil.

The science and technology for exploring space, much of it now used in daily life.

The steps engineers follow: plan, build and test, improve, then share and reflect.

The process repeats in cycles so the design keeps getting better.

The first model built for testing.

Material that slows heat transfer, such as foam and bubble wrap.

Material that lets heat pass easily; metal is a common example.

Tiny pockets of air inside a material; air conducts heat poorly, so it insulates.

The cover of a container that keeps hot air from escaping.

The numbers measured in a test, such as the water temperature every five minutes.

The requirement that judges success, such as no more than five degrees lost in fifteen minutes.

To change the design based on test results to make it better.