ns cr

Chu ngcPcrspecti vc by DavidHrothcn A thesissubmitted tothe SchoolofG raduateStudies inparlialru llil lmcn[OrlhcrcquirclllcnlSrOr lhc ucgrccor

i\IasterofEd ncat ion Educa tion MemorialUniversityof cwloundl and

i\Iarch2111 2

St.Jnhns Newfo undland

ABST RAC T

When teaching st udentsabout DCcircuits.xivcrcomingpriorconception sabout electricitycanbevery cha llenging .Inthis study .a class ofgra de12 students wa stau ght auniton DC circu itsusin gAVOW diagr.uns.A VO W diagr am sarcanana logythai maps thcc ur rc nt.rcsisla ncc .vo ltagc.a nd po wc ro nlo a rccta ngu larsha pc insuc hawaythatthe dimCllsion s orlhcshapcarcrclat cdinthcsamcwayasthcci rcuitparamctcrs .

Classroo mobsc rvatio no r thcstuccnlsand tca chc r wc rc m adc w hcnA VO \\, diagr.unswcrcintegratedwiththeregu larteachingsequenceor the unit. At the endoft he unit.adiagn ostictestolstudc ntconcc pt io nsor DC circuitswasadministeredand a sam pleofst udents were interviewedabo uthow theyuscd A VOWdiagramsto learnand reasonabo ut DCcircuits.This studyconcludesbyevalua tinghow effec tiveand appro priatethe AVO W diag ramswere intheteachi ng oft hisunit.

For my will:JcnnymydaughterIris.and myson Isaac.Ourfamilywouldnever have existed butfixthestartof thisthesisandifit werenotlormylumily.thisthcsis would havenever ended.

Ican·tcvcnbcginloapologizctomythcsisad"i sor.Dr.KarcnGoodcnn ughfor whatIhaveputherthroughhut lcanoll l'!"mysincere and unendingthanks.

AsforMik e,thanksfore veryth ingandgoodluck withtill:newncw by.

iii

Tableof Conte nts Abstrac t Acknowle dgme nts

l.istofTablcs l.istofFig urcs List orAppe ndic es Cha pter IInt rod uction

1.1 Context

1.2 Method ol ogy 1.3 Structureofthe Thesis Chaptcr?LiteratureRe view

iii viii

xii

2.1 Definiti onofMisconce ptio n 13

")") Alte rna tive Conceptio nsorElectric ity 16 2.2 .1 CategoriesorCon cept ions orElectricity 17

2.3 Challengesinl.caruingAboutElectricity 2.'

2.3.1 StudentReason ing 2.,

2.3.2 Stude ntInte rpre ta tionandUnde rstand ing 27

2.3 .3 St udentl.xpc rt isc .'.'

2.3A TeachcrlnlluelKe sonStudentC on ccpt ionsor 35 Elcctr ic ity

2A Resea rchonConce ptualChange 36

2A.1 Conce ptualChangelramcwork 37

2A.2 l.xpan dcd ViewsofConceptualCha nge 3X

2.5 Analogies 42

2.5.1 Charac teristics ofAnalogies 43

2.5.2 Factors10ConsiderWhenUsinuAnalouicsin Science 4X

Teaching - -

2.5.3 TechniquesforUsingAnalogies 51

2.5.4 Potentia! ProblemsArisingFrom theUseorAnalogies 54 2.6 ~~~~~c~~~~gramsas anAnalogicnlMcthod or Teaching 56

2.6.1 NatureorAVOWDiagrams 2.6.2 RationaleforUsingAVOWDiagrams 2.7 ResearchonAVOWDiagrams

2.X Summary

ChaptcrLxt cthodology

5X 5'>

61

3.1 CaseStudyMethodology 66

3.2 DataCollectionMethods (, I)

3.3 Roleor theResearcher 73

3.4 UseorDIRECT1.0 7--1

3.5 Class roomObservutionsundStude ntIntervi ews 74

3.6 IntcrvicwCondilions andSlructure 75

3.7 GeneralCommentsAbout Interviews 77

3.X Sample 77

3.X.1 Schoo lProfile 77

3.X.2 Class roomContext 7X

3.9 Unitlrnplcmcnuuion 3.9.1 Modijie al ions c fl\ VOW Approac h 3.9.2 StudentHackground 3. 10 DataAnalysi s 3.11 Eth ica l Issues 3.12 Limitat ionsofi'ic Study 3.13 Summary Chaptera AnalysisofData

4.1 Implem en tat ionof the Teach ingUnit 4.1. 1 Lesson One:March22.2007 4.1.2 Lesson Two:I\pril2.2007 4. 1.3 Lesson Three :AprilJ.2007 4.IA LessonFour:I\pril4. 2007 4.1.5 SubsequentLessons 4.1.6 SamplesofStudent Work 4.1.7 OverallImpressions 4.2 DIRECT1.0 Results 4.2.1 Question2 4.2.2 QucstionS 4.2.3 Question6 4.2A Question 14 4.2.5 Question 15 4.2.6 Qucstion l?

vi

XI XI X4 X5 X7

91 91

93

100 103 111 111 112 114 115 117 120 125 127 129 132

4.2.l\ Qucstion Zr. 13(,

4.2.9 QucstionZ') 13l\

4.3 TeacherObservation s 142

4.3.1 Impressions of AYOW Diagrams 142

4.3.2 SuuucstcdModifi cat ions andFuturcUscofAYO W 143 Di; grams

4.4 Summary 144

ChaptcrSConclusions 5.1

5.1.1 5.1.2 5.2

5.3 5.4 5.5 5.6

vii

1101"Can theAYO W Diauram Analou vHeUsedto

TcachAbout DCCircuitsintheCont:~tola Typical Classroom'?

TeacherPreparationandPresentation UscofAYOWDiagramsas anAnalogy

~~~~~2:)(~~~,~)~~;:t:P~l~~1 ~~:~~~~.i)iagramS

RcconuncndationsfortheFurtherUscofAYOW Diagrams

SuggestionsforFutureStudy Summary

146 146

147 151 153

155

15l\

159 159

Listof Tables

Table3.1 Epistemologicalandontological perspecti ves Table3.2 ChengandShipstonc(200~b)unitteachingplan Table 4.1 CollectedresultsfixDIRI:CT 1.0test

viii

10:2

Figure2.1 Unipolar model. 17

Figure 2.2 Clashing currentmodel IX

Figure2.3 Atten uation model I')

Figure2A Scientific model 20

Figure2.5 Tworesistorsanda bulbinseries 2-1

Figure2.6 i\ combinationcircuit 25

Figure2.7 i\ representationofparallelresistorsusingaflowingwater analogy 2X Figure 2.X Movingcrowdsrepresentationof resistorsinparallel 2')

Figure2.9 Trainanalogy 30

Figure2.10 ewto nslawof universalgravitation -17

Figure2.1I Coulo mbslaw -17

Figure2.12 i\YOW diagram representalionof circuitp arameters 57 Figure2.13 Mappingrelationshipbetween ani\ YO W diagramandaDC circuit 5X

Figure3.1 DIRECT1.0 question 17 71

Figure-l.1 i\YO W d iag ramsforresistorsinseriesand paral lel ')-1 Figure-l.2 Acircuitdiagramof acomb inat ioncircuit 95

Figure -l.3 i\YOWdiagramforcombinationcircuit 95

Figure -lA i\YOWdiag ramsforacircuitbeforeandafter the resistancechanges ')(, Figure4.5 i\YO Wdi agramsfixthreed iffcrent light bulbs

Figure4.6 Circuit diagramfortwolightbulbsinseries Figure4.7 Tableforrecordin gcircuit parameters Figure-l.X Tableforrecordin gcircuitparameters

10-1 105 105 106

Figure--1.9 Table forrecordingcircuitparameters l-igurc-l.LOTableforreeordingeireuitparamcl ers l-igurc-l .fl Tableforrecordingcircuit parameters Figure--l.12 Completed lableo f eireuitparameters Figure--l.13 AVOW diagramforthecomplete circuit Figure--l.I--I AVOW diagram foraci rn.itsholl'inglll'oresis\ors ligurc-l.lS Circuit diagramto raparallel circuit Figure--l. 16 AVOW diagramforaparallelcircuit Figurc-l. L? Quizused asassessmentonApril 10.2007 Figure --l.IS Sam plcofoncstudcutswork Figure--l.19 DIRECTl.UqucstionZ

Figure--l.20 CorrectAVOW diagram for resistorsinseries Figure--1.21 Christine'sAVOWdiagramfortworesistorsinseries Figure--1.22 DIRECT1.0 question 5

Figure--1.23 Correct AVOW diagramsforDIRECT1.0quest ion5 Figure --1.2--1 l.isasAVOWdiagramfor DIRECT1.0 question 5 Figure --1.25 DIRECT1.0 question6

Figure--1.26 AVOW diagram forDIRECT1.0 question6 Figure--1.27 DIRECT1.0question1--1

Figure--I.2S CorrectAVOW diagramlorDIRECT1.0question1--1 Figure--l.29 DIRI:Cr1.0 question15

Figure--1.30 CorrectAVOW diagramforDIRECT1.0question15 Figure--1.31 DIRECT1.0question17

106 10(, 107 107 IDS IDS 109 liD

113 11--1 117

us

liS 121 121 122 125

12S 12S 130 130 132

Figure 4.33 DIRI:Cr1.0 question 21 134 Figure 4.34 Correct AVOW diagramforDIRI:Cr1.0question21 135

Figure4.35 DIRECT1.0question 26 136

Figure4.36 Correct AVOWdiagramforDIRECT1.0question26 137

Figure4.37 DIRECT1.0question29 13')

Figure 4.3XCorrectAVOWdiagramItH'DIRITT1.0 question29 140

Figure AI AVOW diagram ofacircuit withoneresistor 173

Figure A2 Aschematicdiagramola DCcircuit withone resistor 17., Figure1\3 Mappingrelationsbetween AVOW diagramsand DCcircuits 174 FigureA! ADCseries circuitandtheAVOWdiagramforthecircuit 174

FigurcA5 Aparallel DC eircuitanJ ihAVOWJiagram 175

FigurcAo IncorrectAVOWdiagrams 175

FigureA? Mappingrelationshipstorcircuitswith multiple resistors 176

FigureAX Allenu ationmodcloflightbulbsinseries 177

ligurcA'J AVOW diagramsto cxplai n current consllmptionmodcl 177 FigurcAIOAparallelcircliita ndtheA\lOW diagram ltlr t\\'oeqllivalent resislors 179 FigurcAl l Correctand incorrectAVO\\,diagramsforparalleland unequal 179

resistors

FigllreAI2 Acircliit to ililistratescqllentiai rcasoning IXO FigllreAI3 AVOW diagramstoililistralescqucnlial reasoning IXI

xi

l.istofAppcnd iccs Append ixA AVOWdiagrams AppendixB DIREC'!'1.0Test Appendix

c:

xii

172 IX2 1')3 195

Teachingelec tricity tohigh school physics studentscan hc achall cnuin g experience, Stude ntsdonot easilyle tgo of theirpre viouslygeneratedconceptions abo ut elec tric ity(Dilhcr&Duzgun.200X:Mcl.rcrmot:&Shaffe r.1( 92 )andwhenthey do adoptsc ie ntificconce ptionsofelec tricity.the y often re ve rt backtotheirearlier concep tions(Lic ht.1( 9 1).Toaddtothisdifficulty.studentswill also inco rrectly reca ll phe nome non that theyhav eobser vedinorder to suppo rttheirincorre ctideas (D uit&

Rhoncck,199X).

Stude ntconceptio nsofelectricity arewelldocum ent edinresearch liter atur e.

Studentconce ptio nsprogressfromvery naive conceptio ns10vcrvsophistica tedand scientificonesas studentsageand develop(Os borne.19X3 :Shipstonc ,19X-l ).Each add itiona lstageof de vel opme nt ismarkedby ane wawa renessofsomeaspectof electricity: aneffort torationa lizethisnewl yobservedaspectofelec tricity . and an auc m pt rointegratethisnell'awarene sswith thestude nt'sprevailingconceptionof elec tricity.Forexam ple.thesim plestcon ce ptionofelec tricity istheunipol armodel whereelectrici tyflowsthroughone wirerrorna sourcesuchas abatte ryto adevi ce such as alight bulb.Thismodel is suffic ientunti lit isnoticed thatthere mustbe twowires for electric ity toflow.Thc clashi ngcurrcms modelaccountstor the need fortwowire sby supposing that the rearetwotypes ofcurre nt thatflowfromthe source and whenthey Illedatthedevice.theyrelea se energy.lJpo n lea rn iugthat the re isonlyone type of currentand thatit flow sinonlyonedirecti on.anuttc nuation modclisadopted10explain why batte riesrunoutofenergy.Eac h devicein the circuit cou sumc sclcctri citylea vin g

lcsxclcct ric ity for thenext device and thebaucrylose selectricityuntil itisdead.linall v.

when it islearn ed thaiCUITentisnot consu med.till: scientificconceptionof circuits(;111

he developed .

Whi lenotallst ude ntswill developwhatisconsideredto hesc ie ntificconceptions of electric ity. high sc hoo l physicsstude nts arc expect edtohavesophisticatedconce ptio ns ofe lectricityand theyarccha lle ng ed tousctheirconce ptio ns topredictandexplain aspectsof electricalphe nomenonthatnon-physic s stude ntsmayneverencount er.Asa high school physicsteach er.on e cha lle ngethatIhav c Iaccdishelp ingmystudents developmoreso phisticated conceptionscfclcctricity,Thisresearchstudydescribesmy investi gation ofatoolintendedtohel p physic s st udents developthe conceptionsthatthey needtoholdinorde r tohe success fulin theirstud ies.

Electric ity iscom monly explainedthrou ghtheuscof anal ogs.Forexample,the presence of equalnumbersofoppos ite chargesresultingin neutrali tyis com pa red10the behaviourofinteger s,Atomscon tain equal mil11her s of positiveprot onsasnegative elec t ro nsandforelect ricallycha rged objectssuchas ions or a halloon that hasken rubbed withahitof fur.thetotal chargeisequaltothesumof thenumberofelec t ro ns alitIthenumberof prot ons.Theatt ractionofoppos itecha rgesis com pa red to oppo site ma gneticpole swhere a po sitive elec tricchargeattracts anegativ e oneand repel sanother positiveone in thesamewaythat a northma gnet ic po le will attractasouthmagneticpole and repelano the r northpol e.Theno ll' ofelect ric cur re nt iscomparedto thenoll' of wat erwherethe watermolecule s arc like the elec t rons.the amountof waternowingis likethe curre ntand the pressureofthe noll' islike thevolta geor potentialdifferen ceof

in thestudyofe lec tricity.Differ entanalogies elicit diffe ren t predictionsabout whatwill happenin a circuitand it isnecessar yto swi tc h betweenana log ies to predictand expla in vario us electricalphenomena.Thiscan lead toconfusionandfru stra tio nforstude nts as theyworkto develop theso phisticatio nreq uiredtomol'(fromoneanalogy toanother.

Thisresearchstudy investiga tesAVO Wdiagrams.ananalogythatcueapsulat e s allolt hc behaviorofDC circ uitsinalogically consis te ntandeasytound er st andway.

AvOw diagramxwc rcdcv clopc d hyChe ngandS hipstone(2 003a).Ratherth an representingelec tricityasflo wing wate rorcrowdsmo vingthroughcorridors.diagra ms tha tport raythe basic clemen tsofu circuit:cur re nt(nmpcrcs ).voltage (volts ).resi stance

(ohms). andpowcrtwaus )arc usedtopromot e conceptua lchangein high schoolphysi cs stude nts.Currentisthef1011"of electro nsthro ugh thecirc uitand is conservedthrou gh out the circ uit. That is.thesame numberof electronsthatenteranypartof the circ uit isequal tothenumberofelectronsthatlea ve thatpart of the circui t.Itistheelectron sthat carr y theene rgyusedbythe circuitclements.Theamo unt of energythateachelectron carries isdescribedbythe te rmsvoltage or pote ntia ldifference.Thesetermsarc used intcrch.mgcablyand they arc measured byco mparingthedifferenceinenergythat an electron hashe fore enteri ngandalte rleavinganysectio nofacircuit.Anelectron's energywilldecreaseverylittlewhenit travelsthrou gh a sectio nofw ireand it will decr easemuch mor ewhentravell ingthroughade vice suc halightbulbora resisto r. The

sum of allof these voltagedropsorpot c mialdiffe re ncesisexac tlyeq ua l to the voltage

suppliedbythe bat te ry. Each volt age dropoccurs becau se each par t ofthecirc uitresist s

theflow ofelectri c ityandthisresistan ce conve rtsthe encrgy carriedbythe electroninto ausefulformsuchaslightfrom alightb.ilbormotionfrom an electricmotor.Finall y . powcrmea suresthe rateatwhichthe energyisused.

A VOW diagramsarcmeant tobot h com plete lyre pre sent theIund.uuc ntal dimensions ofanelectricalcirc uitaswellastherelati onships amo ng the m.Addi tion ally.

thediagramsarcinte ndedtouncove rstudent misconceptionsaboutelectricityand suggcst waysto correctthesemiscon ce ption s.

WhileChe ngandShips to nc(200.\ b ) provide preli minary evidencetosuggcst that thisis aviableandpromisingapproac hto teachingelectricityinthecontextofAvl.cvc!

students(st udentswhoarcfollowi ngtheAdvan cedl.c vclGeneralCertifica te of Ed ucationaspre pa ration for entrance tounive rsit y)intheUnitedKingdom . it rema insto be see n iftheirapproachcan begene ralized to othercla ssro omsitua tions.Thepurpo seof thisstudy istoinvesti gat ethepo ssibilityandutility of theirapproachinasimilar cla ssroom.

1.1Context

At thetimethisrese archproject tookplacc.Lwasteachin gphysics andothe r science course sinahigh school incentra Alberta.Canada.The rewasanoth erphysic s teacherin theschool whohad acted asm~'mentorwhen Ibe ganmyteach ing careerand to getherwe wererespon sible for teac hingallof thephysics students.Ourstudentshad alwaysseemed tohesuccessfu lintheuniton DC circ uits.hut my investigationinto teachingana logies suggested thatwhilephysicsstudentsgenerally couldsucces sfully

understanding orthebehavior orDCcirc uits(Cohen.Eylo u.&Ganicl.I'JX3 ).

WhenIreadCheng and Shipstonc' s (200 3a )paper onAVOWdiagrams.Idecided thatIwouldliketointroducethese diag ramstoa class andinvestigate howthey we re perceivedandado ptedbythestude ntsand the teacher.Inorder10makethisresearch meaningrul.i t wasnecessaryto evaluatethcclfic acyoft hcupproach.Idc ntifyi rs strengthsand weaknesses.and thendecideititcouldandshould beused again.

Inorder tobeable tomakean informeddecisionabout AVOW diagrams .I needed to deter mine:

• HoI\'can theAVOW diagram approachbeusedtoteach about DC circuitsinthe contextoratypicalclassroom'?

• HoI\' dostudents uscAVOW diagramstoreason about DC circuits'?

• HoI\'doAVOW diagramsfacilitateprogression fromsimpletoscientific conceptionsofelectricity?

1.2~lct h()d () l ()g~'

Idecided tousc casestudyasmyresearchmethodology for thisrcsearchstudy.

Yin(200'J)descri besquestionsthatask"ho w'innd"why"as onesthatleadto experiments,histories.andcase studies,SinceIdid notwant todisrupttheregular classroomenvironmentofthe stude ntsinvolved inthestudy.ucascstudyinvolving directobservationseemedtobe.att hesametime.theleastintrusive andthemost informativeapproac h.l-ori hisstudyIrecruitedtheother physicsteacher.Mr.Burns (all

namesreported inthisstudyare pseudonyms),touseAVOWdiagramswithoneof his clusscsandtoallow meto observeand interviewhis students.

Stake(2005)categorizes casestudiesasintrinsic.insrnuncnral. orcollccrivc.

Instrumentalcasestudies attempt togeneralizefrom oneparticulnrc ascaudcollcctivc case studiestrytogeneralize from anumber ofcases.lntriusiccasc studies.ho wever.

focus onsimplyunderstanding aparticular casethatis ofinterest totheresearcher.

The decisionto studyMr. Burns and hisclassinsteadofoneofmy ownclasses wasinformedbyanumberof factors.Pr.mnrily,Ifelt that by observingmy own students,Iwould notbeableto view the.rscof1\VO W diagrams asobjectivelyasI wouldlike. Thesecond reasonwasthat hycollabora tingwith Mr.Burns.Iwouldhe able tolakead vantageofhismany yearsofsuccessful teaching10identifypotentialproblems posed bytheuseof the diagrams.Iwould alsoha ve acolleaguewithwhom Icould discussmy observationsand myintcrprcuuions of theobservationsandothe rdata collected.MyfinalreasonforlIsingMr.HumsclasswasthatIwasnot sched uled to teachanother unitof electricity foranotheryearafter mypreliminaryresearchhadbeen completed.

The datasets usedinthis studywere sununarics ofMr.Burns' andmymeet ings wherewestudied AVOWdiagrams andplannedhowtheywould he incorporated into his unitoncircuits.obser vationsof theclassroomsess ions whereMr.BurnsusedtheAVOW diagramsandadiagnostictestwasadministeredat theendof thelinit todeterminewhich conceptionsthestudentsusedtoreason aboutcircuits. and finally. stude nts we re interviewed aboutsomeof thequestionsonthetest.Intheinte rview.thestudents were

studentsintheintervi ew .

1.3Struc t ureoftheThes is

Chapte r 2sum ma rizeslite ratu re tha tdealswithmisconc epti on s . conc e ptua l modelsor electricity.st ude ntdifficultieswith electricit y. and resea rchonconceptual change .The USl: or analogi esin fosteringconce ptua lcha ng e isdescrib ed and then the AVO W diagramanalogyforteachingDCcircuits ispresented.

Chapter3describ e sthe met ho do logyorthisresearc hstud y .Itbeginswitha

descriptio norcasestu dy researchand thengives a descriptionoftheconte xtof the researc h studyincluding adescripti on or theschoolandsa m ple class.Ithen descri be the wa ythat the A VOW dia gram swereincorporatedintotheunit. Adiagnostictestof studentconc e ptionsof electr icityisused10uncov er st ude nt understanding .and thistest.

DIRECT1.0.isdetailedin thischa pter. The chapterendswith a description ofthe inter vil:wp roce ssusedinlhisrl:sear ch proj l:c t.

Chapte r-Ipro videsthedat ausedtoanswertheresear ch questio ns.Itbeginswith observatio nsabo ut the planni ngandpresentati onofthisunit. These obse rva tio nsarc follo wed by an analysi s of the rl:SUIIS or the DIRECT1.0test.Results from interviews withst ude ntsabo ut theirans we rs10thequesti on s onthislestarc then present ed.Finally.

ther eisa discussionofthe overallconclusio nsaboutthe IISl:or AVOWdia gram sin teachin gDC circ uits.

Cha ptcr :'isulllllla rizes t he resea rc ha nda ns \\'crslhe researc h q uestillns _In this chapterIdiscu ssnot able st re ngthsandlimitation sof thisapproac hand provi des sugg estions for futu reresearch.

Ithasbeenobse rve dthatst udentsdonot often hold expert con ceptionsor1)(' circ uits(Ta be r, de Trafford,& Quail.2006: Tsai.2003) andstu dents'conce ptionsabout elec tric ity donotea sily cha ng e with instruction(MclXmnou&Shaffer.1l)lJ2).It ha s also beenobse rve d that asquickly asthree10fivemonth s afte rseem ing to dcvc lopuccunuc

conce ptio ns. stude ntscanrevert toearlierconceptions(Licht, 1l)l)I ). and c w n incorrec tly recallpreviou s obse rva tio ns in ordertosupporttheirolde rconc e ptio ns(Duit

&Rhonc ck1l)l)X).In thcirinvcsti gat ion ofstudc rusin anelectri calengineering technolo gyprogram.Mc tio ui ,Brassar d.Le vasseur, and Lavoi e(1l)()6) report edthatafte r

fivcscmcs tc rsoffonnalinstru ction.studentsstill rctainedinadequ at c con ccpt ions or curre ntandvolta ge.Eleetr icit y is sccn a s arundamcnt altopic in mostlcv cl solscicncc instruc tio nandyetmany or the fundam ent al conce ptsare poorl y orincorrectl y underst oodandusedhy bothstude ntsand teachers(I'ardh an& Hanu.200 I:Stocklrnuycr

&Treagusl,ll)l)(I).I)cspitc ov crtweuty yca rsorrcscarch.cduca tio n ab olll d cctr ic ily rema insveryproblematic (Mulhall.Mckiurick& Gunston c ,2(01).Applyingthe pri nciplesof con ceptual cha ng e theor ytothe teachi ng and learningofelec tric itymay

hel p toameliorate thesedifficulties.

Conceptualchange isapopu larareaofres earch andseve ra lapproac hes10 enco urag ing conceptualcha ngehave beendcv clopcd.rcstcd .undmod ified.Re sea rc hin this areaisgroundedinaconst ruc tivis tperspec tive,A cons truc tiv istapproachassumes thatlearnersusc knowledgetha t theyalreadyha ve toconstructnew knowledge,Learne rs cons truc t knowledgehasedon whattheyhavebeenexposedtosothatthcycanmake

10

senseofthe irexperience s(Tobin.1<)<)0)."Whenleachingconcept s.as a Iormof com m unicatiou. t hc tea che r mustform anadequate model or thest udc nts wayor vicwiugan idca ands/hc thcnmustassi stthcst udcut inrcstru cturingtho se views tohe mor e adequa te fromthestudc msand fromthe teacher' spcrspe cti\'e··(C onrrey.1')<)0. p.

10<».Kno w ledge isactivelyconstructedby the learne r ratherthanbeingpassi\'ely recei\'edbylhe lea rne r(l'llllG lascrsreld.I<)90),

Thesubjector conce ptua lcha ngeresearc hspa ns allagesorstudcnrsfrom yonng elementa rystudentstouniversi tystudentsand islargel ybased ona concep tua lchange model de velop ed byPosn er.St rike.He ws on.andGcrtzo];(19X2),Accord ingto this conc e ptualchangemod el. itis expec ted thatstudentsarenot hla nk slatesbutruthe rt hat theyhal'epriori dea s aboulp he nome na.lrlhei r undcrsla ndingisatoddswith the

acce ptedsc ientificundcrstundiug.Ihcirconc cpti on may be cha ngcd iu thcIollowi ng manner.Sludenls arepresentedwithaphenomenon thalcannolbee.\plainedbylheir curre ntconce ptio ns and tha tisinconfl ictwith whatthe irconce ptio ns wouldleadthemto beli eve.Thisco gniti ve confl ictisthe nresolvedby presentin g a conce ptio n thatis supe rio r tothestude ntscurren tconce ption s.l-orcxa m plc .st ude nts, whobelievethe unipola r model ofelec tric ity .dono tseetheneed lor111'0wirestoconnect ahulb to a batt er y.Challcugingstudcuts tolight abulbbymuk ingjustonc conncction wirha sing lc wirecangene ra tecogni til'econfl ic l. Wh ilei tis possible tolighta bulb wi thjustone wire.the bulbitselfmustalso beincoutac t withthebatt e ryt o complet cthe circuit .This canbring a bout concept ualchangebecausethestudentsm usl recognize thalthe ir conce ptiondoesnot accountIort hc ir inabil itytolightthe bulb.Thene ll'co nc eptio n .

oldconceptio n in thatitexplai nswhythe bulbcan nothelitwith justoneconnectio n.As lo ngasthenewconceptio n isalsointelli gi bl e and plausible,thenew conceptioncould replacethe prior one,

Ana log iescanbeusedtopresentnewconceptio nsin amannertha tmakesthe new conce ptions unde rs ta nd abl e.believa ble.anddemon stratesthe irutilil )'.Auanalogy

com parestwodifferent idea sb)'idcutifying attri butesthattheyha veincom mo n.The fol lowi ngsimpleanalogydescribestheprocessofteachingamath em at icslesson.

Tcuchi ngales soninmath em aticsislikepaintin g afence.Thesurfaceofthefenceneed s

toheprepar ed inthesamewayinihutstudentsneed10be informedaboutwhattheywill learnand whytheymightneedtolearnit.Thepaintonafence need s10beappliedinan evenmanner without missing an)'spotsin thcsnmcway thatmathI'actsneed tohe presentedinalogi calorder,without omi tti ngan)'importantidea s.The paintmustnotbe appliedtoothickl yoritwi ll notad he re.Amathlessonshouldalsoproceedatapacethat isnottooambi tious.Paintonafenceneedstimetocurej ustasstudentsneedtimeto

processn.:1I' information.Fi nal ly,thefinishedcoatofpaintneedstoheinspectedand any[lawscorrect edinthesamewaythat stud e nts needtoha ve the irknow ledgetested andcorre ctedas required.

Dui t,Roth,Kom or ek ,and Wilhcrs (200 1)outlined therolethaI analogi.:scanpia)' intheprocessofconce ptua lchange.Stude ntsdev el op conce ptua l frameworksasthey incorp oratenewknow ledgeintothei r existi ngknowle dge,Knowledgestruc turesfro m previouslyunderstooddomains canhetransferred tonew domainsbymappingauri hutcs

12

from th<:fa m ilia r domai n lo th<:nO\T lon<:.For<::\amp!<:.slud<:ntswho ar <:familiar wilh th<:lI'aythal pla nds orhi t l h<:sunca nadop tandada pt l ha tconcc ption10und c rsuuuland explai nthewayelectronsmovearoundthenucleu sinRuthcrford'smod cloft hcatoru.

Sinc<:th<:flowof dcclricitythro ughac ircuilcannot bcdircctlyohsc rvcd.

tcachcrsoft cnuscannlo g ics whentheyinstructthe irstudents.Suchana logiescom monly com pare electricit ytoflowi ngwaterorcrowds of people(G entner8:Gentne r.19X3 ).

Osbor n<:(19 X3ldesc rib ed anana lo gytha tcom pa redelectriccurrenttothcIlowofblood carryinghcat toa body"s<:.\trc m iti<:s.T h<:g<:n<:rationand us<:ofanalogi<:sto relate uufamiliarconccptstofamilia ronesiscom mon tomanylearning situatio ns. particularly in thearca oflcam ingsci cnccrDuit.Roth .Konn orck.X;Wilb<:rs.200 Il.l lowc vcr, teachingwithanalogies canCllIS<:diffi cul tiesin ca seswhe re thcunalogybrcaksdown andthebasedomainnolongermapsontothe tnrgetdomainorinsituationswhere students are notsuffi cie ntly fam ilia r withthe basedomain(G lynn . 2(07).Gentn erand Gcnlncr(19X3)described and provideda st udywherest ude ntsa1'<:cucouragcdtousca modelof flowi ngwateramiwaterreservoi rstoexplainCUIT<:nt and batteri es.Attheend ofthe study,the authorsfound tha tst ude ntscametoinco rrectconcl usio nsabOUI electric itybecausethey\\'<:1'<:notfam iliarwit hthewaythai waterand waterrese rvo irs arranged inparallelorserie s affect waterpressureand noll'.

Thisrcscarchst ud ycxum incdtheus<:an an alo gyto<:ncour agcslulkntsto chang<:

theirconceptio nsaboutelectric itytosc ientifically acceptedconce ptio nsofelec trici ty.A summaryofresea rchtha t inform edthis st udy canhebrok endow n intosevenbroad catego ries.Itisimportantto clarifyhow theterms conccption.jn isco nccptio nand

alternateconceptionareused undundcrstoodin resea rchlite rature.Section 2.1discusses the definitions and usesorthetermsmisconception andalternativeconce ption.Students useavarietyor conceptionsinmany areasor sciencebutthe areaor interestinthis projectwas spec ifically how stude ntsconceiveor electricity.Section2.2willdeal with students' conce ptions.misconce ptions. andalternateconceptionsor electricity.Learning about electricity canbeproblematicand the challengesracedby studentswhenlearning about circuitswillhedesc ribedinsection2..1.Thisresearch studyatte mpted tousea conceptualchange approach toteachstude ntsabout electr icity. Section2.4 outlineswork onconceptualchangetheory.One waytoattempt rocncouragccouccptualchange is through theuse oranalogies.Section2.5will describe how analogies can beused to rosterconceptualchange.The spec ificanalogy used in this resea rch projectis calledan AVOW diagram(Cheng&Shipstonc , 2003a) .These diagrams and theiruse asananalog forDC circuitscomprisessection 2.6.Asumma ryorthe resea rchon theuse orAVOW diagrams ispresented insection2.7.

2.1 Dd initi nn nf i\li swn ct'ptilln

There are anumber or termsused in research literaturetodescribetheideas and conceptionsthat students havethat are not the sameas acce ptedscientificconceptions.

Wandersee. Mintzcs.nud Novak (199.:l)listednaivebclicfs.vrroncousidcns.

preconceptions.spontaneo us rcasoning. undpersonalmodels orrealityasexamples or some or theseter ms.Inadiscussionaboutthe besttermIorihisidea.Wandersee.

Mintzcs.andNovak(199.:l)favoured theuseoralternati ve conceptiontothemo re popular uztuvmisconccption,Alternativeconception ispreferred becauseit recognizes

14

theworkthat thelearnerhas alreadydonetogenerate a particular conceptio n.Theterm

conveystheidea tha t theconceptionisratio na landconte xt uallyvalid.Italsoimplies

that thealte rna tiveconceptioncanbe built upontogenerate ascie ntificallyaccepte d conception.Anexampleofthissortofconce ption couldbethatallobjectsin11101ionwill eventuallystop.Thisis atoddswit hthesc ientificconceptionthat obj ects inmoti onwill remai nin motionunless actedupon by anoutside forc e.Thealternativeconceptionis rationa land context ua llyvalidbecausealleverydayob jec tsthat arc in motion will eventua llybeobse rved tostop.Thisisbecausefric tionisalways pre sentasanoutside for cethat actstostopthemotion.

Misconception.onthe otherhan d.im pliesthatther e arcerrorsinthe conc eption

andthattheerrorsneedtohe correc tedor that theconce ptio nmusthediscardedbe forea

sc ientifically acceptedconce ptioncan bedeveloped.Wandcrscc .Ylintzcs,andNovak

(1<)<)-1)suggested tha ttheuscolt hctcnnmisconccptionmiglubeatoddswith cons t ructil' istl'iewso f know ledge.Theseaut horsmak e afurtherdistincti onbet weenthe termslIIi,w'O/I('{'1 J1i!1IIandalternativeconception,Stude nt knowle dge canbe terme da miscon cept ion.(ornaive conce ption.erro neousidea s.precon cepti ons.lim itedor inappropriate propo sitionalhie rarchy. anddifferenti aluptakeofs cience)ifandonly if the knowledge isbeingcompared to asta ndardknow ledge base.When stude nts' under sta nd ingsdonot mat chtheacceptedscientificunde rstan ding.thestudentis cons idered tobe inerrorand thushis/herconception is amisco ncepti on,Inother wo rds.

conce ptionsarc misconcept ion sonlywhenstudents' responsesdonot alignwit h what is consideredtobescientifically acceptable.

Studentsare expo sedtotheworld bothinsideandoutsideor theclassroomand muchorthe waytha t theymak esenseor theworld isnotte stedinschoo l.Studen tsmay never beaskedabo uthowthey thinkorhowarainbow is forme dbuttheylikelyha ve somesortoridea,Whenthis sortolsuulcntknowledgeis stud iedonits ow n term s ,it

should becalledaltcnu uivcconceptions.or alte rna tivefram ewo rks.children's sc ience, com monse nsetheorie s,personal const ruc ts ,and multipleprivate versions orscience, Whenexa m ining how studentsunderstand and explainthcircxpcricnc cswithout com pa risonto acceptedscientificunderstanding,lI/t(,rJllltil'cconccptionisamore appro p ria le ter m thanllli,ICOIIC('/)tio ll,St ude ntshavellli.I('()IIC('ptio ll.l w he n the ir conceptionsdonotmatchthe conc eptionsthattheirtea cherswould preferthattheyhaw, Sincethegoalor thisteachingunitistohav ethestudentsachievethe conceptionor elect ricitydef inedbythe cur ricu lum,thetermmisronrcpti onwillbeused,Howe ve r.

sinceanalternative concep tiononlybecomesamiscou ccpr ionwhc ncomp aredto an accepted anddesiredconceptio n,itisimportant tounderstan dstud e nts'alte rna tive conce ptions,

Wandc rscc etal.(199-!)sum marize d key aspectsor alte rnativeconception re searc h byprese ntingeight kuowl cdgccluims that can be glea nedfromalrcrn. ui vc conceptio n literature:

(I)LearnerscometoIormalscienceinstruction withadiversesetor alte rna tive con ceptionsconcernin gnatu ralobj ec tsandeve nts.

(2) Thealterna tiveconception sthat learn e rsbringtoformalscience instruction cutacrossage-ability,ge nder,andculturalboundar ies, (3)Alte rnativeconce ptionsare ten aci ou sand rcsi suuutocxtinc tion by conve ntio nalleachingst rate gies ,

16

(..l)Alternative conce ptionsoften parallel explanations ofnatu ral phenomenon offeredbyprevious generationsofscientistsand philosophers.

(5)Alternativeconce ptionshavetheirorigins inadiversesetof personal experiencesincludingdirect observationand percepti on.peer cultureand lan guage. aswellasin teachers'explanationsandinstructional materials.

«I)Teachers oftensubscribetothesame alternativeconceptions astheir students.

(7)l.carucrspriorknowled geinteractswithknowledgepresentedin formalinstruction .resultin ginadiverse setofunintended learning outco mes.

pi)Instructional approaches thatfacilitateconceptual changecanbe effecti veclassroom tools.(p,1( 5)

2.2Alte r na t iveCo nce pt io nsofElcct r icitj'

Thewaysthatstudentsconceive of electricityha vebeenthoroughlyinvestig.ucd and well-documented in researchliterature.Stude nts'concept ions ofelectr icity are based onthewaythattheymodelthe behaviourof electriccurrent. Commonconce ptionsabout thewaythat current flowsthroughcircuits arefoundacrossculturesamiages and these conce ptionscan begrouped intobroad categories.Osborne (19li3 ) grouped the conceptualmodelsin the followingmanner:unipolar .clashingcurrents.current attenuation orconsumption.currentsharing.andscie ntificallyaccepted.Thesemodels willbe explainedin the following section.Aschildrengrow. they areexposed to increasinglysophisticated aspects of electricity.As students.they aretau ghtabout electricalphenomenathathighlightaspects of electricitythat challenge theirearlier conceptions.

2.2.1Catcgo r tcs

or

o r

Asc icntifica lly accc ptcdco nccptionof c leciric ityca n be describedbyexamini ng theseq ue ntialmodelsused byst ude nts andidcntifyingthc obscrvntionsand rcfincmcuts tluuaremad etobringthatmodelclo se rtothe acce pte done.Thesim plestmod el isa unipolarmodel.Inthismode l.electri c itynoli' s alongawire fromapowersupplytothe deviceusingtheelectri city.Forexa mple. abulbisconnec ted to abattery asillustra ted in figure2.1.Electrici ty noli' sfromthebatterytothebulb.Ther eisno provisionforthe nowof electronsfromthe bulbhacktothebatte ry.

Figure2.1 .Unipo la r model. Electricity noli' sfrom thebattery10thebulb, Since mostlightsandlam psthat studentsseeareconnec ted toawalloutle t with justonecord . andsince the twowiresthatareinsidethe cor darerar elyshow n to st ude nts. theunipola r model ex pla instheobse rva tio nsmad eat thislevel.

Thenextmodelistheclashin g currents mod el.Itreco gni zesthatther eisaneed fortwocurrentpath s betwe e napowe rsupply and the device usingthe power.Electricity isthoughtofasha vingnegativeandpo sitiveele me nts that meetat the electricaldevi ce and whentheymeet assho w n in figure2.2.theyreleaseene rgy,Thismodel explains II'hy alighth ulh w ill not lightif itisCllnnected tojustone endofahalteryhut musthe connectedtoboth ends.Italsoexplains that electr icaldevicesmusthav e twotermi nals.

IX

There musthe apathlor thetwodifferentcurre nts to lollowsothat theymaymeet insi de ofthe elec trica l de vice.

neqative

~ ~~

curren t

~

Figure2.2.Clashiugcurrc ut modcl.Positive and negati vecurrentmee tsinthe bulband releasesenergy.

Whe nthe ideathatthe re isonlyone kindofc urre nt is prcscntcd . xtud cntsneedto change their conceptionto accom moda te Ibisnew idea.Thethird modeldescrib edhy Osborne (19 83) is anuttc nua tio nmodcl withcurre ntflowinginonlyone direction.The current flow sfromthe batterytothe elect rica l deviceand hacktothebatte ry.Hutif curre nt returnstothebattery . thenthereisno reasonforahatterytobecom edrain ed.

Something mustbe lea vingthe batterytluuiscons ume d bythebulb.Thisresultsin the ideathattheelectri caldevi ce consumesaporti onof the curre ntand that theamountof curre nt flowingintoadeviceisnotthesa me astheamount ofcurre nt thatflo w s outof thedevi ce.Thismodelisfunhcr charuct cri zcdbythclI"aylhatmu llipkdc"icc sinthc circuitconsume current.De vicessuchasmotor s orclemen ts suc hasresistorsthat arc clo ser to thesource or curre nt willconsume mo re currentthandevices orcle mentsfurther fromthesource asshowninfigure2.3.

Oneconseque nceof thispresumed aucn ua tionistha tthis model allowsfor a way todeterminethedirec tion of flow of current.Accordingto thisconception.bulbssho uld

brightest dimm est

l-igurc 2.3.Ancuuati onmod cl. Current isdiminish ed asit passe sthrough eac h hulh. Lesscurrent returnstothebatterythanleaves.

beco me progrc ssivclydim me r the furt heralongthe current paththattheyarc.Howe ver.

thisprogressivedimmingisne ver observe d.Attc m ptin];to reconci le thisobse rvation leadstotheideathatthe clementsor device sinacirc uitactto getherto affec t theamo unt 01"curre nt flowin gthroughthedevice.Thisisthe currentsha ringmodel.This

conce ptio n can be suppo rte d hyusinga batte rytolight anumber01"bulbs connec ted in seriesand thenrever singthepolarity olt hc bnuc ry andobse rvi ngthatthe brightness01"

thebulbsdonot cha ngeuponthis reversal.Curre ntis seentohe equa l throu gheach01"

thecle mentsin the circ uit hut thismodeldiffersfromthescientific oneintha tit is still beli evedthatcurrentisconsume d.

l-inally. thc sc ie ntific modelinc ludestheidea thatcurre nt iscon servedthroughout

thecircuit. The amo unt01"curre nt thatflow sthrou ghthe circuitdepends on the pow er supplyandalloft he clement sanddevice sin thecircuit.Thismodelis sho wn in figurc

2.4.

Themod elsofelec tric ity describ ed above arclimitedto describi ngthewaytha t studentsconceiveofc urrentflowingthro ugh DCcirc uits.However . st ud e ntconce ptio ns ofelectric ityexte nd beyondthedomain01"circuit s and dealwith the idea s ofe ne rgy.

20

power.voltage.resistanceandcurrentand theseideasprovidetheframewo rkfortheir modcls olclcctriciry.

equal brightness

Figurc 2.4.Scientific model.Currentisconservedasit passesthrougheac h bulb aIIII asit passesthroughthe entirecircuit.

Borgesand Gilbert(1999)suggcs tcd thatsuccessful modelsofelec tricity must add ressthe following:

(I)differe ntiationofbasicten usused to speakaboutclcctricity .Iikc currcut. clcctricity andcncrgy:

(2) recognitionof bipolarityof batter ies andothercircuitelements:

(3)recognit ion of thenecessity of aclosedcircuit ifaCUITCIIIisto circ ulate :

(ol)issue oftheconservationornon-conservationofcurrent:

(5)cffectsofclcctrical rcsistancconcurrcnt:

(6)modelsIorc urrc ntcirc ulntio n;

(7)naturc ofclectriccurrcnl.(p.IOO)

Ot hcr lha ll thcscic lllif ica llyacccptcd lllodd ofcllrrClllflow ,1I0llC (1fth c var ioll Slll odds

describedin this sectio nadd resstheseissues completelyandcorrec tly. lorcxamplc.jhc unipolar model doc snot reco gnizethe bipola rity of circ uitcle mentsandtheattenua tio n andsha ring modelsdonotrequirethatcurre nt beconserved.

Furthcrlllorc,lhcscnon-scicnt if ic lllod d sdoll oi cieari y andcorrcct lyddinc cur rcn t,voltagc, dcctric ity ,a ndc nc rgy .Gc ntnc rundGcutncrtlvx.I)reported thatin intcr vic ws.llla ny pco plellla kc uscof agc ncralizcd forc c-a tt rih utc whcn rcasoningahout circ uits.Thisau ributc isuscdtorcprcscntbothc urrc lit, voltage,and powerwithout discrimina tion.A keya spectofthis atrributc isthatitdecre ases asit flowsaround the circuit. Duitand Rhoncck(199X)noted thatineveryday lallguagc,thcwordcurrentis oltcnuscdwhe rethewordcllcr gywouldhesc ientificallymorecorrect.llcllcrand Finley(1992)interviewed pracricin g scic ncctca ch crsabo utelectrici tya ndfoundthat thcytrcatcdc urrcntascnc rgyw hc nc xplai ning and prcdictinglhc hc hav iourofcirc uils.

Thisisinconflict withthesc ientificundersta nd ingwhe re ene rgyis consumedhy cle me nts inthecircuit hutcurren t isnot.Thislackofclcardiffcrcntiutionappearsacross the continuumandisnot cha racteristicofanyparticularmode l.

Onc illlporta nt as pcctof thc na turcof dcc t ricc ur rc nt notspcc ificalIyadd rcs scd hythesemodels isthccau sc-und-etfc ctrelationshipbetween voltageandcurre nt.Itis verycommo nthat thebatteryis SCCII hystudentstobeasourceofconstantcurre nt.

Sludclltsbclic vct hatahattcry w illpro vidc thcsalllc alllo unto f currcnt to ac ircuitwilh onebulbasit would to a circ uitwith two(Hel le r&Finley.1992:Licht,1( 91).Inrcnlity . theamo untofc urrent dep endsonthevoltageolthcbatte ry and theresi stan ceoft he

circuit. Adding ahulhinse rieswill increasetheresistance and thuslowert he current.

Addingabulbin parallelwilldecrea setheresistance andincreasethecurrent.Thc hclicf thatbatteries supply aconstantcurrent maybeheldbystudentsusing anyof themodels of current flow describ edin theprevioussection.

Cohen.Eylon.andGauicl(1<)83) found thatstudentsoften usc currentasthehasis fortheir reasoningaboutcircuitsratherthanvoltage.Inasense.studentssec voltage asa resultofcurrent instead ofasthecause of thecurrent. One exampleofthisiswhen a second hulh is added to acircuit inparallel.Sincethebatterysuppliesconstant curren t.

the current mustbesplit betweeneach bulh.Therclorc.v achoft hctwobulbsreceives halfofthcoriginulcurrentand thuswillbedimmerthanthebulbin theoriginalcircuit.

In rcalit y.thixdocsnothappen andeach bulbin parallelactuallydisplaysthesame brightnessastheoriginalhulh.This conceptioncan bestrongly resistanttochange.

Cohc nctal.(1<)83)discllsseda stude ntwho says"]knowthis Iromcxpcrimcmthatwhen twobulbs arc connectedin parallelto abattery.theirlightisweaker than whenonlyone isconnectedtothesame battery.' (p,40<).

Inorder tounderstandDC circuits.studentsmustmakeusc of amodelthat correctly reflectsthenatureof electricity .As students progress in theired ucationand enco unter electricityin progressivelymoresophisticatedsettings.theirmodelsmust change inorder toaccommodatenewly observed phenomena.A primarystude ntsees thatalampisplugged into a walloutletwith one cordand if the cord isnot pluggedin.

then thelampwill notlight.Theunipolarmodel of electricityis sufficient toaccountfor this observation. Later.twowiresinstead ofone cordmustbeintroducedwhenIhe

elementa rystude nt is givena smallbulbandabaucry and is asked tomake thebulb glo \\' .Whenmor ebulbsandswi tchesareadded tothemix.thest udent needsto beable topred ic tandexplainhowdiffe rentarra ngeme ntsbringabo ut diffc rcutresult s.Addi ng voltmete rs andam me te rsfurt herincrea sesthe dema nds on thestudcnrs mod elof elec tric ity.Unfo nuuatcly.there arema ny obs tac lestobe ove rcome inorderto achievea

com ple teand correct sc ie ntific concepti onofelec tricit y.

2_~ Challen~esinLear ni ngAho utElectricity

Stude ntsfaceanumber ofcha lle ngeswhe n theylearn abo utelec tric ity.These difficultiescan begroupedinto them esthatwill be addres sed in thenextsectio nsof this

cha pte r. Section2.3.\ willexa mi ne thewaythatstudents rea sonaboutelectricit y .while sectio n 2.3.2will present stheway»thatstud e nts interp rettheinformationthat they are givenaboutelectric ity. Section2J .3addresse sthelevel of sophi sticationthat stude nts bringtotheirstudyofelectric ity and the finalsection2.3 ...le xaminesthe\\'aysthat teach erscon ceptu alizeandteac hdectri cit y.

2_1.1St ude n t Rea sonin g

Whe n think ing aboutelectriccircuits .it isim porta nt touseinfor ma tion abo utthe entirecirc uit inorde r to suc cessfully reach cor rec tconcl usio ns.Stude nts donot al\\'ays reason in thishol isticmannerbutinste adwilloftenmak e use ofseq ue ntialor loc al reason in g.Thismeanstha tstudents will focus onsmall parts ofthecircuitand ignorethe circuit asawhole.An exampl e of localrea soningisthat st ude ntswill identifythat add ingaresistorinseries before one bulbwill decr easethebrightness ofthatonebulb buttheywill notident ify tha tit willdecreasethe bright nes sof any other bulbthatisin

seriesaswell.Sequentialreasonin gisdemonstrat edwhen a st ude ntbelie vestha ta rl:si storplacl:dbd or l:abulbwi IIC;llISl:tbl:bulbtodilllbu tthat olll:pl aCl:dalte rabulb will haveno effect.

Seq uential reasoningisalogicalconscq uc uccofIollo wi ngthcau c muu io n modcl.

As identifiedby Shipstone(19X4 l.students beli eve the rearconly"downst rea m"effe c ts.

FOr l:.\alllpk.arl:si storplacl:dbdorl:abul bill a cir cuilw illc;llISl:thl:bulb10bedimmer thall if"it had bl:l:ll plalT d ill thl:c irc uita lk r thl: bulb . Shipston esuggcstcd lhalthis llliSl:OIlCl:pliolllllightbl:lll itigat l:dthrnughthl:u sl: of"atl:achillgallalogy.llcdocsnot.

11l1l\'l:\'n. prnposl:a lla ppro pria tl:01ll:.

Thiswayof"thillkill gabout circuitsi slllo st ckarl yrl:wakdwhl:IlSllllkillsclailll thatswitchesmustbeplacedbefore lightbulbsinordc r tocontro lrhcbulb.While st udents quickl yovercomethatmisconcepti on ,theyhavemoredifficult ywith the ideaof"

addingaresi storbefore oraft eralight bulb. Sl:qul:llIialrl:asonillgc;\u sl:s stlltkntst o predictthat thebriglu ucss ofthebulbshown ill l-igurc 2.5willchange iftheresistan ce of"

resisto r Iischnngcdbutchangingrcsi storZwillhave no effe c ton the brightn l:ss of"thl:

bulb.Thisisbecauseresi st orZ isfoundfurthera longthe curre nt paththan thl: bulb,

Figurl:2.5.Tworesi storsandabulbinseries.

Shipston.:(I<JXX)d.:scri b.:d thisr.:asoni nglob.: us.:dby..\O pnc.: ntofSllld':llts alt e r finishinganadvance dcoursein DC circ uits(a ve rag e ageofIS ), as wellasina

groupof pro sp.:ctiw physic st.:ac hnswhohadgraduat.:d from.:ngin.:n inga nd physics

Duit andRhoncck(!<J<JX)addr.:ss.: dthe issue oflocalrcasoni ug.Whenstudeuts r.:asollthisway. th.:y do llotusuallycollsid.:r llwcircuitasawho I.:rathcr.j hcyfocuson one circuitcle me ntatatime.Whena currentpathsplitsinrotwopath x.xtudc utsassumc thatequalamountsofcurrent travel downeachpathrcgurd lcssoft hcrcsisumcculon g eit herpa th.Astud.:nt usiu gloculr.:asoningw ouldcollt':ll dthal. rorlh.: circuitsho wnin l-igurc 2.6.thecurrent illbran ch Iwouldbethesameasthe curre ntinbran ch2.:\'<:n tho ugh the resistnnccsofeachbranch a1'':not thesame.

branch 1

l-igure 2.6.A combinationcircuit.

Stud.:nts dd.:nd lhisco nt.:ntio nby.:.\plaining thalsinLcckclronsat t hcjunction pointarc unabletoknowthat oneof'thebranc heshaslessrcsistnnccthanthe other branc h.thenthe rcsista nccscun nothaveaneffect onthewaythat the curre ntsplits.The sc icntifically acccptcdconcc ption.ho\\'cvcr. rcasonsin thc follow ing manncr. The

potential differen ces acrossbranchIand branch 2arc thcsalllc sincc anyckc tro n ihat f1owsthrou ghhran chllllustrcturnlothchalteryhal'in gl ostlhc salllc alll oun t of cnerg) in rhccirc uit thathad beenadded toitbythe battery.Thc samc istrucofu nyc lcc tro n thatpasse sthrou ghbranch2.Theamo untofcurre nttha t passe sthrougheach bra nch dep end s onlyon theresi stanceofthe bra nc handthe pote ntialdiIfcrcnccacrossthc hranch.lf thc rcsistanccsarclhcsalllcfor cac hh ranc h.thcn thc cur rc nt throughcach hranchw ill bct hcsalllc.lf thc rcs is ta nccof lhc first bra nc his ha Ifas lllucha sthcsccond brunc h . t he n there will betwiceasmuch current in the firstbran ch asin thesecond.The diffe rencebetwe enthesetwoviewsisthatthescientificallyacce ptedconce ptionreq uires thatthc cntirc currcntpathbc considcr cdwhcn an al yzinga circuitalllil ocairc a soning doc sno t.

Seng upta and Wilen sk y (200<))sugg estedthat novi ces andexpe rtsthinkabout electricityat different levels .Forcxalllpl c .n ol'i ccscon sidercur rcnitobc asubstancc thatflow s andexpe rtscons ide rc urre nt to be thellow ofasubstance.The diffe re nce is thatnovi cesthinkofc urre ntasthingandexpe rtsthinkof itasaproccss.W hc na nov icc karnsthatarcsi st orrcduccscurrc ur. Itiscolllpktclyscnsibictobclic \'c thatth crcisIcss

currentin thepartofa circuitafte rtheresistorthanin the partbefore. Tothc novic c.jhc

curre ntconsumptio n mod clmuk cs sense.Forthe expe rtwho seescurrentastheflowof ckctronsthro ugh thcc irc uit.a rcs isto r rcd uccsthc flowof dcctro nsthroughthe entire circuitand there isuo uuc nua tio u or con sumpti on ofc urrc m.

23.2 St ud e nt Interpretati onandUnd erstand ing

Stude ntsandexpertsuse analogiesto unders tandelectricity.Therearemany analogiesthatare usefulforunderstandingelectricityandsomeworkbcuc rIorparticular situationsthanothers.Thesuccessful useofanalogies alsodependsonacor rect understanding of the baseconceptand the mapping of thebase concept tothetarget one.

For example. when discussingthe behaviourof themoleculesin agas.abilliardball (base)can he usedas ananalogyforthemolec ule(target).Itmust beunderstoodthat hilliard ballsdonot stick together.theyareindivisible. and thattheyreturnto their originalshapeaftereac hcollision.In thesameway. un idealgas doesnotconde nseor chemicallyreact. it doesnotdecomposeintoits constituentatoms. andit isnotpossible todifferentiatebetwee nmoleculesthathave collided andmoleculesthatha venot.They are notdeformedinany way.

Osborne(19X.l)used bloodf1011'asananalogfor currentin a circuitto explain electricity toaneleve n-year-oldstude nt.Inhisanalogy.blood (current)carriedheat (energy )to a coldfinger (gloll'ing bulb)fromtheheart (battery).Bloodmustreturn10 the heart and the amountofbloodin thebodymustremain constant.Thisanalogy worked welluntilthestudent used the analogytosupport his clashin g-currentmodel of elec tricity.In thismodel. the re aretwotypes of current that meetinthe bulband release em:rgy.Thestudent knell'oftwokinds of blood. of oxygen-richredblood ando\ygen- poorblueblood.andviewed themastwodifferentkinds ofcurrent.justlikehisimagined positiveand negativeelectricalcurrent. Thisexampleillustrateshow ananalogycan be

2X

usedto supportscientificallyunaccept a ble concep tio nsorelectric ityift he teache rand stu dentdonotsha rethesameunderstan d ingofthe ana lo gy.

(ientne ra ndC ie ntne r(19X3) as kedstude ntsa houtvario uscirc ui tconrigura tionsas wellasthe ana lo giesthattheyuscto thi nkaboutelectriccircuits.They [oc uscdontwo analogies:theflow ingwaterana logyand theanalog ywhc rc clcctnuisarcrnodcl cdon cro wdsor people mo vingthroughhallways and door s.They round tha tdiffe rent ana lo giesprod uceddiffe rentans wersabo ut thebeha vio uro fel ectri ccirc uits.Theyga ve

auexam pleofo nesubject whousedtheflowin gwater an a!ogy10inferthat thecurre nt thro ugh tworesistor sinparallelwouldhe lessthanthe cur re ntthro ug h [ustonc rcsistor.

He reasone d thatsincethe curre nt flow in gthrou ghthe circuitsplit.enco unte redthe resistors.and the n joineduguiu .ussho w n in figur e 2.7.thatthe curre ntessentia lly encounterstworesistors.Since the curre nt hadtoflo wthrou gh two resi stors .the

resistancemus thegrea te rthan theresi sta nceofo neresistor and thereforewould he less current.The misc onceptionis not unco ve red becausethe model docsnot prompt the st udenttothin kahoutthe curren tsplitting in half wit honehalfofthecurre nt encounteringoneresi sto rand the othe r hal f encounte ri ng adifferent resi stor.

flow ofcurrentisrestricted here

---.<~ ... _1---._.> ... _~---

flowofcurrent is restr ictedhere

FigurcZ.".Arepr e sentation of pa rallelresisto rsusin gaflow in gwat er ana logy.

Thesubj ect wa sthen promptedtothinkabo ut the proble m from amovingcrowd perspec ti ve.lieenv isio ned there sistorsastwoindepe nde ntgutcsina corridorthat wouldallo w peopletopass.lie reali zedthatthisimpliedthatmor epeop le couldpass through thetwo~alesthan could passthro ughjustone.This is sho w nin figu re 2.X.

Corridorwithone gate

Corridor withtwo gates

l-igurc2.X.Movingcrowdsrepresentati onof re si st or sin par allel.Sinc etherearc two differ ent gatesinthese cond corrid orthatpeopl ecanpass thro ugh,twice asman y people can pa ss and thecurre nt istherefor e grea te r.

Thissugge sts that st ude ntsarcahlc touscmorethananalogy10thinkabout circuitsand thattheir choiceof which ana logy10uscaffec tsthe acc ura cyofthe ir

reasoning.

Dupinand Jo shua(19 X9) investi gatedtheuscoftwodifferentana log iesin the contex tof theFre ncheduca tionsyste m.Inthe firstana lo gy . atrainmovesalong a closed track.The tra inha sno engineand the frontofthetrai n islinked tothe back ofthe train sothatthetrai n isthesame length asthe track as sho w ninfi~ure2.9.

30

obstacle

Figur e2.9.Train ana logy.

The reare worke rsinastatio n thatpushthetrain withacons tant forceandthere areobstac lesalongthetrackthat slo wthetrai n . In thisana lo g y.themovementof the tra incarsisthecurre nt,the pushi ng of themenin thesta tionisthebattery .and the obstacles representresi stance.Thisana lo gy de mons tra testhat curre nt is conserve dand thatresistanceatanypoint in the circuitaffec tsthewhol e circ ui t.IIalsodem on st rat e s tha t mor eresi stor swillcauseadecr easein theflow ofcurre nt.This analogy.ho we ve r, doesnotillust rat e or explain parall elresi st ors or voltagebetwee n differ entpo intsin the circ uit.

Toadd ressparall el resistor s. Dupin and Joshua (19 X9)compar edelectriccur re nt toheatflowand are frige rator to abatt ery.Essent ia lly.the refrigeratormainta ins a cons ta nt tempe ratur edifferen cebetwe enthe room and insideoftherefr ige rat or.The tem pe ra ture differenceis analogous tothe pot enti aldifferen cemaint ainedbyabattery.

Resistorsareconcept ua lizedasholesin the side of therefrigerat orthroughwhichheat canflow.'1'\\'0hol e s.liketworesistorsin parall el. allo w moreheattoflow outofthe

refrigerator thanone hole.Accordin gtoDupin andJoshua.theFrenchcurriculum req uiresthat the beha \'iouro f bothseriesa nd parallel res istorsbe add ressed.leither lhe trainanalogynortherefrigeratoranalogydealswithboth ser iesand parallclresisto rs.

One remedywouldbetousebothanalogiesbut the authorssuspecttluu usingtwo analogieswouldbeproblematicforteachersandstude nts.

The need for twodifferentanalogiestoexplainse riesandparallelresistorscan be awkward forstudents.Expcrtsarccasilyu hlc touscanumberofwaysto look ata particularsituationandarc abletoselectanduse thebestanalogyIorthcsituation.

Studcnts.xmtheother hand .arenot asadeptatshiftingbetwee nanalogics asrcq uircdby Iheconl<:XI(Gentner&Ge nlner.19X3 ).

Anotherwaythatexpertsproblem-solving abilities divergefromstude nts' abilitiesisthat expertsareable tocorrectlyidentifywhich factorsarc mostrelevantlo a specificcase(La rkin. McJ)ermoll .Simon.& Simon.19XO).Gutwill,Frederiksen.and Ranney(1996)cond ucteda study in which stude nts were explicitlytaughttousea variety ofp e rspectivestothinkaboutcircuits.Stude nts wereencou ragedto look at the structure of thecircuit,the [low of currentor energythroughthe circuit. and thebeha viou r of the individual elect ronsin thecircuit.Theyfound ihatsllldenisthalused a \'ariet y of perspectivesina concep tualtest on circuitsoutperfor medstudents who didnotxhilr betweenperspectives.

Maloney.O'Kuma. Hicggclkc, and VanHcuvclc n(200 1)constructedasurveyof students' knowledgeofelectricit yand magnetism .Aimedat universitystude nts.the resultsof thissurvey are in accorda ncewithpreviousfindingsin the areaolsrudcnt

32

conceptionsof electricityand magnetism.Whilethis survey doesnot specifica llyaddress electriccircuits. theresult s supportother researchin this area.Of part icularimportance isthecautionthateveryday lan guage andphysics languageofte nuse verydiffe rent meaning sforthesamewordsand thatitisdifficultto control howstudents usethese words.Furthermore .differentteachers can use slightly differentmeanings for thesame words ordilfc rcnt wordsfor thesameconcept (voltageand potenti aldifferen ce .for example).

Shipstonc (I<JX4) ga ve examples or howlanguageca nnlfcc tstudents ideas about circuits.Forexample .onestudentexplains that bulbsinseries willbe eq uallybright becausethey equally share thepowerfromthe power supply.Itisunclearfromthis statementif the stude nt isreasonin g correctlybyrelatin g brightness topower . or if the studentisconfusing powerwithcurre ntand using amodel of electricity where all elementsof a circuiteq uallyshare the currentsupplied bythe battery.Another example shows stude nts referringtovoltage as apropert ythat flowsina circuitruther than as a co mparison between111'0parts of a circ uit.GentnerandGentner(I<JX3)refe rred toa generalstrengthattribute that stude ntsofte nusein place ofcurrent.voltage .andenergy thatseemsto combine elements of theseconcepts.Theydescribe theattribute in the following way:

Peopleininte rviews do appear tohavea kindofcompositestrengthattributethat isinterc hangeablyreferred toascurrent.voltage .velocityof theelectrons.power.

pressure.or force oftheclcctrous.Thi s strengthattribute fails[0obeysteady- state:Itdecreases asthe stuffflowsaround thecircuit. withthe sharpest diminution occurringat theresistor. (p.124)

L1_1S tudrllt Expertiso

Someoft he difficultie sthatstude ntshawwith DC ei rcliitsmightbc auri hutcd to a lackofsophisticationandexperience with respecttoelectricity. lorcx.un plc.xtudcn ts hawlt:s sdirficlilly reasoning qllanlitati"elya nda lgorithmica llyabolltc ircllitsl han the)' dorcasoningqunlitativcly.Studentsalsohavebar rierswhen itcomes tosorting relevant rrom irrelevant inrormation.lna class room settingthis meansthatstlide nts mig ht r\ICliS ononeaspect or acircuit(sllchas cllrrentconservalion) \\,he n thc keytosolvingthe problemmight be adiffe rent aspectoft he circuit(the vollagcacr ossparullclhruuchcsurc eqllal).ln thelaboratory .naYvestlidentsmightrixateo nthes mallvarialionsdlletothe limitationsorthe eqllipmentort heycanmake incorrectobsc rvationsthatsupport their ideasabout thewaytbat circuits behave .Furthen norc.Jthasbeenshown thaI misconcepti onsareremarkabl ypersistentdespiteextensiveinstruction(Mulhall.

McK ittrick&Gunsionc .2(01).

Cohen.Eylon,and Ganiel(19l0) discussed twoaspectsorstude ntdiffi cultywith DCcircuits.Thefirst isthatwhile(afterinstruction) students become ade ptatsoh'ing problemsrelatin gtocurrcm .voltngc .u nd rcsistanccquantit ntivclyinDCcircliitslIsing equations.theyareoft enunable10dosoqualitati vely.Studentslisecompl icated and poorlyunderstood algo rithmstorsolvingcircuits.Iuu do notde monstratc adccp undcrsrandingof whatis actuallygoingon withinthecircuit.l-unh crm o rc. jhcyshow thatstudentsprimarily reasona bolilc ircllitsrromaclirrentra ther than potential differe nceperspective,Cohen.Eylon.a ndGaniel.( I()X3) sllggested thatstudents reliance ona current perspectivefacilitatesmanymisconce ptionsandmisunderstandings

abo ut circuits.Toaddressthese difficu lties.they sugg es t thatitwouldbe wort hwhileto investi gate "me tho ds desi gnedtodeveloptheundersta nd ing of functiona lrel ati on sh ip s betwe e n thevaria ble thaicharacte rize electri c circ uits"(Co he n.I:ylon .&Ganicl, 19XJ.

p.412).

Taber.de Trafford.and Quail(2006) explained sc vc rul factorstha tca n confound stude nt learni ngaboutcirc uits.someofwhic h ha venot oftenbeenaddressedin the literature .Forexamp le.teach ersandothe re xpertsha ve learne d10secphysicalcircuits as sche maticdiagra msandschematicdiagram sasactua lcircuits.Teach e rs seclhalan ammeteranda volt me ter.thou ghtheyhav e verysim ilarappearance s .performdiffer en t

func tions.Teachersknowthatthecolourofawirehaslittle bearing onitsfunc tionina circuit butstude ntsmight not.Fina lly.teach ersmight saythat CUITent readings of 1.9A and 2.0Aarc thesameeventhough they arc clearlydifferentto a stude nt.

Whilestudents donotulways abstractinformati onthesame waythat teachersdo.

they also donot literallyand actually s('('t hings thesame waythat teach er s do .Duit and Rhon cck (199 X)providedanexam ple.re ported bySchl ichting (199I).where a stra ndof highresi stanc ewireglo ws whenconnec te dtoabattery.Studentswere askedtopredict whatpartof the wire (le ft. right. middle . or all) wouldsta rt to glo w first.Despite the fact thatallparts ofthewire began toglow atthesametim e. stude ntsreportedobs e rva tio ns thatmatched their predic tio ns.Thisillus tratesthestre ng thofstudenIS'prior conceptions andtheirinfluen ce on what they learn abo utcirc uits.

Miscon ce ption sper sistevenafte rsignificantins truc tio n.Asano t he rexam ple, DupinandJoshua (19 X7)surveyed the concep tio nsofFre nc hst udentsand found tha t (,0

percentolfourth year unive rsit ysc iencestudentsconside r batte ries10hesources or

2.304Teac her lntlucncesOJISt ud entConcept ions ofElcd r il"it)

Itshould bc scl r-c vidcntlhallhc lI'ay lhattcach c rstal kaboul c k c tric ityand th c conc c ptionsthat tcachc rshold a boutc k ctric ityll'illa rft:c tthcirstudcnts ·co ncc ptio ns.

Shi pstone(19 S-l) propo sedtha ttcnchcrs mightinadve rten tlyreinforc emiscon cepti on sby

thelI'aythattheyspeakabo utelec tric ity.Forexam ple.ateach ermightsay "The current nOll'sout orth cpositiv clt:rminalorthcbattnyhnc,passcslhrou ghthclampLl.thcn splits upat thejuncti onwithsomegoingtolampL2 . andthe rest to thevaria bleresis tor R..."(p,197 )and bynot em phasiz ingtha t thecurrentismo vingthroughall pa rtsoft he circuitatthesametimerathe rt ha n intheste p-wisefashiondescribedbytheteacher.

rcinror cc a sllldcnt's scqucJ1lia lrcasoningprocc ssc s.

Gunsto nc,Mulhall. and McKittri ck (20 09)intervi e wed Austra lia n physics teachers andtex tbookauthors.Thcy roundl hatll' hilcsomc Orlhct cach cr s appr cci att:d thesig nificant difficulti esthat arise II'hcntca chingab oul ckctrici t)' . oth cr sadmitt cd lhal II'hikstudcntshavcdirr ic ultykarni ngthcconccpts,thcy arcnolverydiffi culttoreach.

Thcaulhor s commc ntcd"Wcconrcsstohav ingconsidc rabkdirricultyll'ilhthcnotioll that tcachin gcunbe easywhen itisreco gni zedthatlearningisdirl'icult:,(P.523>.

Addi tiona lly,thc intc l'\,ic lI'ss holl'c d tha tsc\'cralor t hc tcachns ,"understand ings of voltageandrelatedconce pts wereclea rly inadequate."(G uns to nc.ctal.,2009.p. 52-l).

Inintervi ewswith middlescho olscic ncctcach c rs.Pardhanand Ban o (2001 ) discu sscdst:ricsandpara lldc irc uits.Somc orthetcac hc rsuscdcur rc ntCllllsump tio n

models (bothaucuuationandsharinginte rpretations)when reasoning aboutscrics circuits.When discu ssingparallel circuits.almostalloftheteachcrs maintaincdthat add ingmorebulbsinparallel to a circuitwouldnotchangetheamountolc urrc utflowing throu gh thecircuit. Webb(1992)conducteda studywhe re pre-servi ce andin-servi ce primaryteacherswerepresented with fourbasicmodels of electric ity.The mode ls included wereunipolurtw hcrccurrcntonly flow sto.but notfrom. abulb).clashing current(wherethere is apositiveandanegative current thatmeetin thebulb). current consumption(where thecurrentlcaviugthcbulbislessthanthecurrententer ing ).andthe scientifically acceptedcurrentconser \'ationmodel. Theteach erswere asked toselec t whic h modelbestrepresentedhow theyviewedelectricity.Lessthanonethird ofthe teachersselected the scientifically acceptedconce ptionoftheflow ofcurrent througha circuit.Ilowe \'er.after nperiment ingwithbulbs.LaucricsandammetersandI'ollo winj;

a teachingseq uence descr ibedbyCosgroveandOsborne (19X5). thepercentage of teacherschoos ingthe scientificallyacceptedconce ptionincre asedto greate rthan eigilly perce nt. This suggests thatwhile teachersmaynotha veaccep ted concepti on s of electricity, theirconce ptionscanchange.Thechallengeistofind waystohel p fosterthis conce ptualchangeinstudents.

2AResearch1111Cunce pt ualChall~l'

Ed uca tionalresearch regardingconceptualchange in the past haslargelyfocused onscience concept s and inparticular.thedomainofphysics (Duit,200(,;Grayson.

2( 04).Researchbeginnin gin theI970 sconsisted ofinvestigating students'pre- instructionalconce ptions,This areahasbeenthoroughlystudiedand researchhas shifted

tolookingat thl: l11l:c hanisl11sofconcq)l ualcha ngl:.as \\'d lasintc rvcnt ioustluu might encourageconce ptualchange,Thissection wil lrevie wworkonconceptualchangeand thl:suh sl:qul:ntsl:ction \\,ill d iscussthl: usl: of analogil:stol:ncouragl: concqJlu alchangl:.

lA .1Concept ualChang!'Frumewnrk

"Accom modationofa sc ie ntific conce ption:Towarda theoryof conce ptual cha nge"byPosner,Strike, Hewson.andGertzog (19li2) forma lizedtheproCl:SSof confrontingstudentswithdatathatwasatoddswiththeirpriorconcl:ptions,lt\\'as believedth.ucoucc ptualchangewouldoccur ifstudcnIs cxpc ricnccddisx.uisfuctionwith thl:irCIIITl:nt concl:ptiona nd\\,nl: prl:Sl:llll:d \\,ithana ltl:rnativl:co nCl:IJlion that was intelligible,plausihlc.nnd fruitful.For anewconceptiontobe intclligiblc.jhcstudent I11UStbe ableto understandthe newconce ption.Plausible concep tio nsmustbe believab le and thenew conceptionsI11USt be fruitfuliftheyareto allowstudentsto developnew knowledge abo ve andbeyond whattheywere able to atta in with their prior conce ptions.

Itwasexpectedthatthe inte lligibility criterion mustbemet priortoplnusibilityaud plausibilitypriortoIruitfuln css.Posncr . ct al.(19li2)expectedthat the oldconce ption andthenew conceptionwouldnotcoexistand thaithe changewouldhe a sharpone.

This approach to concept ualchangeprovidedthe basisforman ystudies onconceptual change.Rl:sl:archl:rs l:,\palllll:donthisapproac hand applil:dit tomanyd ifferent situations and contex ts.

For example. Wand ersee ,Minizcs.andNovak(199-l) analyzedseveralof these conccptuaIchange studies andsuggl:stl:dthat teachingapproachesbased onconce ptual

3X

changetheor yarcmorccfri cicntthan othertcaching app roach cs.Duiland Trcagust (2003)echoed thisconcl usio n.

Despitethis appa rentsucce ss .thereappear to belimi tatio ns on theclassical conceptua lcha ngcnpproa ch.Conceptua lcha nge approacheshave solurhccnla rgcl v restr icted to spc ci ficarca s of scicncc contcnlsuc haselectri cit y andforces.The areas of investigatio narcsma ll when compared10possib le area s ofi uvcs tig.u ionthat might inc ludesc ie nce-technolog y-s ocietyconcern s suc h as globa l warming.biodivcrsitv .noise pollution.and radi a tion risk (Fcnsham2( 0 1).

2.4.2Expanded Views ofConcept ualChange

Eve n withinthisnarr owconte xtofspeci ficsc ie nce dom a ins .research perspect iveshave also expandedwithrim e.Conce ptua l changewas once look ed at lrom justarat ion alandclinica l perspecti ve.Fromthisper specti ve,factors suchas students learningintcmionx.motiv.uions. undlearning situa tio ns were ignored.Laterresearch, however.examine d thesefactorsas well.Descriptionsof learningcnvironmcutsthat prom ote conce ptualcha nge. uswellas sugg es tio nsandguidelines fordcsign in gthese cuvironmcntsarc becomin gmo renoti ceabl e.An exampl e of thisisprovidedby Vosniadou.Ioannidcs. Dimitrak op oul o us . and Pa pad cmctri ou(200 1)where the aut hors recom me nde d limitingthe breadth ofcurric ulum.cons ide ringtheordero fi nstructionof parli cular concepls.con siderin g studc nts·pri orknowledge.facilit atingmetaconc epl ual awar e ness.addressing students'priorconceptions.mo tiva tingforconceptua lchan ge.

produ cin gco gnitiveconflict,and providingmodelsandexterna lrepresentati on s.

The natureof conceptual changehasalsobeen refin ed.Itisnolongcrsugucsrcd Ihatstudentsshould discardtheirold conceptionsand ithasevenbccnsuugcstcd that

perhapstheyshould notdiscardthem(Smith.r liScssu.&Roschell e,1993: Ty son, Vcnvi llc .Harriso u&Trcagust.1997).Taoand Gunstonc(1999)showed thatstudents who holdalternative conceptionsmightchangethoseconceptions whenfacedwith conceptualconflic tinone contexthutthattheymay revert totheir orig inalconceptio nin anothercontext.The conceptualchangemodelrecognizesthe importanceofstudents priorconceptionsand concedestheirpossibleutili tyfor interpretingtherealworld.An exampleof this would he whenaphysicsteacherint rod ucesstudents10Newt on'sFirst I..all" of Motion.Studentsusuall yremain uncouvinccdthatanobject in moti onwill

remain inmotion ifthereisno (net) force acti ngonit.Thisisbecauseinalloftheir experience,cvcryrhing thatisin motioneventuallycomestoastop.Their conceptionof motion hasmuchmoreutil ityin thereal worl dolbicyc lcs andskateboards than Newton's idealized uni verse-w ithout-frictionwhere objectskeepmovingeven though there isnoforce actingon them . Thus,different andeven conflictingconcepti ons can he heldat thesametimeaslongasthestudentisconscious of thecontextinwhich theyare applicable .

Furthermore,conceptualchangeisnowbeli eved tohea gradualratherthan

suddenprocess(Tao&Gunstonc.1999:Vosniado uctal.. 200 I:Vosuiado u.2( 03).A newconceptiongai ns statusasitprovesitselfagain andagaintohesuperior toaprior conception.Thisideahasimportantramif icatio nsfortheuse ofconceptualchange approachestoteaching.Forexample,it isnot suffi cient to showsiudcmsjustonce tluu

40

thcirconcc ptions ar cnotadc q ua tc.hut rat hcrstudc nt m isc onccplionsm usthccha llengcd againandagainandshownto he inerror.

Anotherfocusofconceptualchangeresea rchisthc cxamiumionoIst udc m s mct a-conccpt uulawareness (Q ian. 2000:Ty sonctal..IlJlJ7 :Vo sniad ou ctal..2( 01).It appea rsthatwhatstudents thinkaboutknowl ed geand learnin ginfluen cesthe succ cxsor failurcof diffcrc nttcachingapproac hcs.ltishcl ic\'c d lhatconcc ptualchangcis cnhanccd whcnst udcntsarcmadcconscious lyawarcofthc way thatthcy arct hinking andrcas oningahoutaconccpl. w hythc y ar cthinkingand rcas oningthaIway .andwhat thclilllitations of t hc ir thinking andrcasoninglllight hc.

St udents 'motivation sintheclassroom alsoneedtobe consideredinthecont e xt ofconceptualchange (Pintrich, Man.& Boylc .llJlJ3).FOr C\ alllp le.whethcra slUdcnl ·s moti\' ationforlcarn ingisinlrinsicorntrins ica ffcc tst hcprocc ss ofconcc ptua lchangc hyinfluc uci ugthe aucntiouthatst udentsgivetonewinform at ionand themcracogni tivc st ratcg icst hallhcy cm ployloattcmpt toundcrs tandthat ncwinformation.

2.·L \Conce ptualChangeChallengesilltheClnssru nm

Itha sbeensuggestedthatanom alousdata isnottheonlystrategythatisuseful for instigati ngconce ptua lchange.Conflictbctwccna studcnt'scon ccption s and scicntifically accc plcdconccptions m ight bc in\"(lkcd throughthcusc of analogics.

metaphors .and discu ssion (Limo n.200 1:Mason . 2( 0 1)

Duitand'lrc agust(2003)identi fiedtheincorpor ati onofc onceptualcha nge

researchintoteachingpracticeasanarea innccdofIu turcwo rk.Conceptualcha nge rcscarch frollla cognit i\'cpsychological perspccti\'c . a s opposcdto atcac hi ngand