8E In the drink - WikispacesTEACHER... · 8E In the drink This unit uses the context of safe water supplies to introduce ... Apply and use the particle model to describe a range of

8E

Exploring Science edition © Pearson Education Limited 2008134

In the drink8E

This unit uses the context of safe water supplies to introduce and develop the idea that many everyday substances are actually mixtures and that these mixtures can be separated, using a variety of techniques, to produce useful materials.

We recommend between 7.5 to 9 hours teaching time for this unit.

From KS2 previous units most pupils will:• be able to explain why undissolved solids can be separated from

a mixture by fi ltering• know that solids remain in the solution when they dissolve• know that a dissolved solid can be recovered by evaporation.

This unit builds on ideas introduced in the QCA Scheme of Work for KS2: Unit 4D Solids, liquids and how they can be separated, Unit 5C Gases around us, Unit 5D Changing state, Unit 6C More about dissolving and Unit 6D Reversible and irreversible changes.

The unit considers ideas about mixtures in terms of different mixtures that pupils should fi nd familiar, in order to show the range of mixtures present in the world.

• Topic 7Ha introduces the idea that the water we get from our taps has to be treated to make it clean, and then revisits mixtures and dissolving, which pupils will have met in KS2. Could level work looks at how our drinking water is treated.

• Topic 7Hb looks at the particle model of matter to explain dissolving, fi ltering and the conservation of mass, and then looks at saturated solutions, and the effect of temperature on solubility. There is an optional Investigation Attainment Target 1 on the effects of temperature on solubility. A set of level descriptions is provided in the ASP. Could level work on the solubility of gases is provided.

• Topic 7Hc focuses on the evaporation of water from solutions and the process used to do this in the laboratory, and also how this is applied to the production of salt from brine. Could level work is provided on Gandhi and the Salt Act.

• Topic 7Hd focuses on chromatography and its applications. Could level work looks at DNA ‘fi ngerprinting’.

• Topic 7He looks at distillation, including an explanation of why it works in terms of particles. Could level work is provided on water supplies and desalination, and on fractional distillation. The unit fi nishes with a discussion of whether and how we should conserve water supplies in the UK.

ExpectationsKey concepts At the end of this unit…

All pupils must:(WTL4) Recognise that we need safe drinking water.(L4) State that water is treated before being supplied to homes.

Most pupils should:(L5) Use the particle model to describe what happens when something dissolves.(L6) Use the particle model to explain why mass is conserved when something dissolves.

Some pupils could:(L7) Describe some of the human and environmental effects of supplying large quantities of water.(L7) Use particle models to explain how mixtures are separated by distillation.(L8) Explain how the challenges of supplying and conserving water are overcome when demand increases.

Key processes At the end of this unit…

All pupils must:(WTL4) Measure temperature and mass.(WTL4) Use heating equipment safely.(L4) Identify patterns in data.(L4) Carry out fi ltering and chromatography safely in the laboratory.(L5) Describe how to obtain salt from rock salt.

Most pupils should:(L5) Describe how to separate simple mixtures using fi ltration and chromatography.(L5) Present data from investigations as line graphs.(L5) Carry out evaporation and distillation safely in the laboratory.(L5) Explain what a chromatogram shows.

Some pupils could:(L6) Point out patterns in their data using a line graph.(L6) Use patterns in data to make predictions.(L7) Evaluate experimental methods, explaining their strengths and weaknesses.

Range and contentAt the end of this unit…

All pupils must:(WTL4) Recall that mixtures can be separated.(L4) Recall some ways of conserving water supplies.(L4) Recall some examples of the uses of different separating techniques.(L5) Describe what happens in dissolving in terms of particles.(L5) Explain what a saturated solution is. (L5) Recall that solutes that are insoluble in water may dissolve in other solvents.

Most pupils should:(L6) Describe how salt can be obtained from mines.(L6) Describe some of the ways in which water is treated before being piped to our homes.

Some pupils could:(L7) Describe how solubility increases with increasing temperature for most solutes.(L8) Explain how fractional distillation works.(L8) Describe how the solubility of gases changes with temperature.

For a list of updated and vetted websites that can be used to support your teaching of this unit please visit the Exploring Science: How Science Works E-Forum (http://groups.google.co.uk/group/exploringscience.

M05_TTPG_5453_U04_5p.indd 134 12/9/08 12:47:11

© Pearson Education Limited 2008 135Exploring Science edition

8E

In the drink 8E

8E NC statements coveredFrom KS2

Statement TopicSc3 2a To describe changes that occur when

materials are mixed.8Ea, 8Eb

Sc3 2d About reversible changes, including dissolving, melting, boiling, condensing, freezing and evaporating.

8Ea, 8Eb, 8Ec, 8Ee

Sc3 3a How to separate solid particles of different sizes by sieving.

8Ea

Sc3 3b That some solids dissolve in water to give solutions, but some do not.

8Ea

Sc3 3c How to separate insoluble solids from liquids by fi ltering.

8Ea

Sc3 3d How to recover dissolved solids by evaporating the liquid from the solution.

8Ec

Sc3 3e To use knowledge of solids, liquids and gases to decide how mixtures might be separated.

All

At KS31 Key concepts

Statement Topic1a Using scientifi c ideas and models to explain

phenomena and developing them creatively to generate and test theories.

8Ea, 8Eb, 8Ec

2a Exploring how the creative application of scientifi c ideas can bring about technological developments and consequent changes in the way people think and behave.

8Ed, 8Ee

2b Examining the ethical and moral implications of using and applying science.

8Ee

2 Key processes

Statement Topic1a Use a range of scientifi c methods and techniques

to develop and test ideas and explanations.all

1b Assess risk and work safely in the laboratory, fi eld and workplace.

8Ea, 8Eb, 8Ec, 8Ee

1c Plan and carry out practical and investigative activities, both individually and in groups.

all

2a Obtain, record and analyse data from a wide range of primary and secondary sources, including ICT sources, and use their fi ndings to provide evidence for scientifi c explanations.

8Ea, 8Eb, 8Ec, 8Ed

2b Evaluate scientifi c evidence and working methods.

8Ea, 8Eb, 8Ec, 8Ed

3a Use appropriate methods, including ICT, to communicate scientifi c information and contribute to presentations and discussions about scientifi c issues.

8Eb, 8Ec, 8Ee

3 Range and content

Statement Topic2a The particle model provides explanations for the

different physical properties and behaviour of matter.

all

4c Human activity and natural processes can lead to changes in the environment.

8Ee

4 Curriculum opportunities

Statement Topica Research, experiment, discuss and develop

arguments.8Ea

c Use real-life examples as a basis for fi nding out about science.

all

d Study science in local, national and global contexts, and appreciate the connections between these.

8Ea, 8Ee

e Experience science outside the school environment, including in the workplace, where possible.

8Ee

g Recognise the importance of sustainability in scientifi c and technological developments.

8Ea, 8Ee

h Explore contemporary and historical scientifi c developments and how they have been communicated.

8Ed

j Consider how knowledge and understanding of science informs personal and collective decisions including those on substance abuse and sexual health.

8Ea, 8Ee

Links with other units

7G Particle theory. 9B Importance of mineral salts to humans.

8A Importance of mineral salts to humans.

9D Importance of mineral salts to plants.

Cross-curricular links

Topic Links8Ec History – Gandhi and the Salt Act8Ee Geography – water (hydrological) cycle

Skills opportunities for Personal, Learning and Thinking Skills (PLTS), literacy, numeracy and ICT are included in the individual topic notes.

M05_TTPG_5453_U04_5p.indd 135 12/9/08 12:47:12


8E

Framework statements covered by Unit 8E

1 How Science Works

1.1 Explanations, arguments and decisions

Code Framework threads Year 8 Topic1.1b Applications, implications and

cultural understandingRecognise that decisions about the use and application of science and technology are infl uenced by society and individuals, and how these could impact on people and the environment.

8Ee

1.1c Communication for audience and with purpose

Use a range of scientifi c vocabulary and terminology consistently in discussions and written work.

all

Adapt the stylistic conventions of a range of genres for different audiences and purposes in scientifi c writing.

8Ea, 8Ee

1.2 Practical and enquiry skills

Code Framework threads Year 8 Topic1.2a Using investigative approaches:

planning an approachDescribe an appropriate approach to answer a scientifi c question using sources of evidence and, where appropriate, making relevant observations or measurements using appropriate apparatus.

8Ea, 8Eb, 8Ec, 8Ee

1.2b Using investigative approaches: selecting and managing variables

Describe and identify key variables in an investigation and assign appropriate values to these.

8Eb, 8Ec

1.2c Using investigative approaches: assessing risk and working safely

Explain how to take action to control the risks to themselves and others, and demonstrate competence in their practical technique.

8Eb, 8Ec

1.2d Using investigative approaches: obtaining and presenting primary evidence

Explain how the observation and recording methods are appropriate to the task.

8Ea, 8Eb, 8Ec

Describe ways in which the presentation of experimental results through the routine use of tables, charts and line graphs makes it easier to see patterns and trends.

8Ea, 8Eb, 8Ec

1.2e Working critically with primary evidence

Describe how the patterns and trends in the results link to the conclusions drawn and whether the evidence is suffi cient.

8Eb, 8Ec, 8Ed

Describe and suggest, with reasons, how planning and implementation could be improved.

8Ea, 8Eb, 8Ec

1.2f Working critically with secondary evidence

Describe what needs to be considered in the collection and manipulation of simple secondary evidence to evaluate the conclusion or interpretation made.

8Eb

3 Chemicals and material behaviour

Code Framework threads Year 8 Topic3.1 Particle models Apply and use the particle model to describe a range of physical observations. 8Eb, 8Ec

Apply and use the particle model to describe a range of separation techniques. all3.2 Chemical reactions Recognise that materials can be made up of one or more kinds of particles. 8Ea

5 The environment, Earth and the Universe

Code Framework threads Year 8 Topic5.1 Changing environment and

sustainabilityRecognise simple ideas of sustainable development. 8Ee

8E In the drink

M05_TTPG_5453_U04_5p.indd 136 12/9/08 12:47:12


In the drink 8E

8E

8E R

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how

to

fi lte

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ture

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ids

from

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ply

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acti

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ll th

at t

here

are

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ids

that

can

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used

as

solv

ents

; exp

lain

why

we

cann

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rink

sea

wat

er.

diss

olve

, fi lt

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g, in

solu

ble,

mix

ture

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aque

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uble

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ute,

sol

utio

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ent

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lain

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1–2,

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an o

ther

s; r

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w

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3, E

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lain

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ould

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ome

of th

e w

ays

in w

hich

our

wat

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trea

ted

befo

re it

is s

uppl

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to h

omes

; de

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e di

ffere

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ixtu

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of s

olid

s, li

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gas

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ter

1&3,

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48E

bM

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All

pu

pils

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st:

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ain

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a d

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; exp

lain

how

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ake

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l tha

t the

re is

a li

mit

to th

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ount

of s

olid

that

will

dis

solv

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wat

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and

use

a gr

aph

to fi

nd o

ut h

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is v

arie

s w

ith te

mpe

ratu

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Star

ter

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Shou

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ost

pu

pils

sh

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plai

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hy t

he m

ass

of a

sol

utio

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the

sum

of

the

mas

ses

of t

he s

olut

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eas

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he li

mit

of s

olub

ility

will

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diffe

rent

for

diffe

rent

sol

utes

; rec

all t

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or m

ost s

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ore

solid

will

dis

solv

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hen

the

wat

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hot

ter.

satu

rate

d, s

olub

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Star

ter

1–2,

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lain

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xplo

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2,

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Cou

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me

pupi

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ould

: rec

all t

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ll so

lids

diss

olve

to s

ome

exte

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le to

use

a q

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ases

dis

solv

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wat

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nd th

at th

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mpe

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38E

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pu

pils

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st:

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at w

ater

usu

ally

con

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s di

ssol

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chem

ical

s; e

xpla

in th

at a

dis

solv

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olid

can

be

obt

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liqu

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car

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vapo

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call

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sal

t can

be

obta

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from

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wat

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atio

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sal

t min

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expl

ain

how

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Act.

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38E

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st:

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atog

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lena

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me

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ter

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eM

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All

pu

pils

mu

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desc

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wha

t ‘pu

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ater

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t dis

tilla

tion

can

be u

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to s

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in it

; exp

lain

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dis

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Shou

ldM

ost

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ould

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abl

e to

exp

lain

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tion

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eas

abou

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rtic

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still

Star

ter

1–2,

Exp

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lain

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ld:

reca

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me

of th

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man

and

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cts

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antit

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wat

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des

wat

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som

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ount

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lain

tha

t fra

ctio

nal

dist

illat

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ecau

se e

ach

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t a d

iffer

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3

M05_TTPG_5453_U04_5p.indd 137 12/9/08 12:47:12


8E In the drink

8E

8E Background Information8Ea – Using water/The solution is clearDissolving is a topic that is superfi cially very simple, but can actually lead to some very complex ideas. One of the key ideas to be brought out is that true dissolving will only occur when the solute is broken down into particles that are too small to be seen with the naked eye. A common error will be to assume that any form of dispersion is evidence of dissolving – the fact that ‘soluble’ aspirins are often in fact only partially soluble may be a source of this misunderstanding. These mixtures are suspensions (though this word is not used in the Pupil’s Book).

Suspended substances may fall to the bottom of the liquid on standing, or they may, if the particles are small enough, remain suspended virtually indefi nitely. In this case you get a colloidal suspension, such as an emulsion, gel or aerosol. This is dealt with on Worksheet 8Ea(7).

Another common error is the confusion between the meanings of the words ‘clear’ and ‘colourless’. The use of ‘clear’ as a description of colourless glass bottles at the bottle bank will not help. In the Pupil’s Book the word clear is used to mean transparent, with the colour of the liquid being an independent description. A full description of the liquid will therefore involve a minimum of two words (e.g. clear blue, misty yellow, clear and colourless). It may also be worth stressing to some pupils the difference between ‘colourless’ and ‘white’, perhaps by showing them a test tube full of water and one containing milk.

Some common models based on solute particles fi lling up ‘gaps’ in the liquid have come under critical scrutiny in recent years. At best, they are a gross oversimplifi cation of the actual particle interactions. Particles in a liquid are closely packed, hence the diffi culty in compressing a liquid into a smaller volume. These models usually overstate the size of any gaps and/or distort the relative sizes of solvent and solute particles (sugar molecules, for example, are signifi cantly larger than water molecules).

Mixtures are collections of items or substances that have been brought together by some physical means and that can be separated so that each of the constituent parts is obtained. This process of separation will form the thread through the remainder of this unit, but in every case the method required to separate a mixture is a physical one – no chemical reactions are involved and no new chemicals are formed.

Filtering is a way of sorting items by size – sieving is an example that pupils should be familiar with from KS2 work. Filter papers act in a similar fashion, allowing only tiny particles through and trapping the rest.

Filtering will only separate insoluble solids (which do not dissolve) from the liquid or solvent in which they are found, as dissolved particles are small enough to pass through the paper. In a water treatment plant, fi ltration can only be used to separate the ‘lumps’ from dirty water – fl oating branches, paper waste, solid human waste and particles of soil or dirt. Filtration will not remove the bacteria that live in the water (as they are too small) and it will not remove minerals that are dissolved in it.

8Eb – SolubilityTechnically, solubility refers to the amount of solute that will dissolve in a particular mass or volume of solvent. In this topic, the only solvent used is water, and the overwhelming majority of data available will relate to aqueous solutions. There are potentially a large number of possible combinations of mass and volume units in which solubility can be expressed, and the resulting values will be concentrations, typically expressed in grams of solute per 100 g water, or as moles of solute per cubic decimetre (i.e. one litre) of solution. This latter treatment is clearly well beyond the scope of

a KS3 course. Note also the subtle difference between specifying the volume or mass of solvent and the volume or mass of the fi nal solution.

8Ec – Salt of the EarthEvaporation is a way of extracting dissolved solids from a liquid. If a sample of pure water is evaporated, no solid residue will be left behind, but if a solution (water containing a dissolved solid, or mixture of solids) is heated the water will evaporate leaving the solids behind.

Evaporation of solutions in the laboratory needs care. The solution should be heated until a little remains so that the solid can be formed as the heat stored in the watch glass or evaporating basin evaporates this remaining amount. This will help to stop the solid residue from ‘spitting’ at the pupils and also limit the number of breakages. This process is known as ‘heating to dryness’. If the solid is heated beyond this point, it may ‘jump’ out of the container and may also be changed by the heat.

Copper sulphate is ideal for demonstrating evaporation as its blue colour means that it can be easily seen. Also, the effect of heating it too strongly is a very clear change in colour – anhydrous copper sulphate is produced, which is white if too much water (the water of crystallisation) is removed. The blue colour returns if a little water is added to the white crystals.

Hard water is water with a high mineral content, mostly high levels of magnesium or calcium carbonates, bicarbonates and/or sulphates. Some of the salts in hard water precipitate on heating to form scale which blocks up central heating pipes and furs kettle elements. Soap initially reacts with the hardness salts to form a scum, and no lather is formed until all these salts have reacted. Detergents contain different salts, which form soluble compounds with the hardness salts, and so do not leave scum.

Drinking water standards in the UK are set by UK and EU legislation. The standards set maximum values for concentrations of various ions, organic molecules, specifi ed microbes, compounds such as pesticides, and radioactivity. Sampling is carried out where water leaves the supply points, and also at consumers’ taps.

8Ed – What’s in a solution?Chromatography is a way of separating different chemicals in a liquid. The chemicals must be soluble in the liquid being used. At school level, chromatography is typically used to separate coloured compounds such as dyes in ink or food colouring. At higher levels the compounds being separated are not necessarily coloured – the chromatogram can be treated to make the separate chemicals visible.

Different soluble chemicals form different-sized particles – the smaller the particle the more easily it can move during chromatography. As the solvent soaks up the paper, the different chemicals in the sample move at different speeds, resulting in a spread-out series of ‘spots’. If two samples on the chromatogram contain the same chemical, that chemical will move up the same distance from the start point as the chromatogram is made.

Most dyes, pigments, paints, and so on, are mixed from a selection of pure chemicals. Different manufacturers of paints/dyes use different combinations of chemicals to achieve the desired colour. This fact is made use of when chromatography is used in police work: a sample of paint can be compared with standard samples from different manufacturers to determine its origin.

8Ee Still water/Focus on: Supplying water/Running out …Distillation is a process used to separate a liquid from a mixture of either a liquid and a dissolved solid or several liquids, so that the liquid is not lost.

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In the drink 8E

8E

Simple distillation involves separating a liquid from dissolved solids. The method is effectively the same as evaporation, except that the vapour is collected and condensed to form a liquid.

When using a Liebig condenser in distillation, ensure that the cooling water goes in at the bottom and out at the top. This ensures that the cooling jacket remains full of water. When demonstrating the Liebig condenser to pupils it is worth setting it up the wrong way round to show them that if water is fed in at the top it just runs down the lower surface and does not remain in contact with the central tube.

When heating liquids in a fl ask, anti-bumping granules must be used. These help small bubbles of gas to form as the liquid boils. In the absence of anti-bumping granules, large bubbles of steam can form and shake the fl ask.

Fractional distillation involves the separation of two or more liquids with different boiling points. If the mixture is heated so that one of the liquids boils, this liquid will turn into a gas and leave the boiling fl ask. If this gas is then channelled so that it can no longer return to the hot fl ask, it can be cooled. As a result, it will condense and turn back into a liquid, which can then be collected. If the original mixture contained several different liquids, the mixture can be heated further until the next liquid boils. The gas produced can then be condensed and collected in a different container. This process of collecting different liquids from the same mixture is known as fractional distillation and is used to separate the different chemicals found in crude oil into fractions. Note that pure liquids are not formed during fractional distillation because liquids will evaporate when heated, whether or not they are boiling. So when the mixture in the fl ask reaches the boiling point of one liquid, other liquids in the mixture will also be evaporating to some extent.

Desalination can be carried out by evaporating sea water and then condensing the vapour, but this is energy-intensive. Reverse osmosis forces water through a semipermeable membrane at high pressure. Only water molecules, or other molecules of similar size, can pass through the membrane.

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Pupil’s materials

Number and title Level Location Type Tasks

Using water All PB p63 Classwork Exploring 1

The solution is clear Must PB pp64–65 Classwork Explaining 1

8E Quick Quiz Must/Should ASP Classwork Starter 4

8E Quick Quiz Answer Sheet Must/Should ASP Classwork Starter 4

8Ea Quick Check Must/Should ASP Classwork Plenary 1

8Ea Word Sheet Must ASP Classwork

8Ea(1) The solution is clear Must CHAP Access Explaining 1

8Ea(2) Operation survival 1 Must CHAP Practical Exploring 2

8Ea(3) Operation survival 2 Should CHAP Practical Exploring 2

8Ea(4) A soluble puzzle Must CHAP Homework Homework 1

8Ea(5) Filtering Must/Should CHAP Homework Homework 2

8Ea(6) Water for life Should CHAP Homework Homework 3

8Ea(7) Treating our water Could CHAP Homework Homework 4

Learning objectivesAll pupils must:

(1) explain what a mixture is and what a solution is(2) describe how to fi lter a mixture(3) explain why fi ltering works and why it cannot separate

soluble solids from a liquid(4) apply their knowledge of fi ltering for a practical purpose(5) recall that there are a number of liquids that can be used as

solvents(6) explain why we cannot drink sea water.

Correctly use the words dissolve, fi ltering, insoluble, mixture, opaque, soluble, solute, solution, solvent, transparent.

Most pupils should:(7) appreciate that some mixtures are easier to separate than

others(8) recall that solutes which are insoluble in water may dissolve

in other solvents.Correctly use the words fi ltrate, residue.

Some pupils could:(9) recall some of the ways in which our water is treated before

it is supplied to homes (10) describe different mixtures of solids, liquids or gases.

Topic notes• Targets for the topic can be accessed via the ActiveBook or

ActiveTeach from the link next to the initiator question.• Pupils should have covered solutions and dissolving at Key Stage

2, but will not have been introduced to all the key words in this topic.

Be prepared: 8Ea Starter 1: cafetiere or coffee fi lter.Exploring 2: moss or grass.

Exemplar topic plans

MUST

PB pages 63–65

Starter 1Exploring 1Exploring 3Explaining 1Explaining 2Plenary 3Homework 1

SHOULD

PB pages 63–65

Starter 1Starter 3Exploring 1Exploring 3Explaining 1Explaining 2Plenary 2Homework 3

COULD

PB pages 63–65

Starter 1Starter 3Exploring 1Exploring 3Explaining 1Explaining 2Explaining 3Plenary 1Homework 4

SHOULD 2 Yr KS3*

PB pages 64–67

8Ea Starter 18Ea Explaining 18Eb Explaining 18Eb Exploring 28Eb Plenary 28Eb Homework 2

*This table is repeated in 8Eb.

Using water8Ea

8Ea

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Using water 8Ea

8Ea

Topic task plannerUse these tasks to adapt the Exemplar topic plan to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AB or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.

Task Level NC Type Objectives Skills 1 KC 2 KP 3 RC 4 CO

Starter 1 M/S 4 Practical 1–3 PLTS (Ct, Ep) 1a 2a c

Starter 2 M/S 4 Classwork 1–3 PLTS (Ct) 2a

Starter 3 M/S 4–6 Classwork 1–3, 4, 8 PLTS (Rl) 1a 2a

Starter 4 M/S 4–6 Classwork whole unit PLTS (Rl) 2a

Exploring 1 M/S 4 Classwork 4, 6 ICT (SS) 2a c, e

Exploring 2 M/S/C 4–5 Practical 2, 3, 4, 7 1a, 1b, 1c, 2a, 2b 2a c

Exploring 3 M/S/C 4 Practical 1 Lit (WF) 1a, 1b, 1c, 2a 2a

Exploring 4 M/S 4–5 Practical 1, 5, 8 1b 1a, 1b, 1c, 2a 2a

Explaining 1 M/S 4–5 Classwork 1–3, 5, 7, 8 Lit (WF) 2a c

Explaining 2 M/S 4 Practical 2 1c 2a

Explaining 3 C 6 Classwork 10 3a 2a a, c

Plenary 1 M/S/C 4 Classwork 1–3 PLTS (Ct) 2a

Plenary 2 M/S 4–6 Classwork 1–3, 4, 8 PLTS (Rl) 1a 2a a

Plenary 3 M 4 Classwork 1–3, 5 Lit (WF) 2a

Homework 1 M 4 Homework 1, 2 Lit(WF) 2a

Homework 2 M 4 Homework 1–4 2a c

Homework 3 S 4 Homework 2–6 Lit (EC) 2a c

Homework 4 C 4–6 Homework 9 Lit(EC) 2a c

Starters

1: Practical: Making teaMake a cup of tea in a beaker by pouring hot or boiling water onto a tea bag. Then write a list of questions on the board and ask pupils to discuss the answers in pairs. After a few minutes, ask each pair to join with another pair, and each group of four should decide on the best answers to each question before having a whole-class feedback session. Suitable questions include:

• Describe what you saw happening (elicit words such as transparent, colourless, coloured if necessary).

• What is the tea bag for?• Why can the coloured water get through the tea bag?• What other things at home need separating? (Answers could

include fi lters for making ‘real’ coffee, or sieves for getting lumps out of fl our or chips from fat.)

A possible alternative is making coffee from ground beans using a fi lter or a cafetiere. But no drinking it in the lab!

Take care when using hot water.

ResourcesBeaker; tea bag. Optional: ground coffee, cafetiere or coffee fi lter.

2: Thinking about dissolving (AT)Afl Use some or all of the following thinking skills questions to

fi nd out how much pupils recall about dissolving and fi ltering from Key Stage 2.

• OOO: solution, solvent, solute. (Possible answers: the solute is the only solid (although, technically, a liquid such as ethanol can be said to dissolve in water); the solution is the only one that contains more than one substance, or it is the only mixture; the solute is the only one that can be a solid.)

• OOO: sand, salt, sugar. (Possible answers: sand is the only one that is not soluble in water, it is the only one we do not eat; sugar is the only one not found naturally at the seaside.)

• OOO: tea, instant coffee, fi lter coffee. (Possible answers: instant coffee is the only one that dissolves completely in water and it is the only one that does not need a fi lter; tea is the only one made from leaves.)

• OOO: fl our, chalk, sugar. (Possible answers: sugar is the only one that dissolves in water; chalk is the only one that is not a food, and is the only one made from a rock.)

• OOO: tea bag, chip basket, sieve, saucepan. (Possible answers: the saucepan is the only one that cannot fi lter mixtures; tea bag is the only one made of paper, and is the only one containing a food substance.)

• PMI: sand should be soluble. (Possible answers: P – sand could be transported more easily in a solution; M – beaches would disappear as the sand would dissolve in the sea; I – what would people do for holidays?)

The second AT presentation link on page 65 opens Thinking about dissolving – a PowerPoint presentation version of this task.

3: Ideas about mixtures and solutions ATAfl The second AT presentation link on page 64 opens Ideas

about mixtures and solutions – a presentation with different ideas about mixtures and solutions, some of which are correct and some are not. The presentation also includes answers. This presentation can also be used for Plenary 2, in which case you may just wish pupils to jot down answers to be referred to later.

4: Quick QuizAfl Use the 8E Quick Quiz for baseline assessment for this unit.

Pupils could record their answers on the 8E Quick Quiz Answer Sheet.

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Exploring tasks

1: Pupil’s Book page 63 (AT)This page introduces the idea that we have a plentiful supply of clean, safe water in the UK, but that people in other countries are not always so fortunate. The questions should help pupils to revise earlier work on the water cycle and fi ltering.

• The AT video link opens Water companies – a clip showing Tina Dijkstal from Southern Water talking about how she became a hydrogeologist and what she does. She also gives some examples of how much water is used and how much the company supplies.

• The AT spreadsheet link opens Using water – a spreadsheet to help pupils to calculate how much water their household uses and to draw pie charts showing the volumes used for different uses. You could follow this up by asking pupils to estimate usages for families in different circumstances (e.g. more young children, an elderly person living alone, etc).

2: Practical: Soil fi lterThe Practical box on page 65 of the Pupil’s Book suggests that pupils design a soil fi lter that could be used for survival in the countryside.

• Must: pupils follow the instructions on Worksheet 8Ea(2) to build their fi lter, and then complete the exercise at the bottom of the sheet to explain how it works.

• Should: Worksheet 8Ea(3) provides brief instructions for the construction of the fi lter, and then asks pupils to investigate how fast their fi lter works.

• Could: pupils could be asked to design their own fi lter based only on the prompt in the Pupil’s Book and/or materials provided, and asked to design their own investigation. They should evaluate each other’s fi lters based on scientifi c tests to award one group/pupil with a ‘best design’ award.

Do not allow pupils to drink their water. It could still be contaminated.

Resources (per group)Plastic drinks bottle (bottom removed – ensure there are no sharp edges); moss or grass; ruler; small stones; sand (or soil); muddy/dirty water to fi lter (with bits of grass, twigs, etc.); stopclock; beakers; bucket to collect waste; Worksheets 8Ea(2) or 8Ea(3).

3: Practical: Testing solubilityProvide pupils with a selection of solids and ask them to mix a spatula of each with water in a test tube or boiling tube. The mixture can be stirred with a spatula or glass rod. Pupils should be encouraged to use appropriate vocabulary to describe the resulting mixture, and then come to a judgement about whether the solid is soluble or insoluble.

• Should: ask pupils to explain how they are making judgements about what is soluble and what is not.

With some groups it may be appropriate to introduce additional gradations such as ‘partially soluble’, ‘mostly soluble’, and so on. You could also include some liquids.

• Could: a light meter could be used to measure the amount of light coming through each test tube.

Note that Exploring 1 in Topic 8Eb looks at solubility in a more quantitative manner.

Aspirin can be harmful.

Resources (per group)8 test tubes or boiling tubes; glass rods; spatulas.Suggested list of solids: sugar, salt, fl our, instant coffee or tea, aspirin*, soap, pepper, baking soda.(*A brand such as Aspro ClearTM will dissolve completely.)

4: Practical: Effectiveness of solventsPupils compare the effectiveness of solvents in removing different types of marks. It is suggested that you keep a class set of ‘offcuts’ for this practical – for example material from discarded work surfaces, whiteboards or polished wood. A piece of the board (about 20 cm × 10 cm would be a suitable size) can be marked using a variety of substances, for example ball point pen, washable marker pen, permanent marker, wax crayon and liquid paper, and the marks labelled. Pupils should be given the opportunity to see which of these can be removed easily with a damp cloth. For those marks that are not easily removed in this way, other solvents should be tried, for example ‘meths’ (now called Industrial Denatured Alcohol), white spirit or propanone (acetone).

Industrial Denatured Alcohol is highly fl ammable and harmful. Propanone is an irritant and highly fl ammable. White spirit is harmful and fl ammable. Ensure there are no naked fl ames in the lab. This practical should be carried out in a well-ventilated laboratory. Eye protection should be worn.

Resources (per group)Wooden or work surface ‘offcuts’ (about 20 cm × 10 cm) marked with (at least three from) biro, marker pens, nail varnish, liquid paper, wax crayon; access to solvents (e.g. Industrial Denatured Alcohol, propanone, white spirit); cloths; disposable gloves (preferably nitrile, not latex); eye protection.

Explaining tasks

1 Pupil’s Book pages 64–65 (AT)These pages look at mixtures, fi ltering and dissolving. Worksheet 8Ea(1) is the Access Sheet.

• Must: read through the text with pupils and ask them to answer the questions.

• Should: pupils should remember most of this work from KS2. However, it is worth confi rming this before moving on to the rest of the unit. This can be done by giving pupils the top half of the Access Sheet only, and asking them to write their own defi nitions of the words. They should try this without reference to the book at fi rst, but could then use the book to check their defi nitions.

• The AT video link on page 64 opens Filtering water supplies – a clip showing Tina Dijkstal explaining how river water is fi ltered at the treatment works before being disinfected and fed into the water supply.

• The second AT presentation link on page 64 opens Ideas about mixtures and solutions – see Starter 3 and Plenary 2.

• The AB document link on page 64 opens Other mixtures – see Explaining 3.

2: Practical: How to fi lterDemonstrate how to use fi lter paper and a funnel to fi lter in the lab. Let pupils practise this to produce clean water from pure water plus dirt or from salt solution plus dirt. The products from this process could then be kept to use in the following topic.

Resources (per group)Funnel; fi lter paper; beaker; conical fl ask; samples of dirty water.

8Ea Using water

8Ea

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Using water 8Ea

8Ea

3: Other mixtures ATThe AB document link on page 64 opens Other mixtures – which explains how scientists classify mixtures of solids, liquids and gases. Pupils are asked to create a document giving examples of the different kinds of mixtures, and a few photos are provided to help them to get started. Alternatively, they could make posters or computer presentations.

Plenaries

1: Quick CheckAfl The Quick Check sheet provides a set of answers – ask pupils

to suggest what the questions were. In some cases, pupils may be able to suggest more than one question that would result in the answer given. Encourage pupils to use the key words from this topic in their questions. Give pupils a few minutes to work on this alone or in groups, then report back to the rest of the class.

• Must: pupils write questions for answers 1 to 5.• Should: pupils write questions for all answers on the sheet.• Could: pupils attempt to write at least two different questions for

each answer on the sheet.

2: Mixtures and solutions revisited ATAfl The AT presentation link on page 64 opens Ideas about

mixtures and solutions – a concept cartoon with different ideas about mixtures and solutions, some of which are correct and some are not. The presentation also includes answers. If this presentation has already been used in Starter 3, ask pupils to look at their earlier answers and amend them as necessary before discussing the answers with them.

3: I can… cloze exercise AB/ATAfl The AB document link on page 65 opens a cloze exercise

covering the material on pages 64–65. There is also an AT presentation version with answers.

Homework tasks

1: Worksheet 8Ea(4) provides a crossword to help consolidate pupil’s knowledge of the scientifi c vocabulary covered in this topic.

2: Worksheet 8Ea(5) provides questions on fi ltering in domestic situations.

3: Worksheet 8Ea(6) provides questions based on water and its importance for life.

4: Worksheet 8Ea(7) looks at how our water is treated before being supplied to homes.

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Pupil’s materials


Solubility All PB pp66–67 Classwork Explaining 1

8Eb Quick Check Must/Should ASP Classwork Plenary 2

8Eb Word Sheet Must ASP Classwork

8Eb(1) Solubility Must CHAP Access Explaining 1

8Eb(2) Dissolving and particles Must/Should CHAP Classwork Starter 2

8Eb(3) Temperature and solubility 1 Must CHAP Practical Exploring 2

8Eb(4) Temperature and solubility 2 Should CHAP Practical Exploring 2

8Eb(5) How much will dissolve? 1 Must CHAP Homework Homework 1

8Eb(6) How much will dissolve? 2 Should CHAP Homework Homework 2

8Eb(7) Dissolving gases Could CHAP Homework Homework 3


(1) explain that a dissolved solid breaks up into very tiny pieces(2) explain how to make a solid dissolve more quickly(3) recall that there is a limit to the amount of solid that will

dissolve in water, and use a graph to fi nd out how this varies with temperature.

Most pupils should: (4) explain why the mass of a solution is the sum of the

masses of the solute and solvent(5) explain fi ltering using ideas about particles(6) recall that the limit of solubility will be different for different

solutes(7) recall that for most solutes, more solid will dissolve when the

water is hotter.Correctly use the words saturated, solubility.

Some pupils could: (8) recall that all solids dissolve to some extent(9) be able to use a quantitative defi nition of solubility (10) recall that gases dissolve in water, and that their solubility

changes with temperature.


ActiveTeach from the link next to the initiator question.• Pupils should have looked at variables that affect the speed at

which a solid dissolves at KS3. The practical activities suggested here look at how much solid will dissolve.

• Misconception: the word saturated may have been encountered in the context of a cloth or sponge being ‘saturated with water’. The idea of saturation by a solid is likely to be a new one, and care has to be taken to avoid any misconception of its meaning here. The use of the word ‘saturated’ is consistently used in science to mean ‘containing as much as possible’, but the key question is ‘As much of what?’ Since the everyday meaning relates to saturation with water, the idea that more water will make a solution less saturated is likely to run counter to ‘common sense’. You should emphasise that in this case we are focusing on the amount of solid – the solution is saturated when it contains as much solid as possible.


MUST

PB pages 66–67

Starter 1Explaining 1Exploring 2Plenary 3Homework 1

SHOULD

PB pages 66–67

Starter 1Starter 2Explaining 1Exploring 2Plenary 2Homework 2

COULD

PB pages 66–67

Starter 1Starter 2Explaining 1Exploring 2Plenary 1Homework 3

SHOULD 2 Yr KS3*

PB pages 64–67

8Ea Starter 18Ea Explaining 18Eb Explaining 18Eb Exploring 28Eb Plenary 28Eb Homework 2

*This table is repeated in 8Ea.

Solubility8Eb

8Eb

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Solubility 8Eb

8Eb

Topic task plannerUse these tasks to adapt the Exemplar topic plan to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AB or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S/C 4–5 Practical 3, 4 1a 2a

Starter 2 M/S 4–5 Classwork 3, 4 1a, 1b, 1c, 2a, 2b 2a

Exploring 1 M/S 4–5 Practical 3, 6 1a, 1b, 2a

Exploring 2 M/S/C 4–8 Practical 3, 6, 7 PLTS (Tw) 1a, 1b, 1c, 2a, 2b, 3a 2a

Exploring 3 M/S 4–5 Practical 3 PLTS (Tw) 1a, 1b, 1c, 2a 2a

Explaining 1 M/S 4–5 Classwork 1, 3–7 2a

Explaining 2 S/C 5–6 Classwork 6, 7, 9 Num (L) 2a

Plenary 1 S/C 5–6 Practical 6, 7 1a 2a

Plenary 2 M/S 4–5 Classwork 1, 3, 7 PLTS (Rl) 2a

Plenary 3 M 4–5 Classwork 1, 3–7 Lit (WF) 2a

Homework 1 M 4–5 Homework 3 Num (L) 2a

Homework 2 S 4–5 Homework 3, 6, 7 Num (L) 2a

Homework 3 C 5–6 Homework 10 Num (L), Lit (EC) 2a c

Starters

1: Practical: Dissolving and mass Have a couple of beakers of water ready and a balance. Let pupils see you fi nding the mass of the beaker of water, and the mass of some sand and some salt.

Ask pupils to work in groups of 2 to 4 to discuss the answers to questions such as:

• Must: what will happen to the sand if I add it to the water? What will happen if I put the salt in the water? What will happen if I keep adding more salt? Will this change if I heat up the water?

• Should: what will the mass be if I add the sand to the water? What will happen to the mass when I add the salt to the water? Explain these answers. Will more sugar dissolve or more salt?

• Could: how will the amount that dissolved change if there is more water?

Ask for feedback on each question as you work through the demonstrations, if necessary eliciting the idea that all the original particles of salt (sodium chloride) are still present in a solution, even if they cannot be seen. Pupils may realise from their own experience, or from KS2 work, that there is a limit to the amount of a solute that will dissolve in a certain volume of water.

ResourcesBeakers of water; sand; salt; balance; stirring rod.

2: Solvents and solutions (AT)Afl Worksheet 8Eb(2) provides a set of drawings of solvents and

solutions for pupils to cut out and match up. Pupils’ responses will let you see if they have grasped the idea of conservation of mass on dissolving, and the idea of saturated solutions.

The second AT presentation link on page 66 opens Solutions before and after – this provides the same drawings as on the worksheet so that this activity can be done as a class discussion.

Exploring tasks

1: Practical: How much salt/sugar will dissolve? Salt and sugar are suggested in the Pupil’s Book as suitable examples of solutes which might dissolve in different amounts. Note that the solubility of sodium chloride at 25 °C is approximately 36 g/100 ml, whereas the solubility of sucrose is over 200 g/100 ml. You may therefore wish to encourage pupils to use small volumes of water.

• Must: pupils can follow a simple method based on, for example, counting the number of spatulas of solid that will dissolve in a given volume of water.

• Should: pupils should be encouraged to develop a more sophisticated approach based on measuring out masses of solid. The solid should be added until no more dissolves.

Resources (per group)Salt; sugar; beaker (10 cm3); spatula. Optional: access to balances.

2: Practical: Temperature and solubility Pupils can be asked to investigate the effect of the temperature of a solvent on the solubility of a solute. A variety of methods are possible.

• Must: Worksheet 8Eb(3) presents the simplest method, whereby students fi nd out how many spatulas of potassium chloride (referred to as ‘salt’ on the worksheet, for simplicity) dissolve in a fi xed quantity of water at different temperatures. Ensure that pupils understand that it is the quantity of solute they are investigating, not how fast it dissolves. If you have water baths available, pupils should stand their beakers in water at appropriate temperatures. If not, then pupils should be encouraged to realise that if they heat the water to the appropriate temperature, and then put salt in, the water will be cooling down while they carry out their experiment.

• Should: a more accurate method is to prepare hot solutions with different quantities of solute, and cool them until crystals start to appear. This method is outlined on Worksheet 8Eb(4), which suggests using copper sulphate, as the formation of coloured crystals will be easier to see. If time permits, pupils can prepare a range of solutions, or each group can be allocated a particular mass of solute and results can be pooled. Alternatively,

M05_TTPG_5453_U04_5p.indd 145 12/9/08 12:47:16


different groups can investigate the solubility of different salts with temperature. Pupils can produce graphs of solubility against temperature.

If there is time, pupils could be encouraged to plan this practical before they are given the method on Worksheet 8Eb(4). Pupils should attempt to identify the variables in this experiment and also any possible safety issues. You could discuss with them the diffi culty of deciding on an end point and how they will record their results. At the end of practical lesson, you could discuss with pupils the reliability of their results and if they have suffi cient data to be able to draw a conclusion. Any suggestions about improvements to the practical should be accompanied by a reason for the suggested change. Pupils could also be encouraged to pool their results and think about how these could be manipulated to help provide further evidence for their conclusion.

• Could: pupils could be asked to extend their investigation to the solubility of various substances in different solvents.

This practical can be used to carry out an AT1 investigation. A set of level descriptions is provided on pages 153–154 of the ASP.

Eye protection should be worn. Copper sulphate is harmful.

Resources (per group)Potassium chloride; boiling tube; spatula; heating apparatus or access to kettle; access to balances (optional); Worksheets 8Eb(3) or 8Eb(4); eye protection.

3: Practical: How fast does sugar dissolve? The time taken for materials to dissolve can be investigated in the laboratory using sugar as an example. In this case a number of variables could be investigated, e.g. temperature, amount of solute, volume of solvent, type of sugar (granulated, caster, lump, etc.). This experiment can also be adapted to be carried out at home. Note that most pupils will have carried out an experiment into the speed of dissolving at KS2, but may not have investigated all the variables listed.

Resources (per group)Sugar (granulated, caster, lump, etc.); water; stopclock; beakers; heating apparatus; thermometer; spatulas; access to balance; mortar and pestle; copper sulphate.

Explaining tasks

1: Pupil’s Book pages 66–67 (AT)These pages introduce the idea that the total mass of a solution is the sum of the masses of the solvent and solute, and explain dissolving in terms of particles. The idea of saturated solutions and different solubilities is then introduced. Worksheet 8Eb(1) is the Access Sheet.

• The fi rst AT animation link on page 66 opens Dissolving – an animation showing what happens to particles when something dissolves.

• The second AT animation link on page 66 opens Filtering – an animation showing fi ltering in terms of what happens to the particles.

• The second AT presentation link on page 66 opens Solutions before and after – see Starter 2.

• The fi rst AB document link on page 67 opens Different solubilities – see Explaining 2.

2: Solubility AB/ATThe AB document link on page 67 opens Different solubilities – this document provides a graph showing how the solubilities of different salts change with temperature, and includes comprehension questions. This is best used after pupils have worked through the material in the Pupil’s Book.

• Should: project the graph using an interactive whiteboard, and discuss the answers to the questions.

• Could: pupils can work through the questions individually or in pairs.

Plenaries

1: Practical: Snowstorm in a test tube Lead iodide provides a very good visual demonstration of the change of solubility with temperature, although this does not lead to the production of large crystals. Heat a little lead iodide in a boiling tube about half full of distilled water. Alternatively, the lead iodide may be precipitated by mixing equal volumes of dilute potassium iodide and lead nitrate solutions. The solid will dissolve when the water is close to boiling point. Allow the solution to cool slowly and crystals of lead iodide will precipitate as a ‘golden snowstorm’ effect – the glittering crystals give quite a spectacular effect as they fl oat in the water. Once a set of tubes has been set up, they can be re-used repeatedly.

Show pupils the demonstration, and ask them to explain why it happens.

Lead compounds are toxic. Wash hands after handling them. Eye protection should be worn.

ResourcesBoiling tubes; lead iodide (solid); 250 cm3 beakers. Alternatively, use dilute lead nitrate and potassium iodide solutions (0.005 mol dm–3); eye protection.

2: Quick CheckAfl The 8Eb Quick Check sheet provides a set of questions for

pupils to classify as true or false. Pupils should write a correct version of any statements they decide are false, or be asked to explain their reasoning.

• Must: pupils answer questions 1 to 4.• Should: pupils answer all questions.



Homework tasks

1: Worksheet 8Eb(5) provides data handling questions on solubility.

2: Worksheet 8Eb(6) provides data handling questions on solubility. Pupils will also need a sheet of graph paper.

3: Worksheet 8Eb(7) looks at the solubility of gases in water, and at how places such as power stations that put warm water back into waterways can affect wildlife.

8Eb Solubility

8Eb

M05_TTPG_5453_U04_5p.indd 146 12/9/08 12:47:16


Salt of the Earth8Ec

8Ec

Pupil’s materials


Salt of the Earth All PB pp68–69 Classwork Explaining 2

8Ec Quick Check Must/Should ASP Classwork Plenary 1

8Ec Word Sheet Must ASP Classwork

8Ec(1) Salt of the Earth Must CHAP Access Explaining 2

8Ec(2) Investigating water 1 Must CHAP Practical Exploring 1

8Ec(3) Investigating water 2 Should CHAP Practical Exploring 1

8Ec(4) Evaporating Must/Should CHAP Practical Explaining 1

8Ec(5) Making salt from rock salt 1 Must CHAP Practical Exploring 2

8Ec(6) Making salt from rock salt 2 Should CHAP Practical Exploring 2

8Ec(7) Hard water? 1 Must CHAP Homework Homework 1

8Ec(8) Hard water? 2 Should CHAP Homework Homework 2

8Ec(9) Gandhi and the Salt Act Could CHAP Homework Homework 3


(1) recall that water usually contains dissolved chemicals(2) explain that a dissolved solid can be obtained from a liquid

by evaporating the liquid(3) carry out evaporation safely in the laboratory.

Correctly use the words common salt, evaporation, salts.Most pupils should:

(4) recall that salt can be obtained from sea water by evaporation or from salt mines

(5) explain how to obtain pure salt from rock salt(6) recall some differences between hard and soft water.

Correctly use the words brine, hard water, quality standards, rock salt, soft water.

Some pupils could: (7) recall some facts about Gandhi and the Salt Act.

Topic notes• Targets for the lesson can be accessed via the ActiveBook or

ActiveTeach from the link next to the initiator question.• Pupils should have covered the evaporation of a solution to

obtain a dissolved solid at KS2, but may not have carried out the procedure with standard laboratory equipment.

Be prepared: 8Ec Starter 2: samples of hard and soft water.Explaining 3: dried peas or lentils.


MUST

PB pages 68–69

Starter 1Explaining 1Explaining 2Exploring 2Plenary 4Homework 1

SHOULD

PB pages 68–69

Starter 1Explaining 1Explaining 2Exploring 2Plenary 2Plenary 1Homework 2

COULD

PB pages 68–69

Starter 1Explaining 1Explaining 2Exploring 2Plenary 2Plenary 3Homework 2 Homework 3

SHOULD 2 Yr KS3*

PB pages 68–71

8Ec Starter 18Ec Explaining 18Ec Explaining 28Ed Explaining 28Ed Exploring 28Ed Plenary 18Ed Homework 2

*This table is repeated in 8Ed.

M05_TTPG_5453_U04_5p.indd 147 12/9/08 12:47:17


Topic task plannerUse these tasks to adapt the Exemplar topic plan to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S 4 Practical 2 PLTS (Ct) 1a 2a

Starter 2 M/S 4 Practical 1, 6 2a

Exploring 1 M/S 4–5 Practical 1-3 1a, 1b, 1c, 2a, 2b, 2a

Exploring 2 M/S/C 4–5 Practical 2, 3, 5 1b, 1c, 2a 2a

Exploring 3 M/S 4–5 Practical 1, 6 1a, 1b, 1c, 2a, 2b, 2a

Exploring 4 M/S 4–5 Classwork 1 ICT (SS), Num (B) 2a

Explaining 1 M/S 4 Practical 3 1c 2a

Explaining 2 M/S 4–5 Classwork 1, 2, 4, 6 2a c

Explaining 3 M/S 5–7 Practical 1, 6 PCTS (Tw) 1a, 1c, 2a, 2b, 3a 2a a

Plenary 1 M/S 4–5 Classwork 2, 3, 5 2a

Plenary 2 M/S 4–5 Classwork 2, 3, 5 1b 2b 2a

Plenary 3 S/C 5–6 Classwork 2, 4 2a c

Plenary 4 M 4–5 Classwork 1, 2, 4, 6 Lit (WF) 2a

Homework 1 M 4–5 Homework 1 Num (B) 2b 2a

Homework 2 S 4–5 Homework 1, 6 Lit (EC) 2b 2a c

Homework 3 C 5 Homework 7 Lit (EC) 2a c, k

Starters

1: Practical: Separating sand and salt Show pupils a small pile of salt, then mix it with some sand and ask pupils to work in small groups to suggest a way of separating the salt and sand again.

• Must: show pupils a beaker of water, fi ltering and heating apparatus to act as a hint.

• Should: pupils should work out a method without seeing the apparatus.

Pupils will have allowed solutions to evaporate to dryness at KS2, but may not remember the details of what they did, or have had the opportunity to heat a solution to obtain a dissolved solid.

Eye protection must be worn when heating.

ResourcesSalt; sand; beaker of water; heating apparatus; eye protection.

2: Practical: Hard water (demonstration) Put pupils into groups and give each group samples of hard water and soft water mixed with soap solution. Put this into context by telling them that the different samples have come from different parts of the country. Ask the groups to shake the tubes and to comment on what they observe. Elicit the idea that the two samples of water must have different chemicals dissolved in them, and ask for suggestions as to how this can be determined. If necessary, ask what will happen if the water is heated. Pupils will have allowed solutions to evaporate to dryness at KS2, but may not remember the details of what they did, and may not have had the opportunity to heat a solution to obtain a dissolved solid.

Resources (per group)Samples of hard and soft water; soap solution; boiling tubes.If you are in a hard water area, use distilled water for your soft water. If you are in a soft water area, add approximately 0.45 g of calcium sulphate per litre of water to make up the hard water sample.

Exploring tasks

1: Practical: Investigating water Pupils analyse three or more different water samples to determine how pure they are – the most pure will contain the least dissolved solid. Heating a known and fi xed volume of each of the water samples will enable a fair comparison to be made. If you make up water samples for use (from distilled water plus different quantities of salts), keep a note of the quantities used to help you to assess the accuracy of pupils’ fi ndings.

You may wish to carry out Explaining 1 (demonstrating how to evaporate a solution to dryness safely) before pupils carry this out.

• Must: instructions are provided on Worksheet 8Ec(2).• Should: an apparatus list and hints for pupils to plan their own

method are provided on Worksheet 8Ec(3).

Check pupils’ plans before they start. Eye protection must be worn.

Resources (per group)Measuring cylinder; balance; labelled water samples (made up with different quantities of dissolved salts); evaporating basin; heating apparatus; eye protection; Worksheet 8Ec(2) or 8Ec(3).

2: Practical: Salt from rock salt Pupils can obtain samples of pure salt from rock salt. This will provide further practice in the techniques of fi ltering and evaporation.

You can give this practical a context by providing ‘samples’ of rock salt from different mines, and ask pupils to determine which would be the best ‘mine’ to use for making salt. They should be encouraged to use distilled water to avoid any salts in tap water affecting their results.

You may wish to carry out Explaining 1 (demonstrating how to evaporate a solution to dryness safely) before pupils carry this out.

• Must: show pupils how to do the practical, and then ask them to use Worksheet 8Ec(5) to explain the process.

• Should: pupils follow the instructions on Worksheet 8Ec(6) and answer the questions.

8Ec Salt of the Earth

8Ec

M05_TTPG_5453_U04_5p.indd 148 12/9/08 12:47:17


Salt of the Earth 8Ec

8Ec

• Could: ask pupils to work in groups to plan their own method, and to explain the reasons for each step.

Eye protection must be worn. Do NOT heat the salt to dryness in the evaporating basin. Hot specks of salt will spit out. Stop heating when crystals are forming at the edge and let the last of the water evaporate without heating.

Resources (per group)Rock salt, or a variety of rock salt samples (see below); access to electronic top pan balance; mortar and pestle; evaporating basin; fi lter funnels and papers; beaker; conical fl ask; stirring rod; heating apparatus; eye protection; Worksheet 8Ec(5).

‘Mine’ 4 1 6 3 5 2sand (g) 975 900 850 800 750 700salt (g) 25 100 150 200 250 300

If possible, different grades and/or colours of sand should be used to alter the appearance of the samples.

3: Practical: Testing water for hardness (AT)Ask pupils to test different samples of water for hardness, by shaking up a sample of water with some soap solution and measuring the height of the lather produced. Pupils will have seen what happens if you have carried out Starter 2. If this has not been done, the fi rst AT presentation link on page 69 opens Testing water for hardness – which shows the effects of adding different quantities of soap solution to different water samples. Pupils should discuss how to measure the results of the practical and how the observations are appropriate to the task.

• Must: show pupils what to do, and ask them to test and rank the samples in terms of hardness.

• Should: ask pupils to plan a fair, quantitative investigation, and write a report stating the relative hardness of the different samples in terms of the height of lather formed.

Resources (per group)Numbered water samples made up using distilled water and calcium sulphate (see below); boiling tubes; measuring cylinders; soap solution; ruler.

Water sample 5 1 3 2 4 5Mass of calcium sulphate per litre (mg)

0 40 80 120 160 180

4: Salts in water AB/AT The AT spreadsheet link on page 69 opens Salts in water – which provides details of the masses of different salts found in different samples of water. Pupils are asked to use this to plot different kinds of chart to compare the different waters and to decide which kind of chart shows the data most effectively.

Explaining tasks

1: Practical: Evaporating Demonstrate or let pupils practise evaporation of a solution to dryness. Instructions are provided on Worksheet 8Ec(4).

Heat a solution until a little remains so that the solid can be formed as the heat stored in the watch glass or evaporating basin evaporates this remaining amount. This will stop the solid residue from ‘spitting’ at the pupils and also limit the number of breakages! This process is known as heating to dryness. If the solid is heated beyond this point, it may ‘jump’ out of the container and be changed by the heat.

Copper sulphate is harmful when solid or in concentrated solution. Eye protection must be worn.

Resources (per group)Evaporating basin; copper sulphate solution; heating apparatus; beaker; eye protection; Bunsen burners; Worksheet 8Ec(4).

2: Pupil’s Book pages 68–69 (AB/AT)These pages explain that almost all water contains some dissolved salts, and introduces evaporation as a way of fi nding out how much salt is in the water. Worksheet 8E(1) is the Access Sheet.

• The AT video link on page 69 opens Hard and soft water – the video shows Tina Dijkstal talking about why some areas have hard water and some have soft water.

• The fi rst AT presentation link on page 69 opens Testing water for hardness – see Exploring 3.

• The AT spreadsheet link on page 69 opens Salts in water – see Exploring 4.

• The third AT presentation link on page 69 opens Extracting salt – see Plenary 2.

• The fi rst AT document link on page 69 opens Solution mining – see Plenary 3.

3: Practical: Modelling fi ltration and evaporation (demonstration)This demonstration can be linked to Exploring 2 which asks pupils to extract salt from rock salt. Show pupils a mixture of fl our, powdered copper sulphate and dried pea or lentils. The fl our represents the water, the copper sulphate is the salt and the peas represent the sand and dirt. Shake the mixture in a sieve, collecting the fl our and copper sulphate in a basin below. Pupils should understand that the sieve is acting as the fi lter paper would. Ask pupils to think about this as a model and to relate it to their knowledge of particles.

Resources (per demonstration)Flour, powdered copper sulphate (or other coloured powder), dried peas or lentils, sieve, basin.

Plenaries

1: Quick CheckThe 8E Quick Check sheet contains a set of cards that can be sorted to describe how to separate salt from rock salt, and to explain what happens at each stage. These should be cut up beforehand. Pupils can sort the cards individually or in groups.

2: Extracting salt ATThe third AT presentation link on page 69 opens Extracting salt – this shows two groups of pupils extracting salt from rock salt.

Show pupils all the cartoons, and ask them to note on the fi nal one which group has produced the most salt from their original sample of rock salt (Group A). Then go through the cartoons again one by one, asking what Group A did better than Group B, and why this would make a difference. This is an opportunity to revise aspects of dissolving and fi ltering as well as evaporation.

3: Solution mining ATThe fi rst AT document link on page 69 opens Solution mining – this presents a diagram of solution mining, and poses questions aimed at revising aspects of dissolving and evaporation.



Homework tasks

1: Worksheet 8Ee(7) provides simple questions on hard water. 2: Worksheet 8Ee(8) provides questions on hard water, with an

element of comprehension.3: Worksheet 8Ec(9) looks at Gandhi and the Salt Act.

M05_TTPG_5453_U04_5p.indd 149 12/9/08 12:47:18


Pupil’s materials


What’s in a solution? All PB pp70–71 Classwork Explaining 2

8Ed Quick Check Must/Should ASP Classwork Plenary 1

8Ed Word Sheet Must ASP Classwork

8Ed(1) What’s in a solution? Must CHAP Access Explaining 2

8Ed(2) Chromatography of ink Must CHAP Classwork Explaining 3

8Ed(3) Getting it right Should/Could CHAP Classwork Exploring 3

8Ed(4) Chromatography Must CHAP Homework Homework 1

8Ed(5) Who scraped the gatepost? Should CHAP Homework Homework 2

8Ed(6) Forensic evidence Could CHAP Homework Homework 3

SS54 Chromatography All Year 7 CHAP Skills Sheet Exploring 1, Exploring 3


(1) recall what chromatography is(2) be able to make a chromatogram(3) describe how chromatography can be used to separate

colours in inks(4) interpret a chromatogram to draw a conclusion.

Correctly use the word chromatography.Most pupils should:

(5) explain how chromatography works and what it is used for(6) recall that there are different types of chromatography for

different applications. Correctly use the word chromatogram.

Some pupils could:(7) recall some applications of chromatography.


ActiveTeach from the link next to the initiator question.• Although specialist chromatography paper can be obtained,

the practicals suggested work just as well with fi lter paper. For simplicity, the worksheets accompanying this topic refer to ‘fi lter paper’ as opposed to ‘chromatography paper’.

Be prepared: 8Ed Starter 1: pre-prepared chromatogram (optional).Exploring 1, 2 and Practical 3: access to means of drying fi lter papers.Exploring 2 and Practical 3: a range of food colourings.


MUST

PB pages 70–71

Starter 1Exploring 1Explaining 2Explaining 1Plenary 1Plenary 2Homework 1

SHOULD

PB pages 70–71

Starter 1Exploring 1Explaining 2Explaining 1Exploring 3Plenary 1Homework 2

COULD

PB pages 68–71

Starter 1Exploring 1Explaining 2Explaining 1Exploring 3Plenary 1Homework 3

SHOULD 2 Yr KS3*

PB pages 68–71

8Ec Starter 18Ec Explaining 18Ec Explaining 28Ed Explaining 28Ed Exploring 28Ed Plenary 18Ed Homework 2

*This table is repeated in 8Ec.

What’s in a solution?8Ed

8Ed

M05_TTPG_5453_U04_5p.indd 150 12/9/08 12:47:18


What’s in a solution? 8Ed

8Ed



Starter 1 M/S 4–5 Practical 1, 3 2a

Starter 2 M/S 4 Classwork PLTS (Ep) 2a

Exploring 1 M/S 4–5 Practical 1–5 1c, 2a? 2a

Exploring 2 M/S 4–5 Practical 1–5 1c, 2a 2a

Exploring 3 S/C 4–6 Practical 1–5 1a, 1c 2a c

Exploring 4 M/S/C 4–6 Classwork 5–7 ICT (IR) 2a c

Explaining 1 M 4–5 Practical 5 2a

Explaining 2 M/S 4–5 Classwork 1–5, 7 2a 2a c

Explaining 3 M 4 Classwork 3 2a

Plenary 1 M/S 4–5 Classwork 1–5 2a

Plenary 2 M 4–5 Classwork 1–3 Lit (WF) 2a

Plenary 3 M/S 4–6 Classwork 1–7, previous topics PLTS (Rl) 2a

Homework 1 M 4–5 Homework 3 2a

Homework 2 S 4–6 Homework 4, 5, 7 2a 2a c

Homework 3 C 5–6 Homework 4, 5, 7 Lit (EC) 2a, 2b 2a c, j

Starters

1: Practical: Chromatography introductionDemonstrate chromatography to the whole class as a starter activity. Use a dark-coloured ink that includes a range of different colours to make the chromatogram more interesting (either test different pens containing water soluble inks to fi nd one with a good mix of colours, or make up a mixture of different coloured inks). If time is short, you may wish to have a ready-prepared chromatogram made from the same ink, so that you do not have to wait too long for the water to travel up the paper.

Some pupils may have used chromatography at KS2 to investigate the mix of colours in ink or in the dye used to colour Smarties™, so this starter is a good way of fi nding out what pupilsalready know.

ResourcesMix of coloured ink; chromatography paper or fi lter paper; beaker of water; support for paper; pipette.OR: pre-prepared chromatogram made from a mix of coloured inks.

2: Colour mixturesShow pupils three pots of paint – red, yellow and blue, or tell them that you are about to paint something and have only those three colours. Ask what you should do if you want to paint something orange, purple or green. Follow this up asking pupils to work in small groups to discuss how the police can identify the make (and sometimes model) of a car from a scraping of paint left at a crime scene, or the type of pen used to write a letter or sign a fraudulent cheque. Give pupils 5 minutes to discuss the questions in groups, and then ask them to report back. If necessary, elicit the idea that many colours are made from mixtures of other colours, and could be identifi ed if the component colours could be separated.

Exploring tasks

1: Practical: Chromatography of inks The easiest way to set this up is as shown on Skills Sheet 54 from Year 7 CHAP. Remember to check that you have a variety of felt-tipped pens that have water-soluble inks. It is possible to get a range of black pens that are all water soluble, but that contain different mixtures of coloured inks. The use of a non-water-soluble based black pen will make the point about the solubility of the ink used, but do not get pupils to try this one as their only chromatogram – they will only get frustrated if they have no pattern to see at the end.

Ensure that chromatograms are removed from the solvent before the water soaks to the top/edge. Any labels/marks on the paper should be made in pencil so they are unaffected bythe solvent.

Resources (per group)100 cm3 beaker; water; fi lter paper; scissors; water-soluble ink; access to means of drying fi lter papers; Year 7 CHAP Skills Sheet 54.

2: Practical: Chromatography using food colourings This is similar to Exploring 1, but more easily set up using the second method shown on Skills Sheet 54 from Year 7 CHAP. A small spot of each food colouring should be placed on a different spot along the pencil line. Make sure that the pencil line on the chromatography paper is at least 0.5 cm above the water level in the beaker.

Resources (per group)100 cm3 beaker; water; fi lter paper; scissors; a range of food colourings; access to means of drying fi lter papers; Year 7 CHAP Skills Sheet 54.

M05_TTPG_5453_U04_5p.indd 151 12/9/08 12:47:19


3: Practical: Getting it right Worksheet 8Ec(3) lists some mistakes that could be made when carrying out chromatography, and asks pupils to suggest what could happen if these mistakes are made. This sheet could just form the basis for individual work or a class discussion, or the answers to the questions could be treated as predictions that pupils can then check.

Resources (per group)Water-soluble and permanent inks; large beakers/jars; pencils and rulers; water; square fi lter paper or chromatography paper; samples of food colourings with fi ne pipettes; access to means of drying fi lter papers; Year 7 CHAP Skills Sheet 54.

4: Research different types of chromatography (AB/AT)Ask pupils to fi nd out about different types of chromatography. The fi rst AB document link on page 71 opens Chromatograms – this gives pupils some details and illustrations of different kinds of chromatography and asks them to match up the diagrams and explanations to make posters. Pupils will not be expected to recall details of different techniques, but should appreciate that the chromatograms they have made in the lab are just one way of separating different dissolved substances.

• Must: use the worksheet from the ActiveBook and scissors and glue, and ask pupils to cut out the titles, descriptions and diagrams. Help them to sort them out and briefl y discuss why different techniques are needed.

• Should: give pupils the sheet from the ActiveBook and ask them to work in groups to sort the statements and diagrams. They could use the internet to fi nd out more details of the different methods, or fi nd out some applications.

• Could: give pupils a list of the different techniques only, and ask them to fi nd out how each type works, and its strengths, weaknesses and applications. The phrases given on the worksheet are paper chromatography, thin layer chromatography, chromatograms with colourless substances, gas-liquid chromatography.

Explaining tasks

1: Practical: Biro ink Demonstrate that a chromatogram can be made from a non-water-soluble ink by using a solvent in which the inks do dissolve.

Ethanol is highly fl ammable. Industrial Denatured Alcohol is highly fl ammable and harmful.

Resources100 cm3 beaker; ethanol (or Industrial Denatured Acohol); biro pen or a ‘permanent’ marker pen.

2: Pupil’s Book pages 70–71 (AT)These pages introduce chromatography as a way of separating different substances that are dissolved in water. Worksheet 8Ed(1) is the Access Sheet.

• The AT video link on page 70 opens Chromatography – the animation shows the procedure for producing a chromatogram from orange drinks.

• The fi rst AB document link on page 71 opens Chromatograms – see Exploring 4.

3: Analysing chromatogramsWorksheet 8Ed(2) provides drawings of several different chromatograms, to give pupils further practice in analysing simple chromatograms.

Plenaries

1: Revision notesThe Quick Check sheet provides a set of ‘revision notes’ with mistakes. Ask pupils to spot the mistakes and correct them.

2: I can… cloze exercise AB/ATAfl The AT document link on page 71 opens a cloze exercise


3: Beg of my neighbourAfl Ask each pupil to write down three things that they think the

person sitting next to them should have learnt during this topic (or during the unit so far), and when they would have learnt it. Then ask pupils to ask each other in pairs whether they agree on the things they should have learnt. Ask them to agree a fi nal list of the three most important points.

Homework tasks

1: Worksheet 8Ed(4) provides simple questions on chromatography. 2: Worksheet 8Ed(5) provides questions on chromatography, in a

forensics setting.3: Worksheet 8Ed(6) looks at the use of chromatography in

forensic analysis of DNA samples.

8Ed What’s in a solution?

8Ed

M05_TTPG_5453_U04_5p.indd 152 12/9/08 12:47:19


Still water8Ee

8Ee

Pupils’ materials


Still water Must/Should PB p72–73 Classwork Explaining 1

Focus on: Reservoirs and desalination Could PB p74–75 Classwork Explaining 5

Running out … Must/Should PB p76 Classwork Explaining 6

8E Quick Quiz Must/Should ASP Classwork Plenary 6

8E Quick Quiz Answer Sheet Must/Should ASP Classwork Plenary 6

8E End of Unit Test Must/Should ASP Classwork Plenary 7

8E Level Ladder Must/Should ASP Classwork Plenary 5

8Ee Quick Check Must/Should ASP Classwork Plenary 1

8Ee Word Sheet Must ASP Classwork

8Ee(1) Still water Must CHAP Access Explaining 1

8Ee(2) Supplying water Should CHAP Access Explaining 5

8Ee(3) Distillation Must/Should CHAP Classwork Explaining 2

8Ee(4) Separating mixtures Should CHAP Classwork Plenary 2

8Ee(5) A solar pump 1 Must CHAP Homework Homework 1

8Ee(6) A solar pump 2 Should CHAP Homework Homework 2

8Ee(7) Fractional distillation Could CHAP Homework Homework 3

SS41 Debates and speaking Must/Should Year 7 CHAP Classwork Explaining 6


(1) describe what ‘pure’ water is(2) recall that distillation can be used to separate a liquid from

anything dissolved in it(3) explain that distillation is evaporation followed by

condensation(4) describe some applications of distillation(5) describe some ways in which water supplies can be

conserved.Correctly use the words condensing, distillation, pure, steam, water vapour.

Most pupils should:(6) be able to explain distillation using ideas about particles.

Correctly use the word still.Some pupils could:

(7) recall some of the human and environmental effects of supplying large quantities of water

(8) explain how distillation of sea water provides water in some arid countries

(9) explain that fractional distillation works because each liquid boils at a different temperature

(10) recall some of the products made from crude oil.


ActiveTeach from the link next to the initiator question.

Be prepared: 8Ee Exploring 2: garden trowel, canes/sticks, stones, access to open ground.


MUST

PB pages 72–73

Starter 1Starter 2Exploring 1Explaining 1Explaining 3Plenary 1Homework 1

SHOULD

PB pages 72–73, 76

Starter 1Starter 2Exploring 1Explaining 1Explaining 6Plenary 3Homework 2

COULD

PB pages 72–76

Starter 1Explaining 1Exploring 1Explaining 4Explaining 5Explaining 6Plenary 3Homework 3

SHOULD 2 Yr KS3

PB pages 72–73, 76

8Ee Starter 18Ee Starter 28Ee Exploring 18Ee Explaining 18Ee Explaining 68Ee Plenary 38Ee Homework 2

M05_TTPG_5453_U04_5p.indd 153 12/9/08 12:47:20


Starters

1: The water cyclePupils will have studied the water cycle at KS2, and many will remember that most rain was originally water evaporated from the sea. Give pupils one minute to draw a diagram to show the water cycle. You could give them a start by drawing, on the board, a cloud with some raindrops below it and a sloping line under the cloud. Then ask pupils to share their ideas about the water cycle in groups and explain why rain is not salty. Ask one pupil from each group to give their answer to the rest of the class.

2: Practical: Distillation brainstorm Start by asking pupils to think about evaporating a solution and what is left in the basin, and what they would need to do if it was the water from the solution they wanted to keep, rather than the solute. Put pupils into groups and pose questions for them to discuss in their groups before having a class feedback session.

• Must: show pupils the apparatus needed for simple distillation and ask them to suggest how it works, including any safety precautions they should take.

• Should: ask pupils to work out how to obtain water from a solution without showing them the apparatus fi rst. They should describe the kind of apparatus they would need and how to use it.

• Could: as for Should, but have a further discussion session to see if pupils can work out how to separate two liquids with different boiling points.

ResourcesBunsen burner; tripod; gauze; evaporating basin; heatproof mat.

Exploring tasks

1: Practical: Distilling ink Pupils distil ink using side-arm test-tubes. Ensure that the tube or fl ask is not allowed to boil dry. (If boiling tubes with delivery tubes are used, bungs with two holes will be needed so that a thermometer can be used.) Pupils should be instructed to heat the inky water gently to avoid it bubbling over into the delivery tube. Note that if the apparatus has been used for distilling ink by earlier classes, the water produced may not be clear if earlier users have allowed the ink to boil over.

Eye protection should be worn. Do not fi ll the boiling tube more than 1 / 3 full.

Resources (per group)Side-arm test-tubes, or boiling tubes with delivery tubes; heating apparatus; heatproof mat; inky water; anti-bumping granules; thermometer and bung (to fi t test tubes); collecting beaker; eye protection.

2: Practical: Survival still Pupils produce a survival ‘still’ using a black plastic bag and a clean container. Support the black bag (in a bowl shape), just above some freshly dug/exposed earth on a hot day, with the container under the plastic to catch the drips of condensation. Some possible methods are illustrated below.

Ensure that pupils wash their hands after contact with the soil.



Starter 1 M 4–5 Classwork 1–4 PLTS (Ep) 2a

Starter 2 M/S/C 4–5 Practical 1–4 PLTS (Ct) 2a A

Exploring 1 M 4–5 Practical 1–4 1c 2a

Exploring 2 S 6 Practical 1–4 1b, 1c 2a c

Explaining 1 M 4–5 Classwork 1–4, 6 2a c

Explaining 2 M/S 4–5 Classwork 3 2a

Explaining 3 M/S 4–5 Practical 3 2a

Explaining 4 S/C 5 Practical 3, 6 2a

Explaining 5 S/C 5 Classwork 7, 8 Lit (EC) 2a, 2b 2a c, d, j, g

Explaining 6 M/S 4 Classwork 5 Lit (DS) 2a c, e, g

Plenary 1 M/S 4–5 Classwork whole unit 2a

Plenary 2 S/C 4–6 Classwork whole unit 1a 2a

Plenary 3 S/C 4–5 Classwork whole unit 1a 3a 2a

Plenary 4 M 4–5 Classwork 1–3 Lit (WF) 2a

Plenary 5 M/S 4–6 Classwork whole unit PLTS (Rl, Sm) 2a

Plenary 6 M/S 4–6 Classwork whole unit PLTS (Rl) 2a

Plenary 7 M/S 3–6 Classwork whole unit PLTS (Rl) 2a

Homework 1 M 4–5 Homework 1–4 Lit (EC) 2a c

Homework 2 S 4–5 Homework 1–4 Lit (EC) 2a c

Homework 3 C 5–6 Homework 9, 10 Lit (EC) 2a 2a c

8Ee Still water

8Ee

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Still water 8Ee

8Ee

small stoneto weigh downcentre of plastic

frame madefrom canesand string

freshly dug earth

black plastic fastened to caneswith sticky tape

black plastic

smallstone

largestones

freshlydug hole

cleancontainer

Resources (per group)Black bin liners; garden trowel; string; canes/sticks; stones; sticky tape; clean container (e.g. plastic cup/jam jar); access to open ground.

Explaining tasks

1: Pupil’s Book pages 72–73Start by discussing evaporation, and the fact that it separates a liquid from a dissolved solid, but is only any use if you want the solid. What happens if it is the pure liquid you want? Discuss where the liquid has gone when it evaporates, and how it could be ‘trapped’ and condensed.

These pages look at the process of distillation. Worksheet 8Ee(1) is the Access Sheet.

2: Distillation (AT)Worksheet 8Ee(3) provides a diagram of the distillation apparatus for pupils to label and to add their own explanations of how it works.

• The AT video link on page 72 opens Distilling inky water – this provides an activity where labels have to be dragged and dropped onto a diagram of the distillation apparatus.

• The AT animation link on page 72 opens Distillation – this provides an animation of distillation in terms of particles.

3: Practical: Liebig condenser Demonstrate the distillation of inky water, using a Liebig condenser. Pupils should be told that ink is often made by dissolving solids in water. Heat the fl ask gently whilst the mixture boils. Point out the reading on the thermometer, condensation inside the condenser and collection of the pure water. Discuss with pupils the reason why the water in the cooling jacket goes in at the bottom.

Eye protection should be worn.

ResourcesLong neck, side-arm round-bottomed fl ask; Liebig condenser; water supply; anti-bumping granules; thermometer and bung; Bunsen burner; ink/water mixture; heatproof mat; eye protection.

4: Practical: Distilling alcohol/water Demonstrate the distillation of an alcohol/water mixture using an electric heating mantle to avoid alcohol fumes igniting and giving a fl ash fl ame. Demonstrate to pupils how to smell chemicals safely (fi ll the lungs with clean air, then wave a hand above the container to waft the smell towards you). Identify alcohol by smell (do not allow pupils to take a large sniff or taste it). This demonstration can be more effective if Completely Denatured Alcohol (CDA) is used (but be aware that this is very smelly!) – the dye remains in the fl ask.

Ethanol is highly fl ammable. Completely Denatured Alcohol is highly fl ammable and harmful. Eye protection should be worn. Ensure that pupils smell the distillate following the recommended method.

Resources (per group)Long neck, side-arm conical fl ask; Liebig condenser; water supply; anti-bumping granules; thermometer and bung; electric heating mantle; mixture of 20 cm3 ethanol or Completely Denatured Alcohol to 150 cm3 water; heatproof mat; eye protection.

5: Pupil’s Book pages 74–75 (AB/AT)These pages look at how cities are supplied with water, looking fi rst at where the water for Manchester comes from and considering the environmental and human consequences of different means of supplying water. They then go on to briefl y discuss the use of desalination plants for supplying drinking water.

Worksheet 8Ee(2) is the Access Sheet.

• The AT video link on page 74 opens Supplying water – the clip shows Tina Dijkstal explaining where Southern Water gets its water and contrasts this with water companies in the south west of England.

• The AT animation link on page 75 opens Desalination – this is a diagram of a desalination plant with labels selected from drop-down menus.

6: Pupil’s Book page 76This page looks at different opinions about the use of water in the UK, and how we can make sure that water supplies in the future are adequate.

• The AT video link on page 76 opens Saving water – this shows Tina Dijkstal talking about why there are sometimes water shortages and about some of the ways in which people can use less water in their homes.

The Have Your Say box on this page asks pupils to consider how the government could make sure that the UK has enough water. This can be used as the basis for group discussions or a debate. Refer to Skills Sheet 41 from the Year 7 CHAP for ideas on how to run a debate.

Plenaries

1: Quick Check The Quick Check sheet provides a set of cards summarising the different separation techniques covered in this unit for pupils to match up. Incorrect explanations are also included to test their understanding.

2: Explaining separation techniques (AB/AT)The AB document link on page 72 opens Separation summary – which provides a table for pupils to complete to summarise the four different separation methods covered in this unit.

Worksheet 8Ee(4) provides a diagram illustrating how fi ltering works using the particle model. Pupils are asked to draw similar diagrams to explain how the other ways of separating mixtures work.

3: Water purifi cationTell pupils that the local water company has been receiving complaints about the quality of the water, so it is having an open day at its laboratories. It wants to have some information boards explaining how it treats water, but it also wants to explain the science behind the different ways of purifying water or analysing it to see what salts it contains.

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8Ee Still water

8Ee

Ask pupils to prepare some labelled diagrams explaining how each separation technique works. They should include ideas about particles in their diagrams and/or labels, and information about what each method can be used for. This activity can be done as an assessed task. A set of level descriptions is provided on page 151 of the ASP.



5: Level LadderAfl Pupils should tick the boxes on the Level Ladder to record

those statements that they feel they know. Alternatively they can use a traffi c light system or the CRI index (see Introduction, page 17) to record degrees of certainty. Ideally pupils should be certain of all statements at a level to be sure they are working at that level. Encourage pupils to plan how to do further work on the things about which they remain unsure.

6: Quick Quiz revisitedAfl Revisit the 8E Quick Quiz to test pupils’ knowledge of the

content of this unit. If you have the ASP on CD-ROM use Quick Quiz 2, which provides the same activity but with the answers arranged in a different order. Pupils could fi ll in their answers on the 8E Quick Quiz Answer Sheet. Encourage pupils to identify for themselves areas where their understanding is still weak and decide how they are going to remedy this.

7: End of Unit TestAfl Use the End of Unit Test. A marking guide is given in the

ASP. Encourage pupils to identify areas that are still weak and to formulate plans to strengthen those areas.

Homework tasks

1: Worksheet 8Ee(5) provides questions in the context of a solar-powered water pump that produces distilled water.

2: Worksheet 8Ee(6) provides questions in the context of a solar-powered water pump that produces distilled water.

3: Worksheet 8Ee(7) looks at the use of fractional distillation for separating the components in crude oil.

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