Pupil’s Book A Chapter 2 Changes - nothingnerdynothingnerdy.wikispaces.com/file/view/HW+Expansion.pdf/217931448/... · English. Be careful to make the distinction between material

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RationaleThere has been a deliberate decision to alter the order ofUnits of the QCA/DfES Scheme of Work when writingthese books.

The authors think that the fundamental concept ofParticles and Kinetic Theory needs to be taught at thestart of Year 7. All students of chemistry at secondary levelneeds an understanding of particle arrangement andmotion in solids, liquids, gases and solutions. Certainlybefore looking at acids or chemical reactions, pupils needto be taught the concept of particles in solutions such asacids and alkalis. Similarly, the arrangement of particles ingases needs to be taught in order to achieve a betterunderstanding of combustion.

So the suggested order for teaching these concepts is:

Particle model QCA Unit 7G Hodder ScienceChapter 2

Solutions QCA Unit 7H Hodder ScienceChapter 5

Acids and alkalis QCA Unit 7E Hodder ScienceChapter 8

Chemical changes QCA Unit 7F Hodder ScienceChapter 11

Conceptual developmentThis chapter allows the development of a basic kineticmodel for solids, liquids and gases and uses it to explainthe physical properties and behaviour of those materials.This model also helps to explain changes of state.

Building on previous learningThe chapter follows on from concepts developed in KS25C Gases, 5D Changes of State, 6C Dissolving, 7D Solidsand Liquids.Could be used in conjunction with 6E as a KS2/3 bridgingunit.

Future learningAll following KS3 and KS4 units depend on thekinetic/particle model developed in this unit.

Common misconceptionsIn this chapter beware of these misconceptions:

◆ Often the simple word ‘stuff’ is clearer to youngerpupils than matter. Matter has several meanings inEnglish.

◆ Be careful to make the distinction between materialand substance. ‘Material’ is often thought to be cloth,and a material such as concrete that pupils think of asone material is a mixture of substances.

◆ Objects are often confused with substances, e.g. glass,drinking glass, glasses, spectacles; a wood and wood;and wax can be thought of as an object.

◆ Breadcrumb misconception: pupils think that thesmallest particle of matter is like making breadcrumbsor crushing up a sugar cube. They think they can be

achieved by grinding up a solid. They think the‘smallest possible particles’ vary in size and shape andare optically visible.

◆ ‘Property’ has other meanings in English, beware.◆ The properties of the particles of a substance are the

same as substances themselves, e.g. copper atoms arered-brown, silver atoms are shiny, water molecules arewobbly liquid, chlorine molecules are yellow-green.

◆ Use the concept of density as ‘heaviness for its size’.Often density is confused with mass, weight orheaviness.

◆ Teach a 1:1:10 ratio of spacing between the particlesin solids, liquids and gases. Many pupils think thatliquids have an intermediate spacing between that ofsolids (touching) and gases (widely separated). Thisratio of spacing results in an approximate ratio ofdensities of 1:1:1/1000 (1-3:1-3:10-3).

◆ Relative particle spacing among solids, liquids andgases (1:1:10) is incorrectly perceived and notgenerally related to the density of the states.

◆ Solids: pupils think of solid particles as having aregular arrangement, but as particles that are notmoving, the concept of vibrations is difficult.

◆ Solids and liquids: pupils think the particles areimmobile, if they do think of them as moving, they donot develop the concept of the particles moving witha range of velocities.

◆ Pupils think the moving particles slow down withtime. They ‘run out of speed’.

◆ Liquids: pupils think liquids are made out of dropletsthat fuse together to make a continuous material.They find it hard to think of liquids as made ofparticles. They have, or course, often been taught toshade in water as a continuous block, so this conceptis hard to break.

◆ Powders can be poured so they are thought to be anintermediate between bulk solids and liquids.

◆ Thick liquids, such as tomato sauce, paste and honey,are thought not to be liquids.

◆ Liquids are always lighter (less dense) than solids.◆ A common misconception is that ‘gases do not exist’ /

‘they are empty space’ / ‘they are nothing’.◆ Air is a good gas, methane burns and smells so it is a

bad gas.◆ Evaporation; the vessel or surface has absorbed the

liquid, in some way it is porous and the liquid soaksin, is a common idea.

◆ Condensation: a common misconception is that‘coldness’ spontaneously generates the water.

◆ Gases are not matter because most are invisible.◆ Gases do not have mass.◆ A ‘thick’ liquid has a higher density than water.◆ Mass and volume, which both describe an ‘amount of

matter’, are the same property.◆ Helium and hot air are the same gas.◆ Expansion of matter is due to expansion of particles

rather than to increased particle spacing.◆ Particles of solids have no motion.

Pupil’s Book A

Chapter 2 Changes

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◆ Materials can only exhibit properties of one state ofmatter.

◆ Melting/freezing and boiling/condensation are oftenunderstood only in terms of water.

Match toNational Curriculum references3.1 Classifying materialsa) how materials can be characterised by melting point,

boiling point and densityb) how the particle theory of matter can be used to

explain the properties of solids, liquids and gases,including changes of state, gas pressure and diffusion

c) that the elements are shown in the periodic table andconsist of atoms, which can be represented bysymbols

d) how elements vary widely in their physical properties,including appearance, state at room temperature,magnetic properties and thermal and electricalconductivity, and how these properties can be used toclassify elements as metals or non-metals

3.2 Changing materialsa) that when physical changes take place, mass is

conservedb) about the variation of solubility with temperature, the

formation of saturated solutions, and the differencesin solubility of solutes in different solvents

c) to relate changes of state to energy transfers

Scheme of Work section7G: Particle model of solids, liquids and gases.

Yearly teaching objectivesDescribe a simple particle model for matter, recognising:◆ the size, arrangement, proximity, attractions and

motion of particles in solids, liquids and gases; therelationship between heating and movement of theparticles.

Use the simple particle model to explain:◆ why solids and liquids are much less compressible

than gases;◆ why heating causes expansion in solids, liquids and

gases;◆ why diffusion occurs in liquids and gases;◆ why air exerts a pressure;◆ why changes of state occur.

Resources providedActivity 2.1 How does water temperature affect how longice takes to melt?Homework 2.1 Carnival people

Activity 2.2 Flick booksHomework 2.2 Particle pictures

Activity 2.3 Measuring densityHomework 2.3 Properties

Activity 2.4 Expansion: five simple experimentsHomework 2.4 Expansion

Activity 2.5 Elastic and plasticHomework 2.5 Stretchy and bendy

Activity 2.6 Making the particles danceHomework 2.6 Always moving and mixing

SuggestionsThinking skills opportunities◆ All of these ideas develop the use of material

modelling techniques.◆ Use of concept mapping.

Key vocabularyboiling; condensation; crystal; density; diffusions;evaporation; evidence; expansion; fibres; freezing; gas;grains; hardness; jelly; liquid; mass; melting; metal;microscope; movement; particles; pressure; property;random; shape; solidifying; squash; syringe;temperature; theory; thermometer; vibrate; volume;solid

AnswersAnswers to questions in Starter Activity1 Solid: ice; flour; ceramic; sugar; wood; wax; plastic;

steel; ice creamLiquid: cooking fat; cooking oil; petrol; water; milk;eggsGas: steam; carbon dioxide; helium; butane

2 Solids have a fixed shapeLiquids have a fixed volumeGases expand to fill any volume

3 Melting: fat, wax, iceBoiling: water, butane, cooking oil

4 It changes shape5 It bubbles and disappears6 Ice, wood, wax, fat, oil, ice cream7 Butane, petrol, cooking oil8 Expansion

Answers to End-of-unit test1 Ice2 Steam/water vapour3 Liquid water has no fixed shape4 Filtering5 Heat it/melt it6 Melting7 The whole surface moves about8 It goes down9 From the pan

10 Condensation11 It mixes12 Diffusion13 The particles move randomly/Brownian motion14 The smell particles diffuse through the air15 Expansion16 It has increased in length17 The particles vibrate more, so they take up more

room18 The air particles are not in contact so they can be

pushed closer together19 The air particles hit the inside of the tyre, creating

pressure20 8 g per cm3

Pupil’s Book A Chapter 2

30 Hodder Science Teacher’s Resource A © 2003 Hodder & Stoughton Educational

Target sheetChapter 2

Tick off the list as you work through Chapter 2 when you are happythat you understand the following:

YTO Target Tick

✓ I can recognise if a substance is a solid,

liquid or gas.

✓ I can list the differences between solids,

liquids and gases.

I can use a Bunsen burner safely.

I can present my ideas to the class using a

poster.

✓ I can explain the different types of

arrangement of particles in solids, liquids

and gases.

✓ I know all matter is made of particles too

small to see with the naked eye.

✓ I can talk about the squashiness of gases

using a particle explanation.

✓ I know that particles in matter are moving

all the time.

✓ I can describe the different movements of

particles in solids, liquids and gases.

✓ I can talk about expansion, diffusion and

gas pressure, using a particle movement

explanation.

I can calculate density (mass ÷ volume for

simple objects).

Hodder Science Teacher’s Resource A © 2003 Hodder & Stoughton Educational 31

End-of-unit testChapter 2

The numbers at the end of questions indicate the level.

1 What is water called when it is a solid? (level 3)

2 What is water called when it is a gas? (level 3)

3 What is the difference between solid water and liquidwater? (level 3)

4 Either explain or draw how you can separate a solid from aliquid. (level 4)

5 You have a lump of solid wax. How can you turn it into aliquid? (level 3)

6 What is it called when a solid turns into a liquid? (level 3)

7 You have put a pan of water to heat on the cooker. How can youtell when the water is boiling? (level 4)

8 If you leave the pan for several minutes, what happens to thelevel of the water? (level 4)

9 After a while, water drops are running down the kitchenwindow. Where do you think this water came from? (level 4)

10 What is the name of the process that causes the water to appearon the window? (level 4)

11 When blackcurrant drink is mixed with water it forms a layer atthe bottom. What happens if you leave it withoutstirring? (level 4)

12 What is the mixing process described in Question 11called? (level 4)

13 What special characteristic of liquids makes this mixingpossible? (level 5)

14 Explain how the smell of freshly cut onions can spread across aroom. (level 5)

15 On a hot summer’s day, telephone lines to houses ‘sag’ morethan normal. What is this called? (level 4)

16 Explain what has happened to the metal telephone wire. (level 5)

17 Explain or draw what has happened to the movements of theparticles in the wire. (level 6)

18 Why can lots of air get squashed into a smaller space when abicycle tyre is pumped up? (level 5)

19 Why does a bicycle tyre feel hard when it is pumped upproperly? (level 6)

20 A small steel bolt has a mass of 56 g and a volume of 7 cm3. Whatis its density? (level 6)

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RationaleLearning outcomesMost pupils will be able to draw and describe particles insolids, liquids and gases in terms of movement andproximity of the particles.

The faster pupils will be able to explain the propertiesof solids, liquids and gases using kinetic theory.

Those who progress less quickly will know about thedifference between solids, liquids and gases in terms ofthe kinetic theory.

Lesson plan1 hour/lesson

Spread 2.1 uses the carnival people analogy to describestates of matter.

Suggested starters◆ Investigate what pupils know from KS2 by asking

questions about the differences between solids,liquids and gases.

◆ Use the chapter starter on page 13 to act as a pre testof KS2 material.

◆ Discuss the illustration on page 13.◆ Answer the questions as a class verbally, or

individually in their books.

Main activities◆ Activity 2.1 How does water temperature affect how

long ice takes to melt: an investigation into the affectof temperature on ice melting.

◆ Work through Spread 2.1 in Book A.◆ Give pupils a range of materials to classify as solids,

liquids or gases, including some which are difficult toclassify.

◆ Ask pupils to explain their ideas in terms of theparticles that make up the materials.

◆ Compete the questions and remember box on page 15.

Suggested finishersFinisher A States of Matter Traffic Lights activity. Giveeach pupil three small pieces of coloured card about 10cm square (one red, one yellow or orange, one green).These are used to signal their answers: red means SOLID;yellow or orange means LIQUID; green means GAS. NBthis activity starts easily – but then goes onto somematerials that are much harder to classify. Pupils mayneed extra cards or to answer in pairs as some of thequestions are mixtures of two states.

The game follows this sequence:◆ Read the question.◆ Allow a short period of time for pupils to consider

their answer.◆ Count ‘1,2,3 show your cards!’◆ Pupils all hold up one of their cards at the same time.

HomeworkHomework 2.1 Carnival people: A series of questionsabout states of matter.

2.1 Carnival people


Technician’s notesEquipment Quantity/group

Beakers (250 cm3 or 400 cm3; 3plastic is safer than glass)

Bench mat, Bunsen burner, 1gauze, tripod*

Matches/spills 1

Thermometer† 1–2

Measuring cylinder (plastic 1100 cm3)

Stop clock 1

Ice cubes‡ 3–4

Cold water¶ 100 cm3

Eye protection 1 pair/student

SuggestionsLiteracyThe descriptions of what it is like to be in a packedstadium with seating, Christmas shopping crowd (seeQ4), a disco or running in a space such as a gym or hallgive rise to good literacy and oracy activities with lots ofopportunities to rehearse target vocabulary.

NumeracyCalculations of solid volumes from dimensions.

Calculation of numbers of seats in, for example, a block ofseats that goes 1–25 and A to H.

Key skillsGroup work on posters and displays of drawings. Goodcommunications skills practice.

Cover friendly rating2 star (0 stars for role play in hall).

Cross curricular linksMaths (volume and area calculations), Drama (kinetictheory modelling)

Experimental notes* Alternatively, use electric thermostatically-controlledwaterbaths set at different temperatures.† �10°C to 110°C, 150 mm non-toxic fill, fitted with ananti-roll device. A suitable anti-roll device for athermometer is the plastic packaging tip or a child’s pengrip. If very accurate measurements are required,mercury-filled thermometers will have to be used.‡ Have sufficient available in the freezer for 3–4 icecubes/beaker + extras for repeats.¶ Have 1 litre plastic containers in the fridge (4°C) readyfor use. Place in a bath of crushed ice. To crush ice, makesmall ice cubes, place in a strong plastic bag and wrap in atea towel. Using either a hammer or a rolling pin, crushthe ice. Wear eye protection.

33


Answers1 & 2 Questions require the pupils to draw pictures ofpeople sitting close together. If possible, do a mock-up ofthis situation showing knees close to heads in front andshoulders touching. Emphasise that no more people canget fitted into spaces, and that the people are in neatrows and columns.3 Emphasise that when people are in a crowd they are incontact with each other, but there are no neat lines orranks of people.

4 This is a possible literacy and oracy activity. Could beused as an alternative homework.5, 6, 7 All of these questions can be best used after asolid/liquid/gas role play in a school hall. Videoing theperformance from the stage makes a very useful resourcefor later lessons.

Match toNational Curriculum reference3.1 a and b


Activity sheet

To make a cold drink very cold we add ice to it. On a summer day abottle of drink can be quite warm (or a lot colder if kept in thefridge). Explain here why ice melts when it is put into a drink (orinto water).

You are going to put ice into water at three different temperatures.Make a prediction about the different times it might take the ice tomelt.

What apparatus will you need to use?

To make the investigation a fair test you have to keep the amountsthe same. Complete these sentences.

The container I will use each time will be

The amount of water I will use each time will be

The amount of ice I will use each time will be

In this table record your results:

Chapter 2

2.1 How does water temperature affecthow long ice takes to melt?

Temperature of water

Time ice took to melt

Write what you saw happen here.

Explain why there was this difference.

Homework sheetChapter 2

2.1 Carnival people

1 Copy the passage below and use these words to complete thesentences:

gas volume liquid squashy same solid shape flow

There are three states of matter ______, ______ and ______.Solids and liquids stay the same ______ but gases are ______ andcan be squeezed into a smaller volume.Solids always stay the ______ shape.Liquids take the ______ of the container they are in.Both liquids and gases can be made to ______ along a pipe.

2 a) Look at the picture of Mandy’s cafe below.

Solid Liquid Gas

b) What three materials are turning from a solid to a liquid?c) Look at your answers for part b). Explain what each materiallooks like when it is solid and when it is liquid.d) Make another ‘Solid, Liquid, Gas’ table like the one used inpart a). Put these words into the table where you think they fit.Some words will fit into two different parts of the table.

squashy hard wet flows heavy escapes rigid sloppy smell

3 Copy and complete the table below.Do not use ‘water’ as a liquid – it is too easy!

Place Solid Liquid Gas

kitchen (to make pans) (for washing dishes) (comes from the kettle)

bathroom (for washing) (for hair washing) (for underarm use)

camping (for tent pegs) (to start barbecue) (to fuel a camping light)

school lab (for benches) (to react with metals) (for Bunsen burners)

technology (to heat and bend (to make metal (for welding)room into shape) slippery)

Copy the table below and put three substances from the picturein each of the columns.


RationaleLearning outcomesMost pupils will be able to draw and describe particles insolids, liquids and gases in terms of movement andproximity of the particles.

The faster pupils will be able to explain the propertiesof solids, liquids and gases using kinetic theory.

Those who progress less quickly will know about thedifference between solids, liquids and gases in terms ofthe kinetic theory.


Spread 2.2: uses the carnival people model to explain theproperties of solids, liquids and gases.

Suggested starters◆ Start with imagination exercises. Ask the pupils to

describe Christmas, holiday, lunchtime at school,doing a French lesson. Focus in on the idea that allthoughts are ‘images’ held in the head rather thanwords and sentences. Use the text and discussion toimprove on the imagination of the ‘Carnival model’.

◆ Activity 2.2a Flick books: Producing flick books of howsolids, liquids and particles behave. These pages canbe enlarged to A3 and copied onto card.

◆ Apply the ideas to explaining simple properties ofmatter as in the text.

Main activitiesActivity 2.2b Carnival role-play: Get pupils to dramatisethe movement of particles in solids, liquids and gases.Video them performing a role-play. Pupils can thenrecord the ideas in a manner suitable to themselves. A fullset of pupils briefing cards are provided. The focus of thisactivity is to imagine what will happen as the solid/ liquid/gas gets hotter. ◆ Divide the class into three groups, one for each of

solids, liquids and gases. ◆ Give three or four copies of the cards to each group

to brief them all in the same way. (See briefing onactivity sheet ‘When you get hot’).

◆ Get the groups to plan their performance (this shouldonly take 5 minutes).

◆ When they are ready ask them to perform in turn forabout 5 minutes.

◆ You could record their performance with a digitalvideo or webcam and make the pictures available onthe school intranet.

◆ At the end get the pupils to consider the extraquestions, if time permits.

◆ On a subsequent occasion, swap the groups so eachperson gets a turn at other ‘particle modelperformances’.

Suggested finishersWork through the questions and remember box on pages16 and 17.

HomeworkHomework 2.2 Particle pictures: Pupils are asked to drawpictures of solids, liquids and gases.

2.2 A closer look at carnival people


SuggestionsLiteracyThis chapter and activity is mainly about visualisation ofwhat particle movements are like. This givesopportunities for numeracy and oracy in describing whatthe different movements look like.

NumeracyCalculate or count the different numbers of particles ineach flick book frame or particle picture. Introduce theidea of particles per unit volume and compare this forsolids, liquids and gases.

ICTThere are several simulations available that animate themovements of particles. The best of these is States of

Matter from New Media.

Cover friendly rating3 star (and the flick book practical activity is possible withnon-science staff)

Cross curricular linksArt (pictures showing particle movements, particularlythose using the Carnival People idea, would make a goodlink with art activities showing movement).

Answers1 Solids have a fixed shape.2 Solids can’t be compressed.3 Solids have a fixed volume.4 Solids don’t mix.5 Liquids can’t be compressed.6 Liquids have no fixed shape.7 Liquids can mix (diffuse).8 Gases exert pressure on the walls of their container.9 Gases have no fixed volume.

Match toNational Curriculum reference3.1 b and 3.2 a.

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Activity sheet

When Disney or Warner Brothers make ananimated cartoon, they create millions ofpictures and show them to you one afteranother.

A simple way of making an animation is tomake a ‘flick book’.

So try this

Make an animation of how the particlesbehave in solids, liquids and gases.

Chapter 2

Write a description of what you see.

Explain how your animation shows that:1 solids stay the same shape2 liquids can’t be squashed much

smaller3 gases can be squashed into a smaller

space4 gas pressure pushes against the walls

of the container

2.2a Flick books

liquid1

liquid3

liquid5

liquid7

liquid2

liquid4

liquid6

liquid8

gas1

gas2


Activity sheetChapter 2

2.2a Flick books (continued)

gas7

gas8

solid1

solid3

solid2

solid4

solid5

solid6

solid7

solid8

gas3

gas5

gas4

gas6



2.2b Carnival role play

Briefing: When you get hotYou are going to imagine that you are one of the particles in a solid,liquid or gas. When you get ‘extra energy’ as a particle you start tomove more and more quickly. Think about how this affects thedifferent states of matter.

Carnival people role play cards

Hotter solidYour group is to act the part of a block of solid matter beingheated up. Each person must take up a fixed position with theirfeet staying in the same place. All of you must be close together,nearly touching.But you are never completely still. You move to and fro, bend atthe knees a little and straighten again, forward and back. Imaginethe music is getting you more and more excited. Imagine and actout what happens to your movements. You move up and down,side to side, faster and faster. But don’t move from your place!You must remain in the same place, so that your solid stays thesame shape.

You only have 5 minutes to practise and get your performanceright.

Hotter liquidYour group is going to act the part of a drop of liquid. All of youhave to stay in contact all the time, but continually moving andswapping places. You can duck under each other’s arms, slideover the ducked people’s heads, squeeze in between others arms.All the time look like rolling moving particles, using your arms tomaintain contact by sliding over each other. Now the music andenergy are getting you excited; as time goes on make the speed ofyour movement steadily increase. You all have to remain incontact so that your drop of liquid stays the same volume.

You have only 5 minutes to practise and get your performanceright.



Extra questions for fast workers1 Imagine that as they get hotter your solid particles move faster

and faster, more and more. Eventually they MUST break awayfrom their fixed position. Then the solid structure with its shapewill be lost. This is melting. Describe what happens to theparticles during this process.

2 Imagine that as they get even hotter the liquid particles movepast each other, faster and faster. Eventually as they move fasterthey MUST lose contact with each other and spread out in space.The fixed volume of the liquid droplet will be lost. This isboiling. Describe what happens to the particles during thisprocess.

3 Imagine the gas particles rushing about faster and faster as theyget hotter. They hit the sides of the container faster and faster,causing more and more force. Eventually the sides of thecontainer cannot resist the force any longer and the containerwill burst. Describe what happens to the particles before, duringand after the container bursts. (Think about a balloon burstingwhen it gets too hot).

Gas pressureYour group is going to act the part of a pocket of gas. You shouldall be separate from each other and travelling steadily in straightlines. You keep going in straight lines until you bump into thesides of the ‘container’ or another gas particle (BE CAREFUL – wedon’t want injured gas particles!). Gas particles don’t keeptogether; they will spread out to fill any space they are in. They aremoving all the time, but only change direction when they bumpinto something. When you hit the sides of the ‘container’ thisproduces a push on the inside. When you hit an outside wall say‘air pressure’ loudly. This force only happens when you changedirection.

Start slowly, only walking in pigeon steps. Now the music andenergy make you move faster. Soon you are walking, then dancingalong. As all you gas particles go faster note what happens to thenumber of times ‘air pressure’ gets said.

You have only 5 minutes to plan and prepare your performance.

2.2b Carnival role play (continued)



2.2 Particle pictures

Use a 1p coin to help you draw theparticles.

The particles in a solid are all in fixedpositions. They all touch each other. Theymake a really regular pattern.

Draw the particles in a solid here – fill thebox.

The particles in a liquid are squashed

together like people in a crowd. They arein a random jumble with no pattern.

Draw the particles in a liquid here – fillthe box.

The particles in a gas are spaced far

apart. They do not touch each other.

Draw the particles in a gas here – fill thebox.

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RationaleLearning outcomesMost pupils will◆ learn how to relate particle forces and hardness◆ know how to calculate density given the equation.

The faster pupils will be able to calculate◆ density for any object◆ the volume of a regular object.

Those who progress less quickly will◆ know that ‘heaviness for its size’ is called density◆ have calculated density for some objects.


Spread 2.3 discusses the concepts of hardness anddensity.

Suggested startersLesson starter A Particle loop is a question loop activity.These pages can be enlarged to A3.

Main activities◆ Ask pupils to describe what activities they have done

in D&T that involve cutting and shaping materials. Askpupils to imagine why a saw cuts wood. Ask pupilswhat would happen to the teeth of the saw if theblade was wood and the material being cut was metal.

◆ Use the ‘mental microscope’ to get pupils to focus inon why particles in wood are easier to pull apart thanparticles in steel.

◆ Ask pupils ‘does the wood get destroyed like when itgets burnt?’

◆ Extend the idea to the ‘heaviness for its size’ of theparticles involved. Calculators will be needed fordensity calculations. Note: Density units used aregrams per cubic centimetre in calculations for KS3pupils.

◆ Activity 2.3 Measuring density can be used toconsolidate these ideas. A practical activity thatmeasures volume and density of a variety of materials.

Suggested finisher◆ Finisher B Materials A to Z: Recaps the ideas and

vocabulary discussed so far with a quick A to Z quiz,while also revising essential pre knowledge from KS2as well. Both a question and a question and answersheet are provided. Photocopy the question sheet oruse as a quiz. Do the activity against the clock to findthe highest score. The questions are reasonablydemanding.

◆ You could get your own pupils to generate their ownquizzes. You could also use the quiz as a tutor timeactivity.

HomeworkHomework 2.3 Properties: Consolidates ideas about theproperties of materials.

2.3 Hard lessons


SuggestionsLiteracyThere is a reasonable amount of reading and vocabularyin this chapter.

NumeracyThis chapter and activity are very numeracy heavy.Calculators will be needed by all but the most able pupils.Pupils will need to be able to rearrange formulae.

ICTUse of a spreadsheet to calculate density is a relativelysimple exercise.

Sc1 Ideas and evidenceThere is a possible opportunity for an investigation intothe hardness of materials, but this unit is rather contentheavy and time constraints make it difficult to carry out.

Cover friendly rating3 star (textbook) and 1 star (activity)

Cross curricular linksMaths (calculations), Technology (understanding thehardness of resistant materials, wear and tear rating)


Mixed blocks:*aluminium, steel, marble, 1 setwood, slate, wax, lead, brass, polystyrene, glass, Perspex

Eureka can (also known as a 1–2/classdisplacement vessel)†

Balance (with an accuracy 1–2/classof 0.1 g if possible)

Measuring cylinder (100 cm3; 1–2/classplastic)

Rulers 1–2

Experimental notes* This is available from laboratory suppliers as ‘SolidMaterials Kit’. At the end of the practical check that: thesteel is dry, the wax has not been gouged, the polystyrenehas not been picked. To repair the wax, gently heat apalette knife and smooth out the surface. Wrap the steelin greased paper for storage.† If a Eureka can is not available, a 250 cm3 measuringcylinder half filled with water could be used.

43


Answers1 The metal particles in the saw can pull the wood

particles apart, so they must be held together morestrongly.

2 Soap – least hard, candle wax, dry clay, brick, stone,steel drill – most hard

5 Wood (desk) 0.5 g/cm3

Steel 7.7 g/cm3

Wood (chopping board) 0.5 g/cm3

Lead 11.0 g/cm3

Steel 7.7 g/cm3

Marble 180 cm3

Perspex 60 grams6 Knives and metal things feel heaviest for their size.7 The desk is heavier but it has a much bigger volume.

It is not as ‘heavy for its size’ as water, so it floats.8 Lead – most dense, steel, marble, perspex, wood –

least dense

Answers to finisher activity BAbsorbent, boiling, clay, density, elastic, fluid, granite.heavy, ice, jug, kettle, liquid, melts, natural, opaque,plastic, quartz, rubber, squash, transparent, unbreakable,vapour, warmest, xenon, yellow, zinc.

Match toNational Curriculum reference3.1 a and d.


Activity sheet

Density is the proper name for ‘heaviness for its size’.

You calculate density like this:

Density is measured in grams per cubic centimetre. The short way of writing this is g cm�3 or g/cm3.

MassMeasure mass using a top pan balance.

Volume: blocksMeasure volume by measuring the three sides of the block and doing this sum:

Volume: lumpsMeasure the volume by putting the lump in a can with a spout. The lump displaces its own volume of water. Measure the waterdisplaced in a measuring cylinder.

DensityWhen you calculate the density don’t writedown all the numbers on the calculator.Your measurements are less accurate thanthat. Round off your answer to two figures.

Copy and complete the table below as much as you can. You may not have all these objects so your teacher will give you the data.

Chapter 2

2.3 Measuring density

Density � Mass (g) ÷ Volume (cm3)

Volume (cm3) � Length (cm) � Width (cm) � Height (cm)

Material Mass (g) Volume (cm3) Density (g/cm3)

aluminium

steel

marble (white stone)

wood

slate

wax

lead

brass

polystyrene foam

glass

perspex

catch the water displaced by the object ina beaker, then measure the volume in a

measuring cylinder

eureka can

100 cm3

beakerlump of rock



2.3 Properties

Use in the home Metal Reason why it is used

1 kitchen foil aluminium can be rolled very thin and still be strong

2 solder

3 copper

4 steel

5 gold

6 lead

Property Object using that property

flexible 1 clothes peg spring23

wear resistant 1 knife blade23

hard 123

can be shaped easily 123

waterproof or airtight 1 gas cylinder (camping)23

2 Steel is the most commonly usedmetal in our lives. Here is a list ofthe properties of steel. Add to thelist three examples of objects thatuse each property. Some have beendone for you.

3 Hard materials can be used to cutsofter materials. Diamond is harderthan glass, so diamond can be usedto cut glass.Make a list of examples where ahard material is used to cut a softerone.

Property Object that uses this property Another material that could be used

light garden furniture wood

hard wearing

coloured

heat insulator

electrical insulator

does not rot

1 Complete the table with the namesof five things made of metal andused in the home. One example hasbeen done for you. Think of thingsmade from different metals eachtime if you can.

4 The diagram shows an electric kettle and lead. Make a list of the parts shown that are made from heat insulators. Make a list of the parts shown that are made fromelectrical insulators.

5 a) Copy and complete this table aboutthe properties of plastic objects. Thefirst one has been done for you.

switch (plastic)

handle (plastic)

flex (insulation)

plug

wires (in lead)

kettle body(plastic)

element

pins

b) For each one write a sentenceexplaining why plastic is better thanthe alternative material.

46


RationaleLearning outcomesMost pupils will◆ know that most materials expand when heated◆ learn that expansion produces very large forces,

particularly in solids◆ know that bases expand more than liquids or solids.

The faster pupils will◆ learn that ice is an anomalous substance that expands

on freezing◆ know that liquids expand more than solids.

Those who progress less quickly will know that◆ heating causes expansion◆ some materials expand more than others.


Spread 2.4 introduces the idea of solids, liquids and gasesexpanding.

Suggested startersStarter B Particles bingo: A fun, snappy starter activityusing a key word bingo. These pages can be enlarged to A3.

Main activitiesActivity 2.4 Expansion: five simple experiments: Standardlaboratory practical tasks investigating expansion that canbe used either as a guided teacher demonstration or as acircus of activities.

If this lesson is to be included early in a Year 7 scheme ofwork, it makes a good opportunity to introduce pupils tolaboratory safety. Use the hazard and safety sheet on pagexx. For each practical task ask the pupils to identify thehazard and suggest how to limit the hazard and how theywould ensure safe working.

In this circus you will need to give each working group(pair) a fresh ball and ring, a fresh bar and gauge andpossibly a fresh bi-metallic strip each time, as they remainhot. This causes a particular hazard with plastic trays. Ifthese pieces of equipment are placed back in plastic traysthey can melt the plastic disastrously. A safer alternative isto place the ball and ring, bar and gauge and bi-metallicstrip in a container of water after use.

Each of these practicals take about 3 minutes. Pupilsshould then spend five minutes writing or drawing aparticle model explanation for what they have seenhappen. Be careful of pupils suggesting that particles getbigger when they get hotter!

Use the carnival people model and ask pupils whathappens to the spectators or crowd when people getmore excited. People don’t swell up, they just get moreactive. Use this to explain expansion.

If there is time, extend the air thermometer practical toputting ice point and steam point calibrations on thethermometer.

Suggested finishersFinisher C States of matter sequencing.

HomeworkHomework 2.4 Expansion can be used to consolidateideas.

SuggestionsLiteracyThere is a considerable amount of reading and newvocabulary in this spread. Make sure the new vocabularyis learnt and spelt correctly. Use the Read – Say – Cover –Write method.

NumeracyNumeracy activities on expansion are possible, but quitedifficult. Coefficient of linear expansion data are to befound in older GCE textbooks.

ICTSearch the Internet for uses of expansion in industry.

Sc1 Ideas and evidenceInvestigate the amount of expansion of water as itsolidifies. Put a plastic syringe part full of water in afreezer. Record the volume before and after freezing.Investigate the amount of ‘bend’ in a bimetallic strip atdifferent temperatures.

Key skillsExpansion activities develop group working and co-operation skills.

Cover friendly rating4 star (textbook), 0 star (activity)

Cross curricular linksTechnology (use of expansion in engineering. Allowingfor expansion in the design of components that get hot).

2.4 Expansion

47


Experimental notes* Air thermometer: If a round-bottomed flask is notavailable, a good alternative is a plastic pop bottle with aminimum volume of 500 cm3. A size 21 bung fits this sizeof bottle. Using 5 mm diameter capillary tube, cut a piece300 mm long and flame the ends to remove any sharpedges. Insert the capillary tube into the bung from thewide part so that the tube does not protrude through thenarrow part. Follow the procedure for inserting tubinginto bungs in CLEAPSS Laboratory Handbook (page 932onwards). Set up the apparatus as in the diagram on theActivity Sheet.† To make coloured water, add food dye to the volume ofwater needed until the desired depth of colour isobtained.‡ Water thermometer: Cut a piece of 5 mm diametercapillary tube at least 300 mm long and flame the ends toremove any sharp edges. Insert the capillary tube into thebung from the wide part so that the tube does notprotrude through the narrow part. Follow the procedurefor inserting tubing into bungs in CLEAPSS LaboratoryHandbook (page 932 onwards). Insert the bung into theboiling tube, ensuring that the capillary tube does not gointo the coloured liquid. When the bung has been putinto the tube, VERY CAREFULLY push the capillary tubedown 2–3 cm into the liquid. Set up the apparatus asshown in the diagram on the Activity Sheet.

Answers1 The level of water will rise up the tube.2 In the freezer, the water column inside the tube will

freeze in one place. So it will not move as thetemperature changes.

Match toNational Curriculum references3.1 b and 3.2 a


Ball and ring apparatus 1

Bar and gauge apparatus 1

Bimetallic strip 1

Bunsen burner, bench mat, 1tripod

Matches/spills 1

For air thermometer:*

Round-bottomed flask (500 cm3 minimum) 1

Beaker (250 cm3) 1

Capillary tube 1

Rubber bung (dependent 1on size of flask. Size 31 one hole for a 500 cm3

flask)

Coloured water† 100 cm3

Retort stand, boss head, clamp

For water thermometer:‡

Test tube (Pyrex or equivalent) 1

Capillary tube 1

Rubber bung (size 21 hole) 1

Coloured water† 40 cm3

Retort stand, boss head, 1clamp

Beaker (400 cm3; plastic is 1safer than glass)

Bunsen burner, bench mat, 1tripod

Marker pen – permanent 1

Ruler (30 cm length required) 1



Activity sheet

Put hot objects carefully on a heat-

proof mat. Do NOT touch the ball

when heated.

Ball and ringTry and see if the brass ball passesthrough the ring before heating. Now heatthe ball over a Bunsen flame. Note: ONLYheat the ball part of the apparatus.

Will the ball pass through the ring after ithas been heated? Explain your answer.

Bar and gaugeTry the bar in the hole and across the gap.

Heat the bar in a Bunsen flame. Try it inthe hole and the gap again.

Explain what has happened to the bar.

Bimetallic stripHeat a bimetallic strip in a Bunsen flamethen let it cool on a heat-proof mat.Explain what you see happen.

Chapter 2

Air thermometerSet up the apparatus as shown in thediagram.

Explain what you see happening. Try touse scientific words to explain what youhave observed.

Water thermometerSet up the apparatus shown in thediagram. It works in the same way as abought thermometer.

Measure how much the level has changed.

Explain what you see happening. Try touse scientific words to explain what youhave observed.

How would you make an accurate scaleon your thermometer to measure degreesCelsius?

2.4 Expansion: five simple experiments

Write your answers in your exercise book.

round-bottomed flask

level of coloured waterclamp stand

coloured water

clamp stand

glass tube

bung

beaker of watergauze

tripod

test tube of coloured water

bar

gauge



2.4 Expansion

1 Say whether each of these things is an example of expansion orcontraction, and whether or not it is a useful effect.a) Milk freezes on the doorstep and pushes the foil top off.b) As it gets colder, the mercury level in a thermometer drops.c) A boiling liquid is poured into a cold glass and makes it crack.d) A railway wagon wheel rim is heated very strongly beforebeing fitted onto the wheel.

2 Look at the diagram of the thermostat. Thermostats are used tocontrol the temperature of a room. Because brass expands morethan steel when it is heated, it makes the bimetallic strip bendupwards and the contacts move apart.

1 AutumnSmall crack appears in rock.Water gets into crack.

2 WinterWater in crack freezes and expands. Thisprocess widens the crack.

3 Next SpringEarth and seeds blow into the wider crackin the rock.

4 Next SummerPlants grow and their roots push on therocks, making the crack even wider.

5 Next Autumn/WinterEven more water gets into the bigger crackand freezes. Eventually a lump of rock isbroken off.

a) Explain how the heating circuit gets turned off when the roomis warm.b) Explain why the heater gets turned on again when the roomgets colder.c) Explain why you would not put a thermostat like this near awindow.

3 Copy the table below. Draw pictures to illustrate each stage inthe weathering process.

circuit in

circuit out

bimetallic stripiron

brasscontacts

adjusterscrew

fixed metalblock

fixed metalblock

50

RationaleLearning outcomesMost pupils will know that◆ gases are stretchy, and solids and liquids are not◆ materials stretch evenly up to their elastic limit.

The faster pupils will know that◆ springs and rubber bands behave differently after their

elastic limit◆ plastic is the opposite term to elastic.

Those who progress less quickly will know that◆ all substances have different elastic properties◆ graphs can be drawn to represent stretching.


Spread 2.5 the idea of solids, liquids and gases stretchingand bending is introduced.

Suggested starterTo change the style of starters and bookwork spread 2.5could be tackled verbally. This gives increased time forpractical work.

Using the pictures as prompts, ask the pupils to describetheir own experiences◆ of flexible materials generally◆ of snapping rubber bands◆ of fixing loads with elastic straps◆ of dentists filling teeth◆ of ball ponds and crash mats◆ of swimming pools and belly flops

Discuss these experiences to bring out ideas of which arethe squashiest materials, which materials are elastic(regain their shape) and which are plastic (stay in theshape they have become).

Main activitiesActivity 2.5 Elastic and plastic: this is a good opportunityto practice Sc1 skills. Research has shown that mostpupils find planning, not evaluation, to be the hardest ofskills to master effectively. The activity sheet outlines apractical that can be planned at least in part by the pupils.The activity obtains results, graphs them and looks for apattern. So further investigative skills are addressed.

The emphasis of this activity is on planning. Get thepupils to think through the steps they will need to:◆ select materials to test◆ select apparatus and set it up◆ make sure everything is done safely (use the hazard

and safety sheet on page xx)◆ make trial runs for readings◆ select a range of readings to take◆ repeat readings for accuracy◆ calculate the length/extension of the elastic material.

2.5 Stretchy and bendyTo assist and speed up the plotting of graphs, photocopygraph paper with these items marked:◆ Title: Stretchy materials graph◆ X-axis: 0 to 10 N in 1 N steps

axis marked ‘Force/ N’◆ Y-axis: 0 to 40 cm in 5 cm steps

axis marked ‘Length/cm’◆ Space for their name and the date

Attention should be paid to evaluation – this can be amechanism for learning about planning by improving theinvestigation.

Suggested finishersCopy the remember box paragraph on page 23.

HomeworkAnswer the questions on page 23.

Suggestions

LiteracyThere are good visualisation and explaining activities inthe questions that can be used for literacy and oracywork. There is extensive target vocabulary to learn.

NumeracyGraphs are used in the practical activity. Pupils may needto be given scales and axes to use. Particularly pupils willneed to be taught not to join the dots as a matter ofcourse. This is a line of best fit graph.

Sc1 Ideas and evidenceAs stated above, the practical activity used here is anexcellent introduction to Sc1 experimental skills.

Key skillsPractical work requires development of group work skills.

Cover friendly rating4 star (textbook), 1 star (activity)

Cross curricular linksMaths (graph plotting), Technology (properties ofmaterials)


51


Experimental notes* Equal lengths if possible, have spares available.† These are available from laboratory suppliers with brasseyelets. Alternatively, textile elastic can be bought andloops tied at each end.‡ Tie a loop at each end by looping the wire round theretort stand bar and twisting the ends together, ensuringthat there are no sharp points protruding.

¶ Set up the metre rule on the clamp stand using two ofthe clamps so that the metre rule hangs over the edge ofthe bench. Set the other clamp so that the lowest part isin line with the zero of the metre rule. Put a heavy mass(5 kg) onto the base of the retort stand to help to stabilisethe apparatus.

Advice on investigationBoxes filled with crumpled paper should be placedunderneath the masses to catch them safely when theyfall.

Answers1 If the repair has different stretchiness, it would tear

away from the cloth it was sewn onto.2 Pictures should show wood particles as long fibres

and rubber particles like a concertina.4 It would hurt the pole vaulter more if the mat was

filled with water, as water is less squashable than air,making the impact of the pole vaulter harder. Thiswould be better than landing on sand.



Rubber bands* 1 narrow, 1 broad

Textile elastic (elastic cord 1type)†

Copper wire (20–50 swg)‡ 1 piece

Expendable spring (20 mm 1length)

Mass hanger (50–100 g) 1

Masses (50–100 g) 4–5

Metre rule 1

Retort stand¶ 1

Boss head, clamp and 5 kg mass 3



Activity sheet

Elastic means stretchy, but it means more than that. Elastic materialsstretch, twist or bend and then return to exactly their original shapewhen left alone.

Plastic has come to mean ‘made from man-made material’, but theword has another meaning which is an OPPOSITE of elastic. If amaterial is stretched and then stays exactly in its new shape, then it issaid to be plastic.

Comparing stretchiness★ Get two pieces of elastic material to compare. Some examples of

elastic materials you could test are given below:– thin rubber band– thick rubber band– textile elastic– thin copper wire (tie a loop at each end)– short spring

★ Make your test fair by using the same set of masses and the sameapparatus for your two investigations.

★ Use the metre rule to take readings accurate to the nearestmillimetre.

★ Decide how to make the comparison between the two materials. ★ Now write down exactly what you are going to do.★ Make a prediction about the difference in stretchiness between the

materials. ★ Explain your prediction using scientific words.★ Hang your material being investigated from a clamp stand.★ Use a metre rule as a scale.★ Add masses to the material and record the changes against the

scale.★ Fill in a table like this for EACH MATERIAL.

Chapter 2

2.5 Elastic and plastic

Type of material Weight hung on Reading on metre rulermaterial Top Bottom Length100 g � 1.0 N (top – bottom)

1.0 N (100 g)2.0 N (200 g)etc.

★ Draw a graph or chart of your results.★ Explain what you found out about the difference in the

stretchiness of the materials.



2.5 Stretchy and bendy

1 Copy and complete the table below using the words from thelist.

electrical conductor dissolves grease ropes car bodies wires inner tube for tyre washing clothes coloured

airtight flexible hard wearing decorating cloth

Material Property Use

rubber

nylon

dyes

steel

copper

soap

2 Complete these sentences about materials. Use the names ofdifferent materials.

______ and plastic are used for doors because they are easilyshaped. ______ and ______ are used for walls because they arenot easily squashed. ______ and ______ are used for windowsbecause they are see-through. ______ is another word for see-through. ______, ______ and ______ are used to cover the wallsof houses because they keep the rain out. This property is calledbeing ______.

3 The table below gives the sequence of how an air bag in a carworks. Complete the table by matching the explanations with whathappens. Explanations are shown in the boxes below the table.

What happens during the accident Explanation

Air bag inflates from small bottle in steering wheel

Head travels forward and hits air bag

Air in bag squashes and slows head down

Gas in air bag leaks out rapidly

Car goes to garage to have air bag replaced

Gas cannot easily be put back into air supplybottle

Gas is springy. This happens to prevent thehead being pushed out of the air bag again

Gas can be compressed, so a lot of gas (50 litres) is stored in a small volume

In an accident, the driver can be damagedbecause the seat belt does not stop his head

moving

Gas is squashy – it is squashed as the head hitsthe bag

54

RationaleLearning outcomesMost pupils will know◆ what diffusion means in particle movement terms◆ that diffusion works for liquids and gases but not

solids.

The faster pupils will be able to◆ describe the ‘smoke cell’ experiment and explain what

they see◆ explain diffusion in gases and liquids.

Those who progress less quickly will◆ have seen diffusion effects◆ know what diffusion means.

Possible teaching strategiesThe blackcurrant squash/water demo can take more thana lesson to develop mixing – so this may need to beobserved over a longer period of time.

The practical activity requires some investigation andpractice beforehand. It needs group co-operation – oneto rotate the hexagonal stick and the other to support thegas jar.

Lesson plan2 hours/lessons

Spread 2.6 discusses Brownian motion and diffusion.

Suggested starters◆ Set up smoke cells and microscopes at the start of the

lesson (see page 24). It may take time for all pupils tocatch on to what they are actually trying to see. Theobvious can sometimes be missed and the swirlingblobs of smoke particles can be elusive to 11-year-oldeyesight. One possible misconception is that smokeparticles are a gas. They are small droplets of liquid orspecks of solid that are too light to settle due togravity.

◆ Recap the learning objectives from the whole of theunit using the Chapter 2 Targets sheet. Get the pupilsto stick the completed targets sheet into their booksas a record of what they have learnt.

Main activities1 Activity 2.6 Making the particles dance: A practical

activity that requires some investigation and practicebeforehand. It needs group co-operation – one to rotatethe hexagonal stick and the other to support the gas jar.

2 Return to the blackcurrant squash/waterdemonstration. Discuss the results as a class.

Then ask the pupils to complete the end of unit testor key ideas test. In addition test material is to befound in the Hodder Science Assessment Pack. Thisincludes for each unit SATs-style tests at twodifferent levels, very simple low level tests for slowerlearners, extension questions to add to tests forfaster learners and Ideas & Evidence style questionsto add to tests.

2.6 Always moving and mixingSuggested finishers

◆ Finisher D Science Poem: This is a format for takingscientific ideas and making creative poetic outcomesfrom them. The poetic outcomes are constrained tomake them easy to do. Encourage pupils to use ICTand different fonts to present their work. Pupils mayneed a dictionary or a thesaurus as a prompt. Thismakes an excellent display item when processed andillustrated using ICT skills.There are a set of rules for constructing the simplepoem provided. Print this out, make it into an OHPtransparency and use it with a class. Some examplesand a list of suggested first words are also provided.This idea was supplied by Caroline McGrath (ASERegional Officer SE)

◆ Set up the blackcurrant squash/water demo. This cantake more than a lesson to develop mixing – so thismay need to be observed over a longer period of time,come back to this at the start of the next lesson.

◆ Completing the test.

Homework◆ Homework 2.6 Always moving and mixing can be used

to consolidate ideas.◆ Literacy activity Watching Changes on pages 26 and 27.

Pupils should read the text and answer the questions.

SuggestionsLiteracyAs well as the questions to answer, this spread is followedby a Literacy Activity entitled ‘Watching Changes’. Thisactivity has a focus on visualisation and NLP. Make a list ofthe target vocabulary (see Q3) and discuss with the classwhat these words may mean in other contexts. It isimportant to separate their specific scientific meaningsfrom other more common usage and for pupils tounderstand which is in operation.

ICTThere are several applications that demonstrate diffusion.The best of these is States of Matter by New Media.

Key skillsLiteracy in ‘Watching Changes’ activity and conceptmapping on the Finishing Off page.

Cover friendly rating3 stars (textbook), 1 star (activity), 4 stars (LiteracyActivity), 4 stars (Finishing Off!)


55


Experimental notes* To colour polystyrene balls (spheres) use water-basedpaint.

Answers1 a) Mug of sand makes a cone-shaped pile when

poured out.


Glass jar with lid (454 g jam 1jar or 500 cm3 jar)

Expanded polystyrene 35–40balls (19 mm)

Expanded polystyrene balls – 10–15coloured (19 mm)*

Pencil (standard size) 1

Large hexagonal stick 1

b) Mug of milk makes a flat puddle when pouredout.

2 The lights held by the carnival dancers would moveabout rapidly and go everywhere in the carnivalspace.

3 Diffusion spreads the smell.4 A perfume smell will diffuse across a small room in

about 30 seconds.5 The particles spread through the air like carnival

dancers.6 More particles are hitting the inside surface of the

can than the outside surface.7 Accept any sensible answers.



Activity sheet

Place some white polystyrene balls in aglass jar. Make a layer about three ballsdeep.

Draw carefully how they fit together in thesame layer and one layer on top of theother.

Explain the pattern they make with eachother.

Add another layer of different colouredballs.

Make the balls vibrate slightly by putting asix-sided pencil on its side under the jarand turning it, or by shaking the jargently. This is a good model for a solid.

Chapter 2

Make the particles start to mix together byshaking the jar gently. This is a goodmodel for a liquid.

2.6 Making the particles dance

glass jar

dark ball

white ball

balls vibrating

turn pencil and balls vibrate

balls jumpingabout more

mixing of coloured balls

bigger hexagonal stick

Heating up a solid makes the particlesmove faster.

Make bigger vibrations under the jar byusing a bigger pencil-like stick.

Watch what happens and explain how twoliquids can mix together by diffusion.

Place a lid on the jar and shake it rapidly.This is a good model for a gas.

Imagine what would happen if the lid wasonly lightly fixed on.

Explain how gas pressure affects thecontainer the gas is in.

Explain why gases diffuse rapidly across aroom.

lid

shake and ballsmove about

rapidly



2.6 Always moving and mixing

1 Look at the diagrams and then answer the questions below.

a) What happens to the ink after a few minutes?b) What happens to the ink after several days?c) Why is it important to draw the ink in carefully and not movethe syringe about?d) How does the idea that liquids are made of particles explainwhat happens?

2 If a diver gets a cut, a shark may be attracted to it from a longway off. The shark knows the diver is injured even though itcannot see the diver. How does it know this?

3 Use the word list below to complete the passage.

vibrate random compressed gas particles place volume solid solids can

A ______ is a fixed shape. This is because all the particles stay inthe same ______, but they can ______ slightly. The particles in aliquid are in a ______ pattern, but they are still touching eachother.

This is why ______ and liquids cannot be ______. The third stateof matter is a ______. In this state the ______ are all separatedfrom each other. A gas ______ be compressed. It can besquashed to a smaller ______.

4 Copy the passage out, using the words below to fill in thespaces.

melts vapour smell lower water boil 78 °C alcohol liquids freezes

Often we say that 100 °C is boiling point – this is wrong. Onlypure ______ boils at 100 °C; other liquids ______ at othertemperatures. Pure alcohol boils at ______, for example. At thistemperature ______ turns into a ______. You can ______ thevapour in the room. Water ______ to form ice at 0 °C and ice______ to form water at 0 °C. Alcohol freezes at a much ______temperature than water.

syringe

water ink

inkwaterwater in

syringe

then carefully draw up a layer of inkso that two separate layers are formed

draw some water into the syringe

(a) (b)

Documents

Pupil’s Book A Chapter 2 Changes - nothingnerdynothingnerdy.wikispaces.com/file/view/HW+Expansion.pdf/217931448/... · English. Be careful to make the distinction between material