Earth and Space
What you must understand
Candidates must describe the structure of the Earth (crust, mantle, outer core, inner core) and relate it to earthquakes, volcanoes and plate movement. Know the rock cycle and the three rock types: igneous, sedimentary and metamorphic, with one example of each. Understand soil formation and composition. Know the water cycle stages: evaporation, transpiration, condensation, precipitation and run-off. Understand the Solar System: the Sun as a star, planets orbiting it, moons, and the causes of day and night, seasons and phases of the Moon. Know that the Moon orbits Earth and Earth orbits the Sun.
Traps that appear in questions
- Saying seasons are caused by Earth being closer to the Sun; they are caused by the tilt of Earth's axis.
- Explaining day and night by Earth orbiting the Sun; it is Earth's rotation on its axis.
- Confusing the phases of the Moon with Earth's shadow; phases are about how much lit side we see.
- Placing the mantle outside the crust in the wrong order, or calling the core liquid throughout.
- Thinking sedimentary rock forms from melting; it forms from compacted deposited layers.
- Confusing weathering (breaking down in place) with erosion (transport of material).
Rule of thumb and worked example
Use the order "Crust, Mantle, Outer core, Inner core" from outside in, and remember rotation gives day and night while tilt gives seasons.
Example: Botswana has long hot days in December. This is not because Earth is nearest the Sun then; it is because the southern hemisphere is tilted towards the Sun, so sunlight strikes more directly and days are longer. In June the same tilt points the southern hemisphere away, giving shorter, cooler days.