PSLE Science flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Life process check

To decide if something is alive, test whether it needs air, water and food, grows, responds to changes, and reproduces. It is living only if all are true.

Characteristics of living things

Living things need air, water and food, grow, move by themselves, respond to changes around them, and reproduce. Non-living things fail at least one of these checks.

Classifying with a key

A classification key asks a series of yes-or-no questions about observable features. Each answer narrows the group until only one kind of object remains.

Solid properties

A solid has a fixed shape and a fixed volume. It does not flow to take the shape of its container, and it cannot be squeezed into a smaller space.

Liquid properties

A liquid has a fixed volume but no fixed shape. It flows and takes the shape of its container, and its surface stays level when the container is still.

Gas properties

A gas has no fixed shape and no fixed volume. It spreads to fill any container and can be compressed into a smaller space, unlike a liquid or solid.

Melting and freezing

Melting is a solid changing to a liquid when heated. Freezing is a liquid changing to a solid when cooled. Pure ice melts at 0 degrees Celsius.

Evaporation and condensation

Evaporation is liquid water changing to water vapour, which happens faster when warm, windy or exposed. Condensation is vapour cooling back into liquid droplets on a cold surface.

Boiling point of water

At normal air pressure, water boils at 100 degrees Celsius. While boiling, the temperature stays at 100 degrees Celsius until all the water has turned to vapour.

What a force does

A force is a push or a pull. It can start an object moving, stop it, speed it up, slow it down, change its direction, or change its shape.

Friction direction and size

Friction acts in the direction opposite to motion. It is larger on rough surfaces and smaller on smooth or oiled surfaces, and it warms the surfaces.

Magnetic materials

Only iron, steel, nickel and cobalt are attracted by a magnet. Copper, aluminium, plastic, wood and glass are not magnetic and are never pulled by a magnet.

Magnet poles

Every magnet has a north pole and a south pole. Like poles push apart, unlike poles pull together, and the pull is strongest at the poles.

Light travels straight

Light travels in straight lines unless it hits a surface. This is why an opaque object placed in a light beam makes a sharp shadow behind it.

Opaque, translucent, transparent

A transparent material lets most light through so objects behind are seen clearly. A translucent material lets some light through. An opaque material blocks all light and makes a shadow.

Heat moves to cooler places

Heat always flows from a hotter object to a cooler one until both reach the same temperature. It never flows on its own from cold to hot.

Good and poor conductors

Metals such as copper, iron and steel conduct heat well. Wood, plastic, rubber and air conduct heat poorly, so they are used as handles and insulators.

Water cycle steps

Water evaporates from seas and lakes when heated by the Sun, rises, cools and condenses into clouds, then falls as rain and flows back to the sea.

Plant needs for growth

Green plants need light, water, air (carbon dioxide) and mineral salts from the soil. They make their own food in their leaves using light energy.

Plant parts and jobs

Roots absorb water and minerals and anchor the plant. The stem carries water upward. Leaves make food using light. Flowers produce fruits and seeds.

Seed germination needs

A seed germinates when it has water, air and a suitable warm temperature. Light is not needed for most seeds to germinate, though seedlings need light later.

Food chains

A food chain shows who eats whom, starting with a green plant that makes food. Arrows point from the food to the eater. All chains begin with the Sun's energy.

Producers, consumers, decomposers

Producers are green plants that make food. Consumers eat other living things. Decomposers such as bacteria and fungi break down dead matter and return nutrients to the soil.

Adaptations for survival

An adaptation is a body feature or behaviour that helps an organism survive. Examples are thick fur in cold places, gills for breathing underwater, and spines on a cactus.

The human digestive path

Food passes from the mouth to the gullet, stomach, small intestine and large intestine. Most nutrients are absorbed through the small intestine's walls into the blood.

Circulation and breathing

The heart pumps blood through tubes called blood vessels. Blood carries oxygen and food to the body. Lungs take in oxygen and remove carbon dioxide.

Skeleton and muscles

The skeleton supports the body, protects organs such as the brain and heart, and works with muscles to move bones at joints. Muscles pull; they cannot push bones.

Electric circuit rule

A simple circuit needs a cell, connecting wires and a component such as a bulb, joined in one unbroken loop. A gap anywhere stops the current and the bulb goes out.

Series and parallel bulbs

In a series circuit, bulbs form one loop, so removing one bulb breaks the circuit. In a parallel circuit each bulb has its own branch and stays lit.

Conductors of electricity

Metals such as copper and iron let electricity pass and are conductors. Plastic, rubber, wood and dry string do not, so wires are covered with plastic for safety.

Sound needs a medium

Sound is made when something vibrates. It travels through solids, liquids and gases but cannot travel through empty space, so there is no sound in a vacuum.

Pitch and loudness

A faster vibration gives a higher pitch and a slower one gives a lower pitch. A larger vibration gives a louder sound and a smaller one gives a softer sound.