Vocabulary preview
agents of erosion
atmosphere
deposition
erosion
humus
igneous rock
minerals
non-renewable resource
photosynthesis
renewable resource
resource
sediment
sedimentary rock
weathering
Major Earth resources
3.1
science
Background
pa
Rocks
W h a t is in a r o c k ?
5V
Collect this …
s t e r e o m ic r o s c o p e o r h a n d l e n s
s a m p l e s o f d iffe r e n t r o c k s
e
Do this …
1 C a r e fu l l y s t u d y o n e o f t h e r o c k s a m p l e s w it h
t h e m ic r o s c o p e a t a b o u t 4 0 m a g n ific a t io n
o r w it h a h a n d l e n s . Is t h e m a t e r ia l in t h e r o c k
a l l t h e s a m e o r is t h e r o c k m a d e o f d iffe r e n t
m a t e r ia l s ?
2
Hints and suggestions
Sa
Granite (and other intrusive rocks) should have
clear crystals of quartz, feldspar and micas.
Help students recognise these by colour
and shape. (Quartz is more see through. The
micas, although not always, are often darker
and could appear flaky. Feldspars are less see
through, but also a light colour (often a beige).
Possible results and looking forward
This activity will help students understand how
materials and minerals exist in rocks. It could
be done at the start of the chapter or when
completing the rocks section on page 72.
7 Teacher Companion
• rocks
• minerals and fossil fuels (like coal and oil) found
in rocks
• soil
Record this …
• air
Describe w h a t y o u s a w .
• water
Explain h o w
hu m an s .
• living things
t hes e r o ck s co u ld b e u s ed b y
• sunlight.
Some of these resources are shown in Figure 3.1.1.
68 PEARSONVFLHQFH
Learning strategies
Reading strategy
What is renewable
As they explore this chapter, students
will be clearly told which of the Earth
resources are renewable and which are
non-renewable. Have students complete
a table such as this one as they read.
PEARSON science
The major natural resources of Earth are its:
S t u d y t h e o t h e r r o c k s t o s e e if t h e y h a v e t h e
s a m e m a t e r ia l s in t h e m .
MI: Verbal/Linguistic, Visual/Spatial
68
Natural resources
A resource is anything supplied by the Earth to satisfy
a particular need of humans or other living things.
Most natural resources are substances, such as rocks or
water. However, sunlight is a vital resource that is not a
substance. Sunlight is a form of energy and is needed
by almost all living things on Earth. Though it enters
the Earth from space and is not a substance, it can be
considered to be an Earth resource.
m
pl
The different materials in rocks will be easier to
see in some rocks than in others, depending
on the way in which the rocks have formed.
Igneous rocks that formed under the ground
(intrusive rocks) form slower than those
formed after a volcano or above ground. In
your samples try to include a range of rocks
including granite, basalt and shale. This will
help students to compare the types of rocks.
Granite will be easiest of these three in which
to see the different crystals and materials.
fun
ge
Rocks
s
Humans need many things to
stay alive, like food, air, water
and shelter. Other living things
have similar needs. These
needs are met by the natural
resources on Earth. It is the
responsibility of everyone to
protect these vital resources.
Resource
type
Renewable
or nonrenewable
Water
Renewable
Ocean, lakes,
rain
Rocks
Nonrenewable
Limestone,
sandstone,
granite
…
Examples
Reading strategy
Living things as
a resource
Summaries
Living things are a resource for humans and other
organisms. For instance, animals eat plants and other
animals. Sometimes living things even use other
organisms as places to live. For example, tapeworms live
in the gut of other animals. Plants use waste materials
from animals and other plants as nutrients. Some plants
rely on animals as a way of pollinating flowers, such
as in Figure 3.1.2. Humans use plants and animals for
food, shelter, building materials, clothing, medicines,
fertilisers, fuel and many other purposes.
Before reading, ask students to construct a
table with two columns. The first column
should have the heading ‘Non-renewable
energy sources’ and the second ‘Renewable
energy sources’. As students read, they
should add the energy sources described to
the appropriate column.
MI: Verbal/Linguistic
Helpful hint
Figure
3.1.1
Living things: some time restrictions
apply
Birds, animals, trees, soil, rocks, water, air
and sunlight are resources.
MI: Logical/Mathematical, Verbal/Linguistic
ge
Living things also depend on their surroundings to
supply other resources that they need. Water, rocks, air
and soil supply the materials needed for all life. Sunlight
is also essential for plants to make their own food and to
keep the Earth warm enough for life to exist.
Some crops take out a lot of nutrients and
then other crops can sometimes be used
to help restore those nutrients. Legumes,
for example, are nitrogen fixers and can be
planted to restore nitrogen, but they use up
other nutrients. Have students find out more
about crop rotation in farming.
Living things: a renewable resource
Living things are a renewable resource because they
reproduce. A forest that has been cut down can regrow.
Animals like the cows in Figure 3.1.3 on page 70 are
replaced through reproduction. Replacing some forests
may take just a few decades. Others forests take longer.
Plantations (where humans deliberately plant trees for
timber) can be replaced faster than a natural forest.
Replacing animals on farms may take a year or so.
Sa
Some resources like coal and oil take millions of years
to be replaced naturally. So to a human these resources
would seem like they are not being replaced. As such,
they are considered to be non-renewable resources.
Rocks and soils are also considered to be non-renewable
resources because they take so long to be replaced.
pa
A renewable resource is a resource that is replaced
by natural processes that occur in a timescale shorter
than an average human life. This means that renewable
resources take less than eighty or so years to be
replaced. For example, most trees can be regarded as
renewable resources because they grow to maturity in
less than eighty years. The major renewable resources
are air, water, sunlight and living things.
e
The time taken for a resource to be replaced determines
whether it is classified as renewable or non-renewable.
This plant relies on the hummingbird to pollinate
its flowers. To attract the hummingbird the plant
produces a sugary substance called nectar.
Figure
3.1.2
m
pl
Renewable and nonrenewable resources
Discuss with students how different living
things take different amounts of time to
replenish. Animals need time to reproduce.
If too many are culled or used, populations
take a long time to regrow. If only minimal
numbers are killed, populations generally
stay similar. Plantations of forests or crops
can generally be replanted soon after the last
lot has been ploughed or cut down. However
the soil also needs to be replenished.
Farmers know that sometimes crops need to
be rotated or different food sources planted.
s
These resources are not just used by humans to make
things with or to supply us with energy. Almost all life
depends on these resources. Many of these resources
need to be protected by humans to assist in the survival
of all living things, including ourselves.
Earth resources
69
Extension
Not renewable!
MI: Verbal/Linguistic, Interpersonal,
Visual/Spatial
In this activity students will research one of
the non-renewable sources of energy (coal,
oil or gas), what it is used for, and what are
its benefits and disadvantages. Students
will then present their information on a
website aimed at primary school students.
1 In groups, choose one of the nonrenewable sources of energy.
2 Brainstorm what is known about it by
members of the group and come up
with a list of at least five questions to
research.
3 Using the internet and other resources,
research what the energy form is used
for and prepare a PMI (Plus, Minus,
Interesting) table to show results.
4 Present the information in a website
format. Choose appropriate programs to
present the information.
5 As a class, link together the sites that
each group created, for a comprehensive
set of information. Present the
information to some younger students, if
there is an opportunity to do so.
Chapter 3
Earth resources
69
Helpful hint
Air: a renewable resource
Ancient fuels
About 21% of the air (by volume) is oxygen gas. Oxygen
is constantly being used by animals and plants, but is
also constantly being replaced by plants. This allows the
oxygen level of the atmosphere to stay about the same.
Scientists describe the movement of materials from one
place to another and then back again as a ‘cycle’. Oxygen
cycles through Earth and its atmosphere.
MI: Verbal/Linguistic
Most students will know that fossils are
the remains of dead organisms, usually
preserved in rock. Generally, fossils are of
extinct animals due to the amount of time
it takes for fossilisation to occur. The term
fossil means ‘old’ or ‘ancient’, so, as fossils are
old, fossil fuels must be old too! They could
also be called ‘ancient fuels’!
Figure
3.1.3
Extension
Animals
Animals are a renewable resource because they
reproduce.
Air as a resource
MI: Verbal/Linguistic, Visual/Spatial,
Logical/Mathematical
s
Air is a mixture of gases and suspended particles such
as dust, smoke and water droplets. The main gases in
air and their importance to life on Earth can be seen in
Table 3.1.1.
Percentage
in air
N it r o g e n
O x y gen
21
0 .0 3
e
C arbo n
d io x id e
78
0 .9 7
m
pl
O ther gas es
s u ch as
o z o n e, w ater
v ap o u r an d
argo n
Sa
Importance to life
Pro v
to m
chem
an d
a s fo
id e s n
ak e p
ic a l s
o ther
o d.
u t r ie n t s fo r
r o t e in s a n d
, w h ic h h u m
a n im a l s c a n
How it is
used
Adaptations
M a n y u s e s d e p e n d in g o n
t h e g a s . O z o n e s h ie l d s
h u m a n s fr o m u l t r a v io l e t
r a y s ( r e d u c in g o u r r is k o f
s k in c a n c e r s ) . W a t e r v a p o u r
is p a r t o f t h e w a t e r c y c l e
t h a t c a r r ie s w a t e r a r o u n d
t h e p l a n e t . A r g o n is u s e d in
l ig h t g l o b e s .
Air
Soil
Sunlight
Water
Rocks
Living things
70
PEARSON science
7 Teacher Companion
70 PEARSON VFLHQFH
Disadvantages
or problems
Green plants use carbon dioxide, water and
energy from sunlight to make their food by the
process of photosynthesis.
E s s e n t ia l fo r p l a n t s t o
m a k e t h e ir o w n fo o d b y
p h o t o s y n t h e s is .
MI: Logical/Mathematical, Verbal/Linguistic
Resource
Figure
3.1.4
E s s e n t ia l fo r m o s t l iv in g
t h in g s , t o r e l e a s e e n e r g y
fr o m fo o d t h a t t h e ir b o d ie s
can then u s e.
Comparison table or flow chart
Ask students to draw up and complete a
table with the following rows and columns.
p lan t s
o ther
an s
u s e
pa
Gas
ge
Table 3.1.1 Gases in the air
Renewable or nonrenewable uses
Earth’s fragile
atmosphere
SciFile
Ask students to find out about one ‘living
thing’, such as a cow, that is a renewable
resource. In Australia we also eat kangaroo
meat and this could also be a renewable
resource. Students research to find out what
their chosen living thing is used for (e.g.
sheep are used for wool and meat) and how
common it is in Australia.
Summarising
All of the oxygen on Earth is thought to have originally
been produced by microscopic plant-like organisms
and green plants. Green plants like the one in Figure
3.1.4 use the energy from sunlight, carbon dioxide and
water to make their own food. The process is called
photosynthesis. As well as producing the plant’s food,
photosynthesis also produces oxygen.
The atmosphere is the
very thin layer of air
around the Earth’s
surface. The first
astronauts who ventured
into space were amazed
at how thin and fragile
the atmosphere looked
from space. Many said it
made them think very
deeply about the
damage humans are
doing to the atmosphere.
Applying skills
Only about 0.03% of air is carbon dioxide. This is enough
to supply the carbon dioxide needed in photosynthesis.
Animals breathe out carbon dioxide because it is a
waste product of the processes that release energy in
their bodies. So carbon dioxide is also being replaced
in the air. It is part of a cycle, where it goes from the
atmosphere to plants, and then back again from animals
to the air. This cycle of oxygen and carbon dioxide is
shown in Figure 3.1.5.
p lan t u s es car b o n
to m ak e s u gar
m o lecu les
p lan t p r o d u ces
o x y gen
Sunlight: a renewable resource
Graphing gases
Sunlight is a renewable resource and will be for as long
as the Sun keeps shining. The Sun is a star, and will
continue to shine for billions of years.
MI: Visual/Spatial, Logical/Mathematical
Ask students to use the data for the gases in
air to produce a pie chart.
Water as a resource
Teacher demonstration
Water covers most of the Earth’s surface and all living
things (like the bird in Figure 3.1.6) need it. No organism
can live without water for long. For this reason, water is
the Earth’s most important resource.
Gases from the atmosphere
MI: Interpersonal, Visual/Spatial
Liquid nitrogen and oxygen
p l a n t t a k e s in
c a r b o n d io x id e
1 Place items into the liquid nitrogen and
smash them after they have frozen, e.g.
a partially inflated balloon, a banana,
rubber gloves.
s
a n im a l t a k e s
in o x y g e n
Get some liquid nitrogen and perform a
number of demonstrations. Many ideas for
these can be sourced on the internet. The
following are examples.
a n im a l r e l e a s e s
c a r b o n d io x id e
Sunlight as a resource
Sunlight has an essential role in supporting life on Earth.
• Plants use sunlight to produce food.
Water is a renewable resource because it can move from
place to place and replenish an area. It has a cycle.
However, only a tiny fraction of the water on Earth is
made new each day. Some water is made when:
• fossil fuels like petrol and coal burn
The total amount of water on Earth is thought not to
have changed much since the planet formed.
2
p78
Earth resources
1 Test for carbon dioxide using the
limewater test.
Carbon dioxide will turn limewater
cloudy with the calcium carbonate
precipitate in the liquid. Bubble carbon
dioxide through the limewater to see the
reaction.
• living things release energy in their bodies.
Water will be covered in detail in Unit 3.3 and
in Chapter 4.
Carbon dioxide
Limewater test: Limewater (saturated
calcium hydroxide solution) reacts
with carbon dioxide to form a calcium
carbonate precipitate.
• living things like trees burn
PEARSON science
2 Pour some liquid nitrogen into a roundbottom flask held on a retort stand by a
clamp. This will cause liquid oxygen to
form on the outside of the flask and drip
off. The liquid nitrogen is cold enough to
make the oxygen condense into a liquid.
ge
pa
Water: a renewable resource
Sa
• Sunlight warms the Earth’s atmosphere, land and
water, keeping it warm enough for most water to
stay liquid. If the Earth cooled too much, then all
water would freeze and turn to ice. Living organisms
contain a lot of water and so they would also freeze.
Figure
3.1.6
e
Nitrogen gas also has its own cycle as it is absorbed by
some organisms and released by others. Gases such as
oxygen, carbon dioxide and nitrogen can also
move to areas of low concentration where one
1
of them is being used up.
p77
Water is a very
important
resource on Earth
because no living
thing can survive
without water.
Life cannot exist
without water. For this
reason, scientists
searching for signs of
life in space are only
looking at planets and
moons where water
can be detected.
m
pl
Figure
3.1.5
The exchange of oxygen and carbon dioxide
between plants and animals renews these
gases in the atmosphere.
SciFile
Living on other
planets
71
2 Demonstrate how a fire extinguisher
works by pouring carbon dioxide over a
candle in a beaker.
Fire extinguishers use nitrogen or
compressed carbon dioxide that is
released when needed to put out fires.
Pouring carbon dioxide directly on a
lit candle should demonstrate how the
candle is put out by the extinguisher.
7 RESOURCES
Practical activities
Prac 1, page 77, looks at renewing
air.
Prac 2, page 78, investigates the
water-holding capacity of soil.
Skills support
Science and Inquiry 1 has
additional support for Recording
and processing data—graphs.
Skill 2.11
Chapter 3
Earth resources
71
Questioning
Table 3.1.2 Minerals and their uses
Rocks as a resource
Where are rocks used?
MI: Verbal/Linguistic
Rocks provide two different resources:
Mineral
Main use
• the rocks themselves
B a u x it e
Where have you seen complete rocks used
(i.e. not materials, but rocks themselves)?
The text mentions how limestone and
sandstone are easy to cut. Use the following
clues to get students to think of where rocks
are used (and in doing so differentiate
between rocks and minerals).
• materials found in rocks.
C o n t a in s a l u m in iu m . A l u m in iu m is u s e d fo r
m a k in g a ir c r a ft , d r in k c a n s a n d h ig h v o l t a g e
p o w e r l in e s .
H a e m a t it e
C o n t a in s ir o n . Ir o n is u s e d t o m a k e s t e e l ,
w h ic h is u s e d in c a r b o d ie s , n a il s , s h ip s
a n d b r id g e s .
M a l a c h it e
C o n t a in s c o p p e r . C o p p e r is u s e d in
e l e c t r ic a l w ir in g .
H a l it e
C o n t a in s s o d iu m c h l o r id e ( t a b l e s a l t ) . S o d iu m
c h l o r id e is u s e d in fo o d p r e p a r a t io n a n d
m e d ic a l a p p l ic a t io n s .
•
In fancy buildings this rock is often used
for building and moulding. It is easy to
mould as it is soft and quite sandy.
Sandstone
•
There are many different types of rock. Some rocks are
hard and can be used without altering them or removing
any materials from them. These solid rocks are used
mainly for roads and buildings, like the one shown in
Figure 3.1.7. Other rocks are soft, like limestone and
sandstone. These rocks are easy to cut, so they are used
in paving and walls. Many of
the founding buildings
of cities are often
built from the
local bedrock.
Figure
3.1.7
This rock is often used in kitchen
benchtops.
s
Extension
ge
Rocks are made from substances called minerals.
Minerals differ in their physical properties such as
colour and hardness. You can see how minerals appear
in a magnified view of a rock in Figure 3.1.8. Many
minerals are important resources for humans. A variety
of minerals and their uses are shown in Table 3.1.2.
Other minerals in rocks
pa
MI: Verbal/Linguistic, Visual/Spatial,
Bodily/Kinaesthetic
Catering for diversity
of learners
Sa
Minerals in the body
MI: Bodily/Kinaesthetic, Verbal/Linguistic,
Visual/Spatial, Interpersonal
Ask students to research minerals needed
by the human body. Compile a table with
headings of ‘Minerals in the body’, ‘What
they are used for’ and ‘Where we get them’.
7 RESOURCES
Pearson Reader
Interactive activity: Rock
formation
This interactive activity summarises
the different types of rocks, how they are
formed and their uses. It is available as a
whiteboard activity and as a self-contained
interactive activity.
72
PEARSON science
7 Teacher Companion
Most of the rocks of the Earth were formed millions
of years ago. However, in a few places, rocks are still
forming today. Some rocks form when hot liquid from
inside the Earth cools either below or above the ground.
This type of rock is called igneous rock. Volcanoes (like
the one in Figure 3.1.9) are places where igneous rocks
form. The igneous rocks that form below ground can
take thousands to millions of years to form. Igneous
rocks form on the surface in a day or so because the
liquid rock (lava) cools quickly in the air.
m
pl
In groups have students investigate other
minerals and any uses they have. Create a
complete table of the information found by
each student and that provided in the text.
Rocks: a non-renewable resource
e
There are a number of other common
minerals in rocks that are not listed in
Table 3.1.2.
PEARSON science
Rocks also contain resources that are not minerals.
Water is often found in rocks. The fossil fuels oil, natural
gas and coal are energy sources that are found in or
between layers of rock deep below the ground.
Stone buildings
are built from
rocks.
Granite, limestone, marble
Rocks contain some of the minerals that are needed by
living things. As the rocks gradually break down, they
release minerals which end up in the water of oceans
and lakes, and in the soil. From the water and soil, the
minerals are taken up by plants and animals, providing
them with necessary trace elements.
Figure
3.1.8
This is a magnified view of a rock showing that
it is composed of different minerals. Each
different colour is a different mineral.
72 PEARSON VFLHQFH
Figure
3.1.9
Although new rocks form in and around
volcanoes every day, they cannot be considered
a renewable resource because the overall
process takes so long.
A poem
Other types of rocks form when sediments stick together
and harden to become rock. This type of rock is called
sedimentary rock. Most sedimentary rocks form over
many thousands or millions of years.
MI: Verbal/Linguistic, Musical/Rhythmic
Get students to read the unit and then use
their knowledge of earth resources to write
a poem using the key words shown in bold
throughout the unit. These words are also
listed in the vocabulary preview.
Only a tiny fraction of the Earth’s rocks is being replaced
each year. The replacement takes so long that rocks are
not considered to be renewable resources. Therefore
the minerals in the rocks are non-renewable resources.
Oil and coal are materials that are found in or between
rock layers, and are also non-renewable resources. Oil
and coal were formed from dead plants and animals
that lived many millions of years ago and are not being
formed today.
Extension
Soil as a resource
MI: Verbal/Linguistic, Visual/Spatial, Bodily/
Kinaesthetic, Interpersonal
Soil as a resource
Rock can be worn away by the processes of weathering
and erosion. These natural processes have been wearing
away rocks throughout the Earth’s history.
Weathering
Weathering
g is the process of breaking rocks down into
smaller pieces. Weathering happens in the following ways:
• Running water and waves can gradually wear away
rocks.
• Strong winds blast rocks with small rock particles that
wear the rocks away.
• Natural chemicals in the air, soil and water attack
substances in the rock. The rock then crumbles and
s
sediments by the process of
weathering. Sediments can build up around the parent
rock or can be carried away by water, wind and ice in a
process called erosion. Water, wind and ice are referred
to as agents of erosion.
The sediments that are carried away from weathered
rock by water, wind or ice are eventually dropped
somewhere. You can see this in Figure 3.1.11 on page 74.
The process where sediments drop out of a moving
stream of water, wind or ice
is called deposition.
Earth resources
Extra information
Australian sinkholes
There is a tourist spot in South Australia
that is commonly known as The Sunken
Garden. It formed in the 1800s when the roof
of a limestone cave dissolved. It is now a
tourist spot with viewing chairs and a special
garden. Go to the weblink on Pearson Reader
to see photos.
m
pl
Sa
SciFile
Sink holes
Sink holes can appear
suddenly in areas
where limestone is
the common type of
rock. Sink holes are
formed when the
limestone below the
surface is weathered
by chemical action
and caves form and
then collapse. This
sink hole appeared in
2010, in Guatemala,
South America, right
next to someone’s
home!
Erosion and deposition
e
may form a cave like the one shown in Figure 3.1.10.
This limestone cave was formed by the action
of rainwater containing acid that attacked the
limestone rocks over a long time.
ge
• Water settles in cracks in rocks. As water freezes into
ice it expands (gets larger), widening the crack even
more.
Figure
3.1.10
pa
• Changes in temperature between day and night or
because of weather and the seasons, can split rocks.
Have students collect some soil and turn it
into a display project. On the soil bucket (or
pot) attach images and information about
what this soil is useful for. It may be worth
typing it up and then gluing it on. Imagine
students are preparing this for display for
parents to explain why soil is important.
Students can use internet or book resources
to find images and information about
how soil is useful. They could extend this
by growing something in the soil if time
permits.
73
PEARSON science
7 RESOURCES
Pearson Reader
Weblinks
Link to ‘The Sunken Garden’ for
photos.
Chapter 3
Earth resources
73
In the dirt
science
Background
Soil contains a range of nutrients and
materials that vary depending on what the soil
has come from (i.e. what rocks and minerals
are nearby, how it has been made or formed,
what weathering and erosion has occurred
to leave this soil in that spot). Some soil will
also contain larger materials such as leaves,
sticks, (that may eventually decompose to
become part of the soil) and other soil will be
more pure.
In the dirt
Collect this …
This sandstorm approaching the Saudi Arabian
Figure
capital Riyadh shows how much erosion and
3.1.11
deposition the wind can cause.
• fine rock particles (sediments)
MI: Bodily/Kinaesthetic, Visual/Spatial,
Verbal/Linguistic, Logical/Mathematical,
Interpersonal, Intrapersonal
Have students visit their local plant nursery
to investigate the different fertilisers
available. They should find out why there
are different types of fertilisers and how
they differ. Fertilisers will differ according
to their ratios of nitrogen, phosphorus
and potassium (NPK). They may also vary
according to method of distribution; that is,
they may be used as liquids, pellets, powders
or premixed with organic matter.
Students could conduct an experiment
to find the most effective fertiliser for a
particular plant, or, alternatively, the most
appropriate plant for a particular fertiliser.
Such an investigation may require a
significant amount of time.
PEARSON science
7 Teacher Companion
ic r o s c o p e a t a b o u t 4 0 m a g n ific a t io n
a h a n d l e n s . Is t h e m a t e r ia l in t h e s o il a l l
e o r is it m a d e o f d iffe r e n t m a t e r ia l s ?
o r k o u t w h a t t h in g s a r e in t h is s o il .
S t u d y t h e o t h e r s o il s t o s e e if t h e y h a v e t h e
s a m e m a t e r ia l s in t h e m .
s
Describe w h a t y o u s a w .
• dissolved minerals and gases.
You can see these in Figure 3.1.12.
n em ato de
w o rm
d e c a y in g l e a f
(hu m u s )
r o c k p a r t ic l e s
w ater betw een
r o c k p a r t ic l e s
Figure
3.1.12
a ir s p a c e
Soil consists of many components which can
support the growth of plants and animals.
74 PEARSON VFLHQFH
Explain w h y s o m e s a m p l e s w e r e s im il a r w h il e
o t h e r s w e r e d iffe r e n t .
earthw o rm
pa
m
pl
Sa
Homework
74
s tereo m
o r w it h
the s am
Tr y t o w
Record this …
• water
p lan t r o o t
Learning strategies
Wear gloves and
do not inhale dust.
Do this …
1 S t u d y o n e o f t h e s o il s a m p l e s w it h a
2
e
Students will hopefully be able to find
examples of different materials and minerals
in the soil. Some of this will not be particularly
obvious, as grains could be quite small. Ask
students to reflect on this activity when looking
at soil as a resource throughout this unit.
SAFETY
• humus (decaying wastes and dead organisms)
Possible results and looking forward
NPK fertilisers
s t e r e o m ic r o s c o p e o r
han d len s
s a m p l e s o f d iffe r e n t
s o il s
• living organisms (such as worms and moss)
ge
Give students a range of soils—perhaps even
some potting mix—to compare with average
soil from the school yard. What is different
between these soils? What does this mean
with respect to manufactured or processed
soil?
5V
W h a t is in s o il ?
on, making new soil in the process. Soils are composed
of:
Hints and suggestions
fun
Soil profiles
different layers (as shown in Figure 3.1.13). These layers
are called horizons and together the horizons make up
the soil profile. The top layer (A horizon) is often a dark
brown or black colour due to the high humus content
from the organic matter it contains. Most plant roots
are found in this top layer of soil. This horizon provides
nutrients needed for plant growth. The next layer
(B horizon) is called the subsoil. The subsoil is usually
more compacted, contains less air and less humus and
is therefore lighter in colour. The third layer (C horizon)
is broken bedrock. At the bottom is unaltered rock.
Horizons B and C usually have little impact on plant
growth.
Extension
d e c a y in g v e g e t a t iio n
A h o r iz o n
B h o r iz o n
C h o r iz o n
However, in most places on Earth, soils are not being
renewed. If a farmer’s soil blows away in the wind (or
a tornado like the one in Figure 3.1.14) or is washed
away in floods, then it is not likely to be replaced in the
farmer’s lifetime. Some soils form in places where the
rocks on the Earth’s surface are weathered. However, this
process takes hundreds or thousands of years to form
soil only a few centimetres thick. Therefore most soils
are not considered to be a renewable resource.
Fertilisers
MI: Verbal/Linguistic, Visual/Spatial
Ask students to research different types and
different brands of chemical and natural
fertilisers available in the market. Students
can work in groups and should include
at least 6 different fertilisers to compare
(including the common fertilisers listed on
page 75).
u n alt er ed
bedro ck
Figure
3.1.13
Students present the information as a table
with images for each as appropriate and
include the following in the table:
A soil profile shows that soil has clear layers
which are revealed as you dig down.
Name of fertiliser, type (chemical or natural),
how it is manufactured, advantages,
disadvantages, other comments.
Fertilisers
Fertilisers are materials that supply mineral nutrients
to plants. They contain substances like phosphorus and
nitrogen, which plants need to live. Farmers often add
them to the soil to improve crop growth.
s
Assessment
Common fertilisers are:
Evaluate understanding
ge
• untreated animal droppings such as manure from
sheep or chickens
Resources
• ‘blood and bone’. This is the dried and cooked
remains of meat and bone from abattoirs
MI: Verbal/Linguistic
pa
• chemical fertilisers. Many are manufactured from
animal droppings. For example, bird droppings can
be processed into a fertiliser called superphosphate.
3
3..1
1
Reteach relearn
MI: Interpersonal, Logical/Mathematical
Revise with students the different resources
covered in this unit. Then ask them to rank
them in order of priority highest to lowest.
Obviously this is relative, and all resources
are needed in some extent. However, the
activity should help them appreciate the
benefits of all.
3..2
2
p79
Earth resources
To assess students’ knowledge of resources,
ask them to give examples of each resource.
The best resource
A tornado is a rapidly spinning column of air
that forms during certain weather conditions.
Tornadoes can strip topsoil from the ground and
make it very difficult for any crops to grow.
Figure
3.1.14
Sa
In some places the rock particles carried by water, wind
and ice can build up quickly. An example is where many
rivers carrying sediments meet in one place called
a river flood plain. In this way the soil is continually
added to. Soil can also be enriched by humans in home
gardens or on farms. Adding fertilisers or mulch (rotting
leaves, bark and twigs) adds nutrients to the soil.
m
pl
Soil: a non-renewable resource
e
There is evidence that excessive use of chemical
fertilisers is damaging soils and streams and rivers. For
this reason, some farmers are reducing their use and are
using natural fertilisers instead.
75
Alternative assessment
I have learnt …
PEARSON science
7 RESOURCES
Practical activity
Prac 3, page 79, investigates
erosion and weathering.
Activity Book
3.1 Differences in soils
MI: Verbal/Linguistic
3.2 Looking after soils
MI: Logical/Mathematical
MI: Interpersonal
As all students will have started this unit with
different levels of background knowledge, it
may be interesting for them to think about
what they have gained personally. Ask
students to write a series of ‘I have learned’
sentences. They could then share their
sentences with the class and add to their own
if another student has considered something
they hadn’t.
Chapter 3
Earth resources
75