1. A teaching sequence from the Catastrophe unit
Etna
Activity 3 Rock
A teaching sequence from the Catastrophe unit
cracking science!
version 1.0
Activity from the Catastrophe unit © upd8 wikid, built by cracking science 2009
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2. To learn how igneous rocks are formed.
To work out which is the best type of igneous rock for a lava barrier.
To discover reasons for igneous rocks’ different properties. 2 2

3. Cat – Bought you some stones from Etna shop today
Cat – Bought you some stones from Etna shop today. Smooth and shiny, just like you... Pedro x
Engage 3 3

4. Any idea what they’re made from?
Right. Check out Pedro’s stones. Beautiful, yes?
discuss
Elicit 4

5. The stones were formed from 100% Etna magma.
Magma is that hot, liquid rock from under the surface. When it cools, it freezes into solid rock.
Rocks from cooled down magma are called igneous rocks.
Elicit 5

6. OK. Time to go back to Antonio.
See you later!
Explore 6

7. Predicting lava flow is all very well.
But what if the lava is approaching a town?
We need to stop it, or divert the flow.
Explore 7

8. Any suggestions? Let’s work on lava barriers.
What material shall we make them from? Best if it’s something we can find nearby.
Any suggestions?
discuss
Explore 8

9. OK. We’ll look at rocks made from cooled down magma – igneous rocks.
Test their properties and report back. Which is best for barriers?
Explore 9 SS

10. Thanks. OK. Back to your training. Just one more thing.
Like I said, we need a rock that’s available here on Etna. And that’s basalt.
OK. Back to your training.
Explore 10

11. Why so much basalt here on Etna
Why so much basalt here on Etna? Why not granite, or another igneous rock?
They’re all made from cooled down magma…
…Let’s investigate.
Explore 11
SS3

12. What did you find out? How does the cooling speed affect crystal size?
discuss
Explore 12

13. Right. The quicker salol cools, the smaller the crystals.
But why? And what’s this got to do with igneous rocks?
Explain 13

14. The same happens to magma.
If salol cools slowly, the particles have longer to arrange themselves in a pattern. Big crystals form.
The same happens to magma.
Explain 14

15. The same happens to magma when it cools quickly.
Quick cooling makes small crystals – the particles have less time to make a pattern.
The same happens to magma when it cools quickly.
Explain 15

16. Can you figure out why magma sometimes cools slowly, and sometimes fast?
discuss
Elaborate 16

17. discuss
Elaborate 17

18. Some magma cools under the Earth’s surface.
magma cooling slowly
area where cooled magma has formed rock
The surrounding rocks insulate the magma. So it takes a long time to cool down.
Elaborate 18

19. The crystals have time to grow big.
Granite is an example of a rock that was formed under the surface.
Elaborate 19

20. When magma leaves a volcano, we call it lava.
Lava cools quickly in cool air or under water.
Elaborate 20

21. Rocks from quickly cooled lava have small crystals, just like Etna’s basalt.
Elaborate 21

22. Any idea what might make lava cool very quickly?
Sometimes the lava cools so quickly that crystals don’t have time to form at all.
That explains bubbly pumice and glassy obsidian.
Any idea what might make lava cool very quickly?
discuss
Elaborate 22

23. One last thing… Now you know all about igneous rocks…
Let’s take another look at Pedro’s stones.
Evaluate 23

24. So they are a type of rock called…
They are made from…
So they are a type of rock called…
They contain small crystals. This shows that…
I think the name of the rock is…
Evaluate 24

25. Cat – Just saw Letizia and Antonio looking v. worried
Cat – Just saw Letizia and Antonio looking v. worried. Do they know something we don’t?
Ped xxx
Evaluate 25 25

26. Picture credits Picture Slide Credit
Basalt Breccia 9 commons.wikimedia.org
Salol crystals after slow cooling 14 SPL – Martyn F. Chillmaid
Salol crystals after fast cooling 15 SPL – Martyn F. Chillmaid
Igneous structures 17 commons.wikimedia.org
Pahoehoe toe 20 commons.wikimedia.org
Hand sample of Basalt 21 SPL – Mark A. Schneider