Cambridge primary science 6 learners book

lntroduction I Humons ond onimols l.l Body orgons The heort 1.2 -l.3 Heortbeot ond pulse lungs ond breothing 1.4 -l.5 The digestive system l.6 The Whot the kidneys do? 1.7 Whot does the broin do? 6 B r0 12 14 16 Check your progress IB 20 Living things in the environment 2,1 Food choins in o locol hobitot 2.2 Food choins begin with plonts 2.3 Consumers in food choins 2.4 Food choins in different hobitots 22 22 24 26 28 2.5 Deforestotion 2.6 Air pollution 2.7 Acid roin 2.8 Recycling 2.9 Toke core of your environment 30 Check your progress 40 Moteriql chonges 42 42 44 46 3.-l Reversible ond irreversible chonges 3.2 Mixing ond seporoting solids 3.3 Soluble ond insoluble substonces 3.4 Seporoting insoluble substonces 3.5 Solutions 3,6 How we moke solids dissolve foster? 3.7 How does groin size offect dissolving? Check your progress eontcnts 32 34 36 3B 4B 50 52 54 56 Forces qnd motion 4,1 Moss ond weight 4.2 How forces oct 4,3 Bolonced ond unbolonced forces 4.4 The effects of forces 4,5 Forces ond energy 4.6 Friction 4.7 lnvestigoting friction 4.8 Air resistonce ond drog Check your progress Electricol conductors ond insulotors 5,.l Which moteriols conduct electricity? 5.2 Does woter conduct electricity? 5.3 Do different metols conduct electricity equolly well? 5,4 Choosing the right moteriols for electricol opplionces 5,5 Circuit symbols 5,6 Chonging the number of components 5,7 Adding different components 5,8 Length ond thickness of wire in o circuit 5.9 How scientists invented botteries Check your progress Reference Glossory ond index Acknowledgements 5B 5B 60 62 64 66 6B 70 72 74 76 76 78 BO 82 B4 B6 BB 90 92 94 96 r06 112 Contents p:''i ::r; ;-{f"' ffi ;l " | *& :: ::::'-:,-_ &",,& %l t'; :l: q *d, z*4zl:* :*:,: e'.**e;'d *\ &: *;, ''-.e: '4"# *:'; #" * *& '1d#4 z :* ?.: '?-: &: %) i>e -t'.'e ta# *.,,# 'r/'Iord.s to ledrn orgons orgon systems You hnow whot the outslde oJ Uour body looks [ihe But what's inside Uour body? ir7:?44.eEE-,€4+r;-.e=-=.-: =-= I F'Numrons snd qnlrncxls heort pump blood oround the body? ' '' "'." ?, -> Everg tlme the heort muscte r z blood carrying oxvsen ts protected bg the rlbs ,*,,f -"'#n{+:f-' ,rtfft"'u"o*3qi;;1g{'flira-' Blood is o red [iquid thot flows oround the bodg [n blood vesse!s Looh ot the lnside oJ gour wrist Sometimes Uou see the blood vessels through heart Uour shin Blood vessels run Jrom the heort to the lungs, around the body and boch to the heort The blood carrtes Jood and oxygen to o[[ ports oJ the bodg It atso pichs up woste products Jrom the bodg and corrles them to orgons which ger rid oJ them The kidnegs and lungs ore two oJ these orgons blood carrying oxygen from the lungs The heart, blood vessels ond blood Jorm the circulofory systern Que.stfows, a Whot does the heort do? b Whg does it this? at I What ls o heortbeot? Why does the heart pump blood to the lungs beJore i,t pumps blood to the rest oJ the body? Whs.* gawhgwe Z*wyw*^ ,5 The [eJt stde oJ the heort pumps blood thot contolns oxugen to the rest oJ the body g; The right side pumps blood without oxggen to the lungs ffi'eo'U&eiwge Whot is a heart attock ond how [s [t coused? '"##*l'*;:';a*tr%** , MflTclk obout itl How you fell thot your heort is beoting without putting o hond ***,,on your chest? g; The blood carries Jood ond oxygen ro a[[ ports oJ the body ond carrles owou woste products Jrom the dijjerenr ports oJ the bodg I Humtrns ond onirnols Suni[ trles the others For on occurote meosurement, use the smo[[est meosuring cglinder thot the Liqufd wt[[flt into Use this poge to hetp you choose whot you need Jor gour investigotion ffiE digitaltimer measuring beakers scales P D w dropper \ measuflng spoons filter paper m scales rulers tr H trFX @ HFf Et= cl c? measuring cylinders thermometer & bulb in holder $!! forcemeters multimeter ffi % motor 1.5 V cell l-\ J-) fun nel dropper @ tape measure Using o forcemeter Turn the nut to chech the Jorcemeter is set to zero Put the object on the Jorcemeter Put gour eye tevel with the pointer ond read the scole The weight oJ the bononos [s o Jorce oJ Jour newtons Mong Jorcemeters olso have a scale that wilt show the mass oJ on object in groms or hitogroms The bononos hove o moss oJ obout 4009 Some Jorcemeters also be used to meosure the size oJ o pushi.ng Jorce A Jorce oJ obout 2.5 N is needed to push this book ocross the toble Using scoles These sco.les ore not set lo zero Look Jor o wheel ot the bock oJ the scoles Turn the wheel to set the scoles to fl Lroo ,oo./ \e *,1/ zero Put qn object on the scoles The scales wi[[ show the mass oJ the object This oppte hos o mass oJ 250 g ncrarsnaa I There ore oJten potterns tn results The pattern mlght be results thot are otl the some, or i.t might be meosurements that go up or down Fem[ and Kwast ore investlgoting whlch moteriols conduct e[ectricitg ,,,, Theg ore testlng objects mode Jrom d{ferent moteriols The butb tights when the materlol conducts electricitg Here ore their resutts j plostic iJ" oloss -"" I: metol i l:tgr* l?eferenee " off t'.::',:,,t,,X1:: : a pattern i,n the results Some oJ the results ore the same He uses the pattern to mahe o conclusion ]s Feml correct? Femi hos seen Kwast hos seen o result thot does not Irt the Pattern Metal conducts electricity Materials that are not metal not To chech thot theg hove not mode o mistake, theg repeot the test with the graphlte The butb tights up everg time So Feml's conc[us[on [s not right They mohe new concluslons Some materials that are not metal conduct electricity :: Yoho and Morjo ore lnvestigatlng how running olfects pulse rote TheU wont to hnow f their pu[se rote [s d{ferent when theg run at dfferent speeds Yoho runs the same dlstonce each tlme but ot three dfJerent speeds To mahe thelr results retlab[e, Yoho runs ot each speed three ttmes Theg meosure her pulse rate oJter eoch time They ore going ro tohe the avero,ge pu[se rote Jor each runnlng speed by ftnding the meon ls your pulse rate different if you run at different speeds? f?efer*nce ;.::: Here ore the[r results so Jor PulseRotelinbeots lrOz itqO P_._tJt-Yl? _i _qs Pulse Rote in beots i f g-.-,-T-lyl.- -i-ots'188 rts l88 !"i tl - _ i _ iirza 178 izo *.i,- - - i ltZ li * _p ._tn!_yl9' _"*-_"_i _ _i _*i*_.** "l ii; fillesm pulse rqte beqts per rminute irSS 1, :i, in I *, " -, : 153 i_- .,_-_."i_.- *,*- *.'-.- .- -_ .-.*_.,-.**.-* _-."{ The gi.r[s looh Jor potterns in their resutts The numbers Jor runnlng very Jast ore olmost the same But there ore two meosurements ln the results that could be wrong Looh Jor numbers thot not ftt the pottern The girls repeat two meosurements to chech thot they ore reliab[e Then they calculate the meon Thetr results now look tihe thts *l ;';;;ff;; purr i n.i r i;;;;"-l-fi0 - $p.tminute i P.t minute ertr Rote In $ Pulse i beotsi beots Meon putse rqte : i 188 188 in i-il|** Marjo mohes o concluslon The foster you run, the foster your heort beots Reference r02 i;; , rss I , ! t1 178 ltA 210 148 148 'i 21O ; 17s i- G; When you repeot i* I ! The girls exploi.n why they repeated their meosurements meosurements it is eosier to see if you hove got one of them wrong : Also, you find the meon so your results ore more relioble Sometimes a sctence lnvestlgotlon [s not the best woU to onswer o question You mou not hove the equlpment Uou need or enough time The answers to mony guestlons be Jound in reJerence books or on the lnternet Mai Choosing i.s reseorchlng Jood choins ke_v wonCs First you should thinh obout which words to [ook Jor These should be heg words Jor the topic gou ore reseorchlng Moi could look Jor diet, consumer and prey l Jsing referencg frr.:g,e x Scan the contents poge Jor these words and look them up in the index Trg loohi.ng up consumer ond prey in the i.ndex to thi.s booh Con you ftnd out obout the dlet oJ an onimol? 1",!sing the inierr:et Thtnh coreJultg about the words Uou type into o search engine Seorches Jor 'Crocodi.le diet' ond 'Whot crocs eat?' w[[[ list d{ferent websltes Not atl the inJormotlon the lnternet is correct, so [ooh careJullg ot the websltes that come up on gour seorch Some ore more tihety to be correct thon others Moi hos Jound two websites with inJormoti.on about whot crocodiles eot Which you thlnh i,s more reliob[e? ftnd retioble websltes, looh Jor those thot come Jrom lorge orgonisotions ond ore wrltten bg experts Unre[iob[e websltes oJten have adverts ond not [ooh To as good $?efer*n*e &Lt g@.\ ,:n ::wi? {i ,4'i ,r f F tr';r,tr': ; '*#' ,# *# "*,*.* ,3 € ,=#e * ;I "#4i *.i ;i f - :-7-tr" ka "" f f* ffi *#; "# € ";, : a P * Poge t roln that contains dlssolved nltric oxides or sufur di.oxi.de; these compounds mohe the roln acldlc 34 the Jorce coused bg oir pushing ogqinst movlng objects 72 fi"mptrre the unit used to measure electr[c current 80 enstltrnm on allerg[c reactlon thot couses o person to have d{frcutty breathing 32 rrlrn ncnh orc uLrrrvJfr'rL!rq the mixtuye oJ goses surrounding the Eorth 32 eLtdi.t o sortlng qnd checking exercise 3q uLltt t tlti t mln reslst&mee bmLmneed ff*rees) when two Jorces octing on on object ore eguol and opposlte Lr^*|nr,, 62 uuLLtr r :j o source oJ electrical energU thot consists more thon one cetl bl"**d vesse[s specio[ tubes thot carry the blood hr*"Ln the orgon thot controls bremthrinmJ the wog we tohe oir into our bodies ond let lt out oJ our bodies 12 o lung inJecti.on thot be caused by pol[uted olr 32 bronchitls t crrcuir 0rftErfim al.l oJ 76 q body Junctions 18 o plcture oJ o circuit that uses sUmbots to represent 84 components ^+;^^ T LTI LLI,T(JLLLII *1 ,"^,,1 the pumping oJ blood a[[ oround the body rirrtt !nf nrr r r \-Ll \-r*LLr,LL./ \tl\tvrrr the system Jormed by the heort, blood vessels ond blood to corry Jood ond oxggen oround the bodg q e.,**a* -f"'""' e CImp0st rotted vegetab[es ond gorden woste thot used os o Jertlllser **ossony snd irldex ls 37 conctude to declde somethlng i.s true aJter looking ot ott the evldence gou hove collected 53 conductor (oJ etectrlcity) o moterlal thot altows electrici.tg to poss through it 76 connector o devlce to connect two wlres together 80 conserve to keep to protect Jrorn extlnctlon o living thing (usuo[[g on animoD thot eots onother ptont or onimal 31 deJorestotion removot oJ trees by humons 30 depict when you depict an i.deo you show i,t usi.ng a dlogrom or drowing 22 desert reglons with verg little roinJall 28 diotys[s o wou to remove wostes Jrom the blood wi.th o mochlne f the hidneys not work properly consumer digestion dlgestive sgstem disease dissolve distitled (woter) drog soJe, 24 lr:i:!r:::-.rr: : 17 1u!,riiltri.i:ija:r:-::::: : the process oJ breoking down Jood into verg tlng porti.cles 14 the orgons needed Jor the process oJ di.gestion including the stomoch ond lntestlnes 14 on itlness which stops Uour bodg Jrom worki.ng properlg 17 when o substance, oJten o so[i.d, mlxes with o tiguid and becomes port oJ the tiquid 46 woter thot has been boiled and the steom hos condensed to gi.ve pure woter 78 eftergy onother nome Jor oir reslstonce 72 when somethlng hos energU, [t mohe things move ond cous6 things to-ihonge; a[[ tiving rh"lngs need energy to exlst 24,66 environment our noturol surroundings 30 ^., ^+;^^ gALI gLN,UI t the process oJ removlng oJ waste products Jrom the body 16 to push or pu[[ to create a Jorce on item to conslder when deoling wlth o problem 60 or investigati.on 25 o sieve which lets through tiguids ond dissolved substonces but not insotuble substonces 48 a method to separate mixtures mode oJ a solid ond llquid using o frtter 48 fmmei ehsin o wou to describe the Jeeding relotlonship between plonts ond onlmols 22 $^r., o push or a pu[[ thot trles to change the posltlon or shope oJ an object 58 ovafl {m r+ nr J urL Lr , r rt Jurer f, l+^*i* ^ rLLrr u ty J JVrvv r t J0rce 0rogr0m drawi.ng that shows the di.rectlon ond size oJ Jorces acting on on object frirrinn- a Jorce which trles J' " ' to stop thi.ngs slidlng post one onother 68 the graduol lncreose [n temperatures throughout the world 30 the Jorce thot putls objects towards the Eorth s8 31 keant a gos that trops heot couslng the temperoture oJ the otmosphere to rlse, Jor example, corbon dioxide o special muscle thot pumps blood around the body i"nsolubLe cannot dissotve 46 insuLatmr (nf electnleltE) o moteriol thot does not all'ow electrlcitg to poss through it 76 Lntestlnes the orgon whlch breahs down Jood tnto tlng portlcles that move lnto the btood; undigested Jood [s pushed out ot the end oJ the intestines 14 connot be changed boch to what it wos beJore 43 ttt gtooflr wormrng rt v' rlt ti+ t t Yr uv rLy I greennouse Eos i"nnevenslbl.e Glossory qlnd indeN beon-shoped organs thot frtter blood to remove ki.dneg woste kllogrml'n Lcne[$LL (stte] products meosure oJ moss eguo[ 16 to 000 g 58 where woste products Jrom o town or city are disposed oJ or buri.ed 36 lubrie mte to put a substonce, such os o[[, on o surJoce [n order to reduce Jri.ction 6q I'rnnc Lur Ly J the orgons we m&55 mlxtr*re multi"rneter negetlve n pr\/pc mervOus sUstelrr net ffcree) Jor breathing the omount oJ motter [n an object, meosured in kitogroms 58 Jorms bg when two or more dfJerent substonces mixed together but ore not chemicatly 44 a plece oJ eguipment Jor meosurlng current, voltage ond reslstance 80 use joined eJJect frbres which carru messages to and Jrom the brain the broln ond nerves somethlng thot does not hove o good the overollJorce when two or more opposi.te Jorces ore not in bolance welght newtor"l the unlt used to meosure 0rgen o port lnside the body thot corrles out a specftc Junctlon to heep us o[[ve dfJerent orgons that worh together to corru out o certoln Junctlon in the body CIr$m.n systern 12 30 '18 18 63 58 on unwonted plont or onimal, such os on lnsect thot eots Uour flowers 22 plmnkton tiny plonts ond anlmots that live in the seo 2q yLuy a devlce Jor connectlng an electrlc wlre or coble to on electricity supptg 82 substances which cause pollution 32 pest pCILLutmnts Glosssry snd index poLLutlmn moking the envlronment dlrty with woste products 32 nncif irrou something that has a good eJJect 36 predetO!" o consumer thot eots other onimals (which are thelr prey) rvJrLlv tlrDcc I r rc rr uJJul u the Jorce that pr'8u on animol that is eoten bg onother onimol (o predator) i,s put on somethlng 26 10, q0 26 o plont that produces energg Jrom sunlight o smatl beot Je[t under the shin due to the pressure oJ blood os the heart pumps it oround the bodg 2q pl.{f"s (wextcr} woter thot contoins no impuritles such as salts 78 l'mtg how Jast somethlng happens 52 r€eet when substonces ore mi.xed together and chonge chemicolly to Jorm o new substonce 44 pr0d.ue er nr rlco l-,4LJu rea$e tr&s -^ ruuLY to re-process something and mohe lnto o new product 36 ,.*"4,, to decreose neslstfi"rue e the omount oJ oppositlon to the Jto* oJ current o store oJ something necessaru Jor ['rJe, such os woter, energu and minerols r ro(n! !rrr) 10 36 q0 38 rsvenslb[e be chonged boch to whot [t was beJore s*l.i"ve tiguid produced $&vennehl grossland reglons with o tropicol climote 28 58m&r&te I to 44 s€rl€s eireu{"t o circult where the electri.city onlg has one on[y poth to flow olong 84 a moterial or plece oJ eguipment with ho[es [n [t thot wi[[ onlg o[[ow substonces oJ o certaln size to go through the holes 45 dlssolve 46 sLevc snLi"rbLe &lo*sory ond index di.vi.de i.n the mouth or sptit something i.nto d'rlJerent ports 42 15 solute the moterlal thot di.ssolved 50 smluti.on o mlxture oJ one substonce in onother, where the dissolved substance no longer be seen 50 snLverrt the tiquid in which a solute dissolves 50 snrt to put things in groups occordlng thelr tUpe 45 spee ies o portlculor type oJ plant or onimol 23 stomme h the organ which mixes chewed Jood with di.gestive jui.ces to Jorm o thich l"iquid 14 surfmee &re& the slze oJ the outside port oJ on object 71 suspensloru a cloudy mlxture oJ insoluble solid porticles a liquld al i,s i.n 47 tropical countrles lie between the tropi.cs where the cllmate is hot and wet; 23 degrees north or south oJ the equotor 28 turnouR o growth on bodg orgons 1q unbs.[m.need {n rro< J when two or more Jorces octi.ng in opposite dlrectlons on an object ore not the sqme slze 63 un$orm the same throughout 51 uni"que not lihe angthi.ng else 29 ur{.ne the liquid woste excreted by the kidnegs 16 't wErgni the omount oJ Jorce thot pults objects towards the Eorth 58 A wetlond is o place thot woter most oJ the tlme 48 tr"opie wetl"eind windpipc w*rk i.s covered in shollow the tube thot carrles alr Jrom the nose ond mouth to the lungs ond boch agai.n 12 the omount oJ energu tronsJerred when a Jorce makes an object move 66 Slossory ond index ? F {'\, i "': r ;,9., "*-8 F, =f ond publisher ore groteful for the permissions gronted to reproduce copyright moteriols While every effort hos been mode, it hos not olwoys been possible io identify the sources of oll the moieriols used,or to troce oll the copyright holders lf ony omissions ore brought to our notice, we will be hoppy to include the oppropriote ocknowledgements on reprinting The publisher is grotefulto the experienced teochers Monsooro Shooib Shoh, Lohore Grommor School,55 Moin, Gulberg, Lohore ond Lynne Ronsford for their coreful reviewing of the content, The outhors p Alexonder Semenov/ Science Photo Librory; p 10 Lucion Comon/ Shutterstock; p 14 bikeriderlondon/ Shufterstock, p 16 Stuort Monk/ Shutierstock; p Picsfive/ Shutterstock; p l9 Gemenocom/ Shutterstock; p 22 Molcolm Schuyl/ Alomy; p 24 Rolph Loesche/ Shutterstock: p.26fr Trovel USA/ Alomy: p.26blCothy Keifer/ Shuttersiock: p,26br Mike Roobe/Design Pics lnc,/ Alamy: p.27 nico99 / Shutterstock: p.29 digitolunderwoter.com/ Alomy; p 30 Sue Cunninghom/Worldwide Picture Librory/Alomy;p.32f ssuophotos/ Shutterstock:p.32b John McKenno/Alomy:p.34Vonesso Miles/ Alomy; p 35f Rolf Bender/ Fronk Lone Picture Agency; p 35c Corolino Biologicol Supply Compony/ Phoiotoke/ Alomy; p.35b lmogebroker/ Fronk Lone Picture Agency; p,36Tony Whorton/ Fronk Lone Picture Agency; p 38 Kuzmo/ Shutterstock; p,38 Rebecco Hosking/ Fronk Lone Picture Agency; p,42 Bochkorev Photogrophy/ Shutterstock; p.43fr pogonici/ Shutierstock; p.43flAbelTumik/ Shutterstock; p.43b i love imoges/ Alomy; p 45 Twin Design/ Shutterstock; p.46 Elisobeth Coelfen/ Alomy; p 47 GlPhotoStock/ Science Photo Librory; p,48 cvolle/ Shutterstock; p,49 Gollo lmoges/ Alomy; p.50 lokov Filimonov/ Shutlerstock; p.51 f Helene Rogers - Commerciol/Art Directors &TRIP/ Alomy; p,51b Robyn Mockenzie/ Shutterstock; p,55 Joson Potrick Ross/ Shutterstock; p.56 Robyn Mockenzie/ Shutterstock; p 58 ond p, 59t Mortin E Chillmoid/ Science Photo Librory; p 59b Dennis Hollinon/ Alomy; p 60 Todd Wornock/DigitolVision/ Getty lmoges; p.61 Rolf Richordson/oge fotostock/ Alomy; p.63 Fuse/ Getty lmoges; p.65 Horizon lnternotionol lmoges Limited/ Alomy; p.66 Chris Cooper-Smiih/ Alomy; p.68/ Rofo lrusto/ Shutterstock; p, 68r Elnur/ Shutterstock; p 69Thomos Muller/imogebroker/ Alomy; p 71 Petor lvonov lshmiriev/ Shutterstock; p.72 Richord Thornton/ Shutterstock; p, 73 Tom Tschido/ NASA; p 74 Jock Sullivon/ Alomy; p.7Bb stockyimoges/ Shutterstock; p 7Bc majeczko/ Shutterstock; p TBfTobby Mittins/ Shutterstock; p, B0 Brogin Alexey/ Shutterstock;p 83 worldpix/ Alomy;p 86 @ Cynthio Clossen/Flickr Open/ Geti-y lmoges; p BB/ sciencephotos/ Alomy; p BBc/ ekipoj/ iStockphoto; p BBcr Krys Boiley/ Alomy; p BBr Dovid J Green - engineering themes/ Alomy; p.9l Christopher Brignell/ Thinkstock; p 92t Bowl, lron, Sosonion period, 4th-sth century (silver ond gilt), Persion School/ Freer Gollery of Art, Smiihsonion lnstitution, USA/ The Bridgemon Art Librory; p.92b Mory Evons Picture Librory/ Alomy; p 93 Sheilo lerry / Science Photo Librory Cover ortwork: Bill Bolton /= lefi, r= right, l= toP, b = bottom, c = centre ,&c k a"l ew ed * ge nn* e n?x Combridge Primory Science is o ftexibte, engoging course written specificolty for the Combridge Primory Science curricutum fromework (Stoges 1-6) The course offers pl.enty of teoching ideos to give ftexibitity, otlowing teochers to setect octivities most oppropriote to their ctossroom ond pupi[s An enquirybosed sty[e of teoching ond leorning is stimutoted, with the Scientific Enquiry objectives integroted throughout to encouroge leorning of these skitts otongside the scientific concepts The tonguoge [eve[ is corefutty pitched to be occessibte to EAL/ESL leorners, with concepts iltustroted through diogroms to otlow visuoI understonding ond leorning This Leorner's Book for Stoge covers ot[ the objectives required by the curricutum fromework in on engoging ond visuotty stimuloting monner .The Leorner's Book contoins: Other components of Combridge Primory Science 6: r usefuI itlustrotions thot exptoin concepts to hetp visuo[ leorners ond those with lower Activity Book Iiterocy For our fut[ ronge of Combridge Primory tittes, inctuding Mothemotics, Engtish ond Gtobot English, visit educotion.com bridge.org/co mbridgeprimo ry c o octivities to devetop Scientific Enquiry skitts ond support [eorning through discovery key vocobutory pointed out os 'Words to Teocher's Resou rce ISBN: 978-1 -107 -64375-8 IS BN : 97 8-1-'107 -66202-5 leorn' throughout r r o 'To[k obout it!' feotures thot give suggestions for ctossroom discussion key leorning points given os 'Whot you hove leornt' summories of the end of eoch unit, 'Check your progress' questions thot offer opportunity for ossessment Completely Cambridge Cambridge resources ror Cambridge qualifications Combridge University Press works with Combridge InternotionoI Exominotions ond experienced outhors, to produce high-quoLity endorsed textbooks ond softwore thot support Combridge Teochers ond encouroge Combridge Leorners rsBN 978-'l -1 07 -69980-9 ltillllilflililt ]ilIil]il tt7811O7tt699g}9tt> ... your progress Reference Glossory ond index Acknowledgements 5B 5B 60 62 64 66 6B 70 72 74 76 76 78 BO 82 B4 B6 BB 90 92 94 96 r 06 112 Contents p:''i ::r; ;-{f"' ffi ;l " | *& :: ::::'-:,-_ &",,&... hobitots 22 22 24 26 28 2.5 Deforestotion 2 .6 Air pollution 2.7 Acid roin 2.8 Recycling 2.9 Toke core of your environment 30 Check your progress 40 Moteriql chonges 42 42 44 46 3.-l Reversible... insoluble substonces 3.5 Solutions 3 ,6 How we moke solids dissolve foster? 3.7 How does groin size offect dissolving? Check your progress eontcnts 32 34 36 3B 4B 50 52 54 56 Forces qnd motion 4,1 Moss