Download Year 8 Activity Pack sample - UNIT 8HB

8
Igneous and
metamorphic rocks
Hb-1
These sentences describe igneous and metamorphic rocks and the way they are formed.
Cut out the cards and match them up to form complete sentences.
Arrange them in a sensible order. Ask your teacher to check them and then stick them into
your book.
I can…
●
describe how igneous and metamorphic rocks are formed
●
recall how the grain size depends on cooling.
A We live on the Earth’s crust …
B … it forms igneous rocks.
C If the magma cools slowly …
D … this molten rock is called magma.
E … and the layer below the crust is the
mantle.
F When magma cools down again …
G … igneous rocks.
H Schist and gneiss are examples of …
I
Metamorphic rocks are existing rocks
that …
J … it forms rocks with small crystals.
K Sometimes rocks get hot enough to melt
and …
L Magma sometimes reaches the surface
of the Earth …
M Gabbro and basalt are examples of …
N Igneous rocks do not have layers …
O … of interlocking crystals.
P … it forms rocks with large crystals.
Q … metamorphic rocks.
R … have been changed by heat or pressure.
S … but metamorphic rocks sometimes
have coloured bands.
T If the magma cools quickly …
U … when it is called lava.
V Igneous and metamorphic rocks always
have a texture …
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8
8
Runny lava 1
Hb-2
Your teacher may watch to see if you can:
●
follow instructions
●
make careful observations.
Introduction
Some lavas are more runny than others. You can use jelly as a model to help you to investigate
how the runniness of lava affects how far it will flow.
Aim
To find out how the distance flowed by a model of lava depends on how runny the model lava is.
Method
Apparatus
Clean up any spills
straight away.
Do not eat the jelly.
●
ramp propped up on books
● metre ruler
●
stopclock
● jelly mixtures
●
measuring cylinder
● cloth (to clean ramp)
●
bucket or bowl
Set up a piece of wood to act as a ramp. Prop up
one end using books.
A Put 10 cm3 of jelly into a measuring cylinder.
B Pour the jelly onto the top of the ramp and start
the stopclock.
C After 10 seconds, measure how far the jelly has
run down the ramp.
D Clean the ramp by wiping the jelly into a bucket.
E Repeat steps A to D with the other jelly mixtures.
Recording your results
1 Copy this table to record your results.
Jelly mixture
How runny?
Distance moved in 10 seconds (cm)
A
Considering your results/conclusion
2 a Which jelly moved furthest in the time?
b Why do you think this jelly moved the furthest?
3 If you had a very long ramp, the jelly would probably still stop before it reached the end of the
ramp. Why would this happen?
4 Explain how the jelly is a model for different kinds of lava.
I can…
●
use a model to investigate a scientific question
●
explain how the runniness of lava will affect how far it will flow.
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9
8
Runny lava 2
Hb-3
Introduction
Lava from some volcanoes is more runny than lava from other volcanoes. The ‘runniness’ of a
liquid is called its viscosity (vis-kos-it-ee). Sticky liquids like treacle have a high viscosity (they are
said to be viscous). Water is very runny. It has a low viscosity.
Aim
To plan and carry out an investigation to find out how the viscosity of lava affects the distance it
flows. You can use mixtures of jelly and water as a model for lava.
Apparatus
●
ramp propped up on books
● metre ruler
● stopclock
●
jelly cubes
● beakers
● warm water
●
measuring cylinder
● bucket or bowl
●
cloth (to clean ramp)
Clean up any
spills straight
away.
Do not eat the
jelly.
Planning
1 Write a plan for your investigation.
You will need to think about these things:
● How steep will your ramp need to be?
● How many different jelly mixes will you use?
● Which variables will you need to control to
make your test fair?
● How will you measure how far each mixture runs?
● Do you need to do any preliminary experiments before writing your final plan?
● How will you make sure your investigation is safe?
Prediction
2 What do you think you will find out? Give reasons for your prediction.
Recording your results
3 Design a table for your results. Show your plan to your teacher, and then carry out
your investigation.
Considering your results/conclusion
4 Which jelly ran the furthest? Was your prediction correct?
5 What does your experiment tell you about lava and volcanoes?
6 How good is the jelly as a model for lava? Explain your answer.
Evaluation
7 Could you improve your method if you had time to do the investigation again?
Explain your answer.
8 Was the way that you measured the flow of the jelly accurate enough?
I can…
●
use a model to investigate a scientific question
●
plan a fair test
●
suggest improvements to my method
●
explain how the runniness of lava will affect how far it will flow.
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purchasing institution only. This material is not copyright free.
10
8
Densities of igneous rocks
Hb-4
Your teacher may watch to see if you can:
●
measure volumes and masses accurately.
Introduction
Igneous rocks are made from different minerals. Some minerals are denser than others, so the
amounts of different minerals in a rock affect the overall density of the rock. The density of a
material is the mass (in grams) of one cubic centimetre (1 cm3) of that material.
density (g/cm3) = mass (g) 3
volume (cm )
Aim
To compare the densities of some igneous rocks and relate their densities to the minerals
they contain.
Method
A Draw up a table for your results. You need columns for
name, mass, volume and density.
Apparatus
●
rock samples: granite, basalt,
gabbro, rhyolite
● large measuring cylinder
(or displacement can, bowl
and measuring cylinder)
● balance
B Find the mass of each sample and record them in
your table.
C Find the volume of each of your rock samples, and record
them in your table.
D Calculate the density of each sample and write it down.
Considering your results/conclusions
1 Write the rocks in order of their densities, starting with the least dense.
2 All of these rocks are igneous rocks. Why do they have different densities?
3 Would you expect the mineral composition of basalt to be more like gabbro or more like
granite? Explain your answer.
Further questions
Granite
Rhyolite
Gabbro
Basalt
coarse
grains
fine
grains
coarse
grains
fine
grains
14%
14%
16%
16%
iron oxides
3%
3%
11%
11%
magnesium oxides
1%
1%
7%
7%
silica
72%
72%
50%
50%
other compounds
10%
10%
16%
16%
Texture of rock
Percentage of
different chemical
compounds found
in each type of rock
aluminium oxides
Data showing chemical and mineral composition of some igneous rocks
4 Does the information in the table support your answer to question 3? Explain your answer.
5 Why do you think granite is described as a silica-rich rock? What evidence is there in the table
to support this description?
6 Why do you think gabbro is described as an iron-rich rock? What evidence is there in the table
to support this?
I can…
●
make careful measurements and calculate results
●
compare the densities of igneous rocks and relate them to the minerals in the rocks.
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purchasing institution only. This material is not copyright free.
11
8
Modelling cooling magma
Hb-5
The shapes below represent the particles in magma. The shapes can be fitted together to form a
model of a crystal.
1 Cut out all the shapes.
2 Working alone or in pairs fit the shapes together again to form a large ‘crystal’.
3 Separate the shapes again, and then see how many you can fit together into a ‘crystal’ in:
a 2 seconds
b 5 seconds
c 10 seconds
d 20 seconds.
4 How does this model help you to think about the size of crystals formed when magma cools
down quickly and when it cools down slowly?
I can…
●
explain how the size of crystals is evidence for the speed of cooling.
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purchasing institution only. This material is not copyright free.
12
8
Disaster warnings!
Hb-6
There are many different kinds of natural disaster, including volcanic eruptions, earthquakes and
landslides. Earthquakes that happen beneath the sea can cause huge waves called tsunamis,
such as the one that devastated parts of the Japanese coast in 2011. Landslides can bury whole
towns, and landslides that fall into the sea, or that happen under water, can also cause tsunamis.
Newspapers and websites often publish stories about disasters that might happen. Your task is to
find several articles about the same disaster and to evaluate them by looking at the kind of
language used and whether they quote trustworthy sources.
Finding articles
Here are some ideas for possible natural disasters you could find out about:
● Canary Island Tsunami. There is a volcano called Cumbre Vieja on La Palma in the Canary
Islands. Some geologists think that when this erupts again it could cause the side of the
volcano to slide into the sea and cause a tsunami that could kill millions of people living on
shores around the Atlantic Ocean.
● You could find out more about the Yellowstone Megavolcano described in the Student Book.
● Mount Vesuvius in Italy is very close to the city of Naples. Vesuvius is an active volcano and
will erupt again.
● The San Andreas Fault runs through California. This is where two parts of the Earth’s crust
meet, and there are frequent earthquakes along it. Some people think that a big earthquake
may happen soon.
Activities
A Find two articles about the same event and compare them in terms of:
● use of emotive language (look particularly at choices of adjectives and verbs)
● whether the articles describe how the information was obtained
● whether they quote any expert sources.
B Find two examples of emotive or exaggerated reporting of a disaster. Rewrite the articles in a
more scientific, factual style.
C Find a serious article about a natural disaster. Write the headline and the first paragraph of an
article for the front page of a tabloid newspaper – make sure people will want to buy the paper
to finish reading your rewritten article.
Hints
● You could start by printing out your article or copying it into a word processing program. Then
highlight all the adjectives in one colour and all the verbs in another. This will help you to look at
emotive language.
● Underline all the parts of the article that are quotes, or things said to the reporter by other
people. Try to identify who gave each quote, and what the article says about their qualifications
to give expert opinions.
I can…
●
identify the use of emotive language in media reports
●
evaluate the information contained in media reports
●
write reports in different styles for different audiences.
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purchasing institution only. This material is not copyright free.
13
8
Rocks and crystals
Hb-7
Name
Class
Date
1 a What ‘C’ is the part of the Earth we live on?
b What ‘M’ is the name for molten rock underground?
c What ‘L’ is the name for molten rock that comes out of the ground?
2 The diagram shows places (A–F) where molten
rock has solidified to form igneous rocks.
a In which two places would the molten rock
have cooled down at the same rate?
b Write places B, D and E in order of how
quickly they would cool down, starting with
the one that would cool the fastest.
When molten rock cools quickly, it forms rocks with small crystals.
3 Write down the name of an igneous rock with
a small crystals
b large crystals
4 Look at the diagram in question 2 again. Write down the letter of one place where you would find:
a rocks with large crystals
b rocks with small crystals
5 Quartzite is a metamorphic rock formed from sandstone. The drawings show the textures of
these two rocks.
a What two processes can change a rock into a metamorphic rock?
b Write the correct names under the
drawings.
c Explain how you worked out your answer.
I can…
●
describe factors that affect the size of crystals in rocks
●
recall the processes that form metamorphic rocks
●
identify the textures of different types of rock.
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purchasing institution only. This material is not copyright free.
14
8
Sills, dykes and plutons
Hb-8
Intrusive igneous rocks are formed when
magma cools down underground. They are
named because the magma has ‘intruded’
into rocks that were already present. Most
intrusive igneous rocks have large crystals,
but not always!
The diagram shows three different ways in
which magma can be intruded. Large
volumes of igneous rock are called plutons.
Sills are thin sheets of igneous rock formed
from magma that was pushed between layers
of rock, and dykes are similar sheets that cut
across layers of rock.
When magma is forced into existing rocks, it
is much hotter than the rocks surrounding it.
Energy is transferred to the surrounding
rocks, and the magma cools down. Thin
sheets of magma have a much bigger surface
area compared to their volume than plutons,
so thin sheets cool down much faster.
1 Why do most intrusive igneous rocks have large
crystals? Explain in as much detail as you can.
2 Which will have the largest crystals – a dyke or
a pluton? Explain your answer.
3 The crystals at the edge of a pluton are usually
smaller than crystals in its centre. Suggest why
this is so.
4 Diagram B shows some intrusive igneous rocks
(black). Which letter or letters show sills and
which show dykes? Explain your answers.
5 The descriptions and pictures below are for three metamorphic rocks. Match up the
descriptions to the pictures by writing pairs of letters. Put the pairs in order, starting with the
rock metamorphosed by the lowest temperatures and pressures.
a Crystals large enough to
be visible to the naked
eye, often in wavy layers.
b Very small crystals in
layers.
c Crystals of various sizes;
some large crystals form
coloured bands.
d
e
f
6 Describe where you might expect to find some metamorphic rocks in Diagram A.
I can…
●
describe some factors which affect the cooling rate of magma
●
explain the variation in crystal size in an igneous intrusion in terms of cooling rate
●
describe how metamorphic rocks are formed.
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purchasing institution only. This material is not copyright free.
15
8
Minerals in igneous rocks
Hb-9
There are many kinds of igneous rock, because igneous rocks can contain different combinations
of minerals and can have different crystal sizes. Many of the names of rocks you have examined
are names of groups of rocks, rather than describing just one combination of minerals.
Geologists use a diagram like the one below to summarise the different combinations of minerals
that are found in igneous rocks. The shaded minerals produce dark-coloured crystals, the
unshaded ones produce light-coloured minerals.
For example, if you examine a rock closely and it has a lot of plagioclase feldspar and pyroxene,
but no quartz, it would be either gabbro or basalt. You would need to look at the sizes of the
crystals to decide which of these rocks it was.
1 a What mineral would gabbro contain in addition to pyroxene and plagioclase feldspar?
b Do you think gabbro was formed from lava or from magma trapped beneath the ground?
Explain your answer.
2 Which types of rock with large crystals can contain the following minerals? (There may be
more than one type of rock for each answer.)
a amphibole
b pyroxene
c muscovite mica
3 Which types of rock with small crystals
do not contain the following minerals?
a olivine
b biotite mica
c quartz
4 a Why are granites and rhyolites
usually fairly pale in appearance?
b Copy and complete the table.
The first two rows have been done
for you.
Composition of granite
Mineral
Minimum
percentage
Maximum
percentage
amphibole
0
8
biotite mica
4
12
muscovite mica
plagioclase feldspar
quartz
potassium feldspar
5 Suggest why geologists use mineral diagrams rather than just a table showing the
compositions of various rocks.
6 Optional extra: Find out where peridotite is found.
I can…
●
use information from data in a chart
●
use information about a rock’s mineral content to identify it.
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purchasing institution only. This material is not copyright free.
16