Starter quiz
- What are the key components that make up rocks?
- plastic
- water
- fossils ✓
- shells ✓
- crystals ✓
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- Match the following rock types with their descriptions.
- igneous rocks⇔contain crystals that point in many directions ✓
- sedimentary rocks⇔contain grains that are stuck together and may contain fossils ✓
- metamorphic rocks⇔contain large crystals that all line up ✓
- A mineral is a ______ substance with a crystal structure, while a rock consists of one or more minerals or rock fragments.
- 'pure' ✓
- Which of the following is evidence that supports the idea of tectonic plates moving?
- volcanic eruptions and rock formations ✓
- lightning storms and wind patterns
- ocean tides and river flows
- cloud formations and rainfall
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- ______ rocks have spaces between grains, allowing water to pass through.
- 'porous' ✓
- Which of the following features is commonly found in igneous rocks?
- fossilised leaves
- aligned crystals
- randomly oriented crystals ✓
- layered grains
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Exit quiz
- Which of the following is the correct name for molten rock that has broken through Earth's crust?
- magma
- lava ✓
- intrusive
- extrusive
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- Which of the following is a type of igneous rock that forms inside Earth's crust?
- extrusive
- intrusive ✓
- lava
- magma
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- Which of the following factors determines the size of crystals in igneous rocks?
- the type of minerals present
- the rate at which the molten rock cools ✓
- the depth of the magma
- the type of tectonic plate boundary
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- Sort the following steps into the correct order to describe how the melting of rock at the edge of a tectonic plate leads to the formation of extrusive igneous rock (e.g. basalt).
- 1⇔Some rock at the edge of a tectonic plate could melt.
- 2⇔It becomes magma.
- 3⇔Magma can break through Earth’s surface at a volcano.
- 4⇔It becomes lava.
- 5⇔Lava cools quickly on the surface.
- 6⇔It forms rock with crystals.
- 7⇔The crystals are usually very small.
- Which of the following is an example of an intrusive igneous rock?
basalt
sandstone
marble
granite ✓
- ______ is the process in which solid crystals form as molten rock cools.
- 'crystallisation' ✓
Worksheet
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Lesson Details
Key learning points
- 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.
Common misconception
Some think all lavas/magmas are the same and the type of igneous rock formed depends on cooling rate.
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.
Keywords
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.
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