Year 8 - Science
Igneous rock
Earth's resources
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit explores Earth's composition, structure, and rock cycle, including the formation of igneous, sedimentary, and metamorphic rocks. It also examines Earth as a source of limited resources and the importance of recycling, alongside skills in making and evaluating observations and measurements.
Lesson Summary
You will learn to explain how igneous rocks form and describe features of different types.
Key Notes
- The melting point of rock is very high.
- Melted rock is called either lava (on Earth's surface), or magma (underground).
- Extrusive igneous rock forms outside Earth's crust, while instrusive igneous rock forms inside the crust.
- Some substances form crystals when they freeze.
- Crystal size depends on the rate at which melted rock cools.
Vocabulary To Learn
- lava: Molten (i.e. melted) rock that has broken through Earth's crust.
- magma: Molten (i.e. melted) rock beneath the Earth's surface.
- crystallisation: A process in which solid crystals form as molten rock cools.
- extrusive: A type of igneous rock that form when lava has cooled and crystallised; they form above Earth's surface.
- intrusive: A type of igneous rock that form when magma has cooled and crystallised; they form under Earth's surface.
Common Mistakes To Avoid
- Some think all lavas/magmas are the same and the type of igneous rock formed depends on cooling rate.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
The melting point of rock is very high. Melted rock is called either lava (on Earth's surface), or magma (underground).
2. Define this scientific word and use it in context. 'lava'
Molten (i.e. melted) rock that has broken through Earth's crust. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Some think all lavas/magmas are the same and the type of igneous rock formed depends on cooling rate. Correction: Stress that the type of igneous rock formed depends upon the mineral composition of the lava/magma *and* the rate of cooling. Use examples to reinforce this.
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