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A testable prediction based on evidence or prior knowledge.

Independent variable (IV), Dependent variable (DV), Controlled variable (CV).

The variable the scientist deliberately changes.

The variable that is measured — it depends on the IV.

Only ONE variable changes at a time; all others are kept the same.

Metre (m).

Kilogram (kg).

Degrees Celsius (°C) or Kelvin (K).

For categorical (discrete) data — e.g. favourite colours, types of rock.

For continuous data that changes over time.

Qualitative = words (descriptions). Quantitative = numbers (measurements).

Observation = what you see/measure (fact). Inference = a conclusion drawn from observations.

Safety goggles, lab coat, gloves, fire extinguisher, eye wash station.

Repeating improves reliability. One result could be a fluke — multiple trials show if the pattern is consistent.

You can't tell which variable caused the change. A fair test changes only ONE variable so you know what caused any difference.

Accuracy = how close to the true value. Reliability = how consistent results are when repeated. You can be reliable but inaccurate.

All matter is made of tiny particles that are always moving.

Close together in a regular, fixed pattern. Particles vibrate in place.

Close together but able to slide over each other. No fixed pattern.

Far apart, moving quickly in random directions. Lots of empty space.

Solid → Liquid. Particles gain energy and break free of their fixed positions.

Gas → Liquid. Particles lose energy and move closer together.

Solid → Gas directly (skipping liquid). Example: dry ice (solid CO₂).

Particles gain kinetic energy and move faster.

Two or more substances physically combined but not chemically joined.

Solute = the substance that dissolves. Solvent = the liquid it dissolves in.

Filter paper traps insoluble solid particles while the liquid passes through.

Heating the solution evaporates the water, leaving the solid behind.

Separating mixtures of dyes or inks — different colours travel different distances on paper.

A solution where no more solute can dissolve at that temperature.

Freezing.

Particles DON'T get bigger. They move faster and spread further apart. The GAPS between particles increase, not the particles themselves.

Your body heat (37°C) is above chocolate's melting point (~34°C). Heat energy transfers to the chocolate, making particles vibrate faster until they break free of their fixed positions.

Diffusion — perfume particles spread out from high concentration to low concentration through the air. Gas particles move randomly in all directions.

Crust → Mantle → Outer Core → Inner Core

The mantle (~2,900 km thick).

Extreme pressure from all the layers above keeps it solid.

Oceanic crust is thin (5–10 km) and dense. Continental crust is thick (30–70 km) and less dense.

Heat from the core (radioactive decay). Hot rock rises, cools, sinks, and the cycle repeats.

Convection currents in the mantle.

Divergent (apart), Convergent (together), Transform (sideways).

Plates move apart. Magma rises to fill the gap, creating new crust (sea-floor spreading).

When a denser oceanic plate sinks beneath another plate at a convergent boundary.

A supercontinent ~300 million years ago when all land was joined together.

Matching fossils across continents, coastline shapes fit together, matching rock types, tropical fossils in cold regions.

He had no mechanism — he couldn't explain HOW the continents moved.

A zone around the Pacific Ocean with ~75% of the world's volcanoes and ~90% of earthquakes.

Core heat → convection currents → plate movement → surface features.

Transform boundaries — they only produce earthquakes.

Plates push against each other for years, building up pressure. When the friction is overcome, they slip suddenly — releasing all that stored energy as an earthquake.

The mantle is mostly SOLID rock, but it flows very slowly (like thick honey) due to extreme heat and pressure. It's semi-solid, not liquid.

Both happen at plate boundaries where plates interact. The same forces that cause plates to collide (volcanoes) also cause them to slip (earthquakes).

A community of living things interacting with their non-living environment.

Biotic = living (plants, animals). Abiotic = non-living (temperature, water, light).

An organism that makes its own food via photosynthesis. Example: grass, trees, algae.

Energy is transferred to — it shows the direction of energy flow.

Only ~10% of energy is passed to the next level — the rest is lost as heat.

Many interconnected food chains in an ecosystem.

Structural (body features), Behavioural (actions), Physiological (body processes).

Camel's hump (stores fat), polar bear's thick fur, cactus spines.

Bird migration, hibernation, nocturnal hunting.

The variety of different species in an area.

It makes ecosystems more stable and resilient — if one species declines, others can fill the gap.

Deforestation, pollution (air/water/land), overfishing, burning fossil fuels.

An organism that breaks down dead matter, recycling nutrients. Examples: fungi, bacteria, earthworms.

Prey population increases → they overeat their food source → food source declines → knock-on effects.

Dead organisms would pile up. Nutrients would be locked in dead matter and never recycled back to the soil. Plants would eventually run out of nutrients and die.

Most organisms eat multiple things and are eaten by multiple predators. A chain shows just one path; a web shows the real complexity of feeding relationships.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Inner = small, rocky (Mercury, Venus, Earth, Mars). Outer = large, gaseous (Jupiter, Saturn, Uranus, Neptune).

A medium-sized star made of hydrogen and helium, producing energy through nuclear fusion.

365.25 days (one year). The extra 0.25 gives us a leap year every 4 years.

About 27.3 days.

We see different amounts of the sunlit side as the Moon orbits Earth.

Earth's 23.5° axial tilt — different hemispheres receive more/less direct sunlight at different times.

When one hemisphere is most tilted toward (summer solstice, longest day) or away from the Sun (winter solstice, shortest day).

Earth's rotation on its axis once every 24 hours.

Winter — the hemispheres have opposite seasons.

When the Moon passes between the Sun and Earth, blocking sunlight.

When Earth passes between the Sun and Moon, casting a shadow on the Moon.

Between Mars and Jupiter.

Any object orbiting a planet — natural (the Moon) or artificial (GPS, ISS).

Neil Armstrong, July 20, 1969 (Apollo 11).

Earth's 23.5° tilt means when the Northern Hemisphere tilts AWAY from the Sun (winter), the Southern Hemisphere tilts TOWARDS it (summer). Opposite seasons.

The Moon rotates on its axis in exactly the same time it takes to orbit Earth (~27 days). This is called tidal locking.

Earth's distance from the Sun barely changes. Seasons are caused by the TILT of Earth's axis (23.5°), which changes the angle and duration of sunlight.