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KINDERGARTEN'OPTICSManuelF.
M.
Costa,JúliaCampos,MadalenaLira,SandraFrancoUniversidadedoMinho,DepartamentodeFísicaTel.
+351253604070;Fax.
+351253678981e-mail:mfcosta@fisica.
uminho.
pt4710-057BRAGAPORTUGALABSTRACTTheintroductiontoourschool'studentsofthewondersoflightandopticsanditsunderstandingcanandshouldbemadeasextensivelyaspossible.
Assoonasatkindergartenlevel!
Ahands-onapproachleadingthestudentstoobserveexperimentanddiscoverthemselvesinacriticalcommittedandactivewaythedifferentaspectsoflightandopticsshouldbeemployedatallschoollevelsandmustbethemaindrivingpedagogicalpracticeofalllearningprocessofscienceandtechnology.
Inthiscommunicationwepresentaseriesofexperimentsandsupportmaterialdesignedinthishands-onperspectivetobeusedtointroducethestudyofopticstokindergartenandearlybasicschoolstudents.
Acriticalevaluationofthefirstresultsoftheapplicationofthesematerialwithstudentsaged4to10yearswillbepresented.
1.
IntroductionYoungchildrenarealwayseagertolearntoseenewthingsbutalsotoknowandtounderstandtheworldthatsurroundthem.
Withreduced"pre-knowledge"usually,therearenopreviouslyacquiredmisconceptionsorevenprejudices.
Alsotherenoexamstostudyfor…"just"theinnatesurvivalneedtoknow.
However,sincetheywerebornapermanentlearningprocesstakeplaceatanextremelyfastpace.
Childrenlearnfromtheenvironmentfromwhattheyfeelfromwhattheylive.
Aswecouldseewhencontactingchildreninthisagerange,4to10yearsold,aconstantreferencetotheireverydaylifeandpreviousexperiencesismade.
Hands-on[1,2]activitiesarefundamentalandthe"natural"approachfortheseyoungstudents.
Thefirstconcernoftheeducatorshouldbe,withthisclearperspectiveinmind,toshow…orbetter…toletthechildrento"see",toobserve,toconfrontthemselveswithnewobjectsprocessesandsituations.
Timeisfundamentalandshouldbegenerouslygiventotheyoungstudents.
Ofcoursesome"pressure"canbeuseful…induetime…respectingeachonespace.
Fromearlykindergartenyearsthechildrenshould"learn",shouldbeleadtoworkingrouptointeractandcooperatewithpeerstowardsacommongoal.
Carehowevershouldbetakenbytheeducatorinordertoensurethateachstudentwillhave,inthesegroupactivities,theneededtimetoestablishtheirown"knowledge"whileguarantyingthatnochildren,apparently"faster",feelsuncomfortable"waiting"fortheothers.
Nosenseofsuperiority,orinferiority,orevenofcondescendence,inthiscompetitionprocessthatalwaysappearsinthesesituationsattheseages,shouldberewarded.
Yetfundamentalitisthattheeachchildunderstands,stepbystep,theimportanceof"cooperation",oflisteningtheotherlettingtheotherstoknowofourfindings,helpingandacceptingtobehelpedinthesakeofacommongoal.
Howtodothat…aPortuguesepopularsaying(certainlywithequivalentsthroughouttheword!
)"wordsaresilver,silenceisgold"…bepatientgivetimetothestudents,andtoyourself…,openwidelyyoureyesandleadthewaysmoothlyaffirmativelyanddiscreetly.
Wordsmightbemadeofsilverbutitisfundamentalthatthechildisabletoverbalisecoherentlytheirfeelingstheirfindingstheiropinions.
Hands-onshouldbecomplementedwithaconstructivist[3]approachandotherslikeconstrucionism[4]andconceptuallearning[5].
"Always"hands-onbutnotblind/mechanically…"…dothisandthenthatandthatand…"Learningisdiscovering…bythestudent…himself…activelyandreflexively.
2.
LightandopticsatthekindergartenBeingrelatedtooneofourmainsenses,beingtheeyesamajorgatewaytotheworldthatsurroundus,lightrelatedphenomenaareratherappealingtoyoungchildren[6].
Youngstudentsreadilyrealizetheimportanceofseeingandtheroleoftheireyesandoflightsources.
Theyareparticularlyattractedtothecolourphenomena,toreflectionandtransparency,toshadeandchangesinluminosity…Belowwepresentasetofsimpleexperimentsthatwedesignedfor4to10yearsoldstudentsandthatmayserveasbasisforteachersandeducatorstouseintheirclassroomsandininformalactivities[7].
Wedividedtheexperimentsinthreeparts.
Afirstoneintendstointroducetheroleoftheeyeand…weneedlighttoseeobjects.
Atthesecondpartweintendtoshowusingasimplemodelhowtheeyeworks.
Finallythethirdpartdealswithlightandcoloursandisbythemostattractiveoneforouryoungscientists.
3.
Lightandopticsexperimentsinthekindergartenandelementaryschools3.
1Part1.
Themainconceptbehindthisfirstsetofexperimentswas:weneedlighttoseeobjects.
Theexperimentsweredesigntoshowthat:Weseeanobjectbecausethelightfromtheobjectenterstheeyethroughthepupil.
Constrictionofthepupillimitstheamountoflightenteringtheeye,anddilatingofthepupilallowsmorelighttoentertheeye.
So,inbrightlight,thepupilconstricts,andindarkness,thepupildilates.
(Experiment1)Thereareobjectsthatemitlight(ie,lightsources)andothersthatreflectlight.
(Experiment2)Lightisreflectedfromthesurfaceofobjects.
Darkobjectsreflectlittlelightwhilewhiteobjectsreflectmorelight(Experiments3and4.
Figure1.
).
Experimentn.
1.
PupilobservationBackground:Thelightenterstheeyethroughthepupil.
Thepupilhastoadapttodifferentlightintensities.
Method:Thechildrenaredividedintogroupsof2or3.
Theroomlightisdimmedandpenlightsaredistributedtoeachgroup.
Itisaskedtooneofthechildrentoilluminatehis/hereyeswhiletheothersobservethepupilclosingdown.
Experimentn.
2.
Luminousandnon-luminousobjectsBackground:Thereareobjectsthatemitlightandothersthatreflectlight.
Method:Theroomisdimmed.
Lightemittingobjects(ofdifferenttypes)andnon-luminousobjectsareavailableandareshown.
Thesimilaritiesanddifferencesbetweenthevarioustypesoflightsourcesandobjectsarediscussed.
Experimentn.
3.
BrighteranddarkerobjectsBackground:Thelightisreflectedfromthesurfaceoftheobjects.
Thedarkobjectsreflectlittlelightwhilewhiteobjectsreflectmorelight.
Method:Severalobjectsofdifferentcoloursareplacedinablackboxwiththefrontfaceopen.
Theroomlightisdimmedleavingonlyasmalllampbehindthebox.
Thepositionofthelampisgraduallychangedtoallowsomelighttoreachtheobjectsinsidethebox.
Astheinsideoftheboxbecomesmoreilluminatedthedarkerobjectsbecomeprogressivelymorevisible.
Experimentn.
4.
LightreflectedbyobjectsBackground:Thelightisreflectedfromthesurfaceofobjects.
Thedarkobjectsreflectlittlelightwhilewhiteobjectsreflectmorelight.
Method:Inaverydarkroom,eachchildplacehimselfinfrontofamirror.
Onehandholdsapenlightononesideofthefaceinordertolightenthenose.
Thechildisaskedtoobservehis/herfaceinthemirror(figure1.
).
Figure1-Thelightreflectedbytheobjects'experiment.
Theexperimentisrepeatedbyholdingawhitecardboardwiththeotherhand,paralleltothesidenotilluminated.
Theprocedureisthenrepeatedbyreplacingthewhitecardboardbyablackoneandthenbycardboardsofdifferentcolours.
Finallythestudentreplacethecardabyasecondmirror.
Childrenrecordanddiscusswhattheysawhappeningonthenon-illuminatedpartoftheirfacewhenusingthedifferentcoloursorthesecondmirror.
3.
2Part2.
ThemaingoalofthesesetofexperimentsistoillustratehowoureyeworkTheexperimentsweredesigntoshowthat:Howtheimageofanobjectisfocusedontheretina.
(Experiment1)Whatisaccommodation.
(Experiment2)Seeing"bad"…Whatismyopiaandhyperopia.
(Experiment3)Thesesetofexperimentswereperformedwithamodelofthehumaneye(figure2.
).
Figure2-HowtheeyeworksexperimentsExperimentn1.
Usingabrightlightsource(acandlemaybeusedunderteacherssupervision),imagescanbefocusedonthemodel'sretinasimulatingthehumaneyeimagingmechanism.
Experimentn2.
Todemonstratetheaccommodationthelenscanturnthickerorflattertofocustheimageontheretina.
Thelensisachamberconstructedofopticallyclearsiliconeelastomerconnectedbytubingtoawater-filledsyringe.
Waterforcedintothelensincreasesitsthicknessandcurvature;withdrawalflattenstheprofileofthelens,changingitsfocus.
Experimentn3.
Theeyemodelcansimulaterefractiveproblems(thatsomechildrenmaysufferfrom).
Myopiaandhyperopiacanbesimulatedbychangingtheeyes'shape(length).
Itisalsopossibletousecorrectivelenses.
Wheneverthereisachildusingspectaclesitmaybeusedtoillustratethecorrectioneffect(iftheteacher/educatorisnotconfidentenoughwiththeprocess,isprobablybettertoskipthisstepunlesssomestudentspointsitout(whichoftenhappens…fortunately…).
3.
3Part3.
Colouristhemainconceptaddressedatthislastsetofexperiments.
Theexperimentsweredesigntoshowthat:Itiseasytoseparatewhitelight'colours(Experiments1and2).
Wegetwhitelightbyaddinggreen,redandbluelight(Experiment3).
Gettingyellow,magentaorcyancolours(Experiment4).
Object'colourdependsonthelightreflectedfromthem(Experiment5).
Experimentn.
1.
Whitelightdecomposition1.
Background:Whitelightis"composed"ofallthecoloursintherainbow.
Method:Usingabrightwhitelightsource(placingaslitinfrontmayhelp),abeamofwhitelightisprojectedontoawhitesmoothsurface(target).
Withadiffractiongratingand,or,aprism,thelightisdecomposed,projectingthelightspectrumonthetarget(itmaynotbeeasytogetallcoloursclearlyvisible…childrenmustlearntobepatientandresilient).
Colourfiltersareplacedinfrontthebeamand,asalways…,discussed.
Experimentn.
2.
Whitelightdecomposition2.
Background:Whitelightis"composed"ofallthecoloursintherainbow.
Method:CDsaredistributedtothechildren.
Theyobservethedecompositionofsunlight(theceilinglamporeventhelightemittedbyacomputerscreen)intotherainbow.
Theexperimentisthenrepeatedwithapocketspectrometer.
Experimentn.
3.
and4.
Mixinglightwithdifferentcolours.
Background:Addinggreenredandbluelightallowsustogetwhitelight.
Method:Threelightsourcesareused-onered,onegreenandoneblue(simpleflashlightswithcolourfilter–theteachermustcheckaheadhowredisthered,howgreenisthegreen…).
Thethreebeamsaredirectedtoonepointofasmooth,notpolished,whitewallorboard.
Childrenarealsoaskedtomakeshadowswiththeirhands(figure3.
)andnoticeallthecoloursobserved.
Theexperimentisrepeatedwithonlytwolampsconnectedatatime.
Theconceptofsubtractivecolourmissingmayalsobeaddressed.
Figure3–Colourshadows.
Experimentn.
5.
Background:Thecolourofobjectsdependsonthelightreflectedfromthem.
Method:Thisexperimentisdoneusingthesamelightsourcesusedbeforeandatthesamepositions.
Severalcardboardpicturesofdifferentcolours(thecardboardshouldnotbeshiny)areplacedonablackboard(figure3).
Thosecolourcardsareilluminatedwithoneofthelampsandrepeatedwitheachoneoftheotherlampsandcombinationsofthem.
Attheendthethreelampsareswitchedon.
(Especiallyforthesetwolastexperimentsitisnecessarytodimsignificantlyroomlights).
4.
BriefdiscussionandconclusionWedecidedtoinviteagroupofelementaryschoolstudents(ages6to10yearsold)totheuniversityinordertoperformthesesetsofexperiments.
Theactivitywasrathersuccessfulpleasingtostudentsandteachers.
Althoughstatingtheirclearpreferencethatthecolourexperimentswerethemostpleasantones,theresultswereingeneralverypositive,duringtheexecutionitselfandinthefollow-upactivitiesundertakenbackattheschool.
Figure4.
Demonstrationsandvisitstomuseumsandsciencefairsmightbeveryusefulifafollowupworkispreparedbytheeducatorandconductedinclassroomcontext.
Follow-up,infact,shouldalwaysbeconsideredveryimportant.
Thesenon-formalorinformalactivities(visitstolabs,museums,sciencefairsorlectures,figure4.
)shouldalwaysbefollowedofworksessionsintheclassroomexploringthemotivationachievedanddevelopingandorstrengtheningtheknowledgetransmitted/acquired.
Attheendofouractivityaseriesofenquiriesandquizzesweredeliveredtotheteachersandaskedtobereturnedforanalysisandstatisticaltreatment.
Furthermorewedistributedtothestudentsmaterialandshortguidelinestobuild,ontheirown,akaleidoscopeandasimplepinholecamera(amuffinaluminumcup,arubberbandandasofttranslucentpapersheetisenough…).
Beingclearforusthatthestudentseasilyandcorrectlyareabletounderstandtheimportanceoftheeyeintheprocessofseeing,wedecidedtoexplorealittlebitthevisionprocess.
Weusedasimplemodeloftheeyewithapupil,arubberlensthatcouldbeinflatedusingawatersyringeandaretinalikedisplaceabletarget,whichcanbeeasilybuilt.
Weexpectedthestudentstohavedifficultiesinunderstandingtheprocessorevenacceptingit…wewereinsidetheeye…!
Infactonlyolderstudents,9to10yearsold,wereabletodealwithit.
Figure5.
Shapesandcolours.
Theagespancovered,4to10yearsold,isratherlarge(especiallyasdealingwithchildren).
Onemustcarefullycopewiththedifferences…beingflexiblebutalwaysobservingchild's'reactions.
Fromveryearlyagesyoungchildrenarestronglyattractedtocolours,inparticulartobrightprincipalcolours,arefascinatedbythewondersofcolourmixingandtheyseemmoreattractedtoadditivemixingoppositetowhathappenswithschoolstudentsthatbeforebeingpresentedtotheissuehadpreviousexperienceinmixinginkforpaintings(thesubtractiveprocess).
Thehands-onmanipulationofcolourcards(especiallyifbeingpartofgames)isparticularlyeffective(figure5.
).
Ingeneralthebasicconceptcoveredbytheseexperiments(speciallypart1and3)arereadilyunderstoodbytheyoungchildrenthatimmediatelyafterrealizingtheconceptpresentaseriesofexamplesrelatedtotheirownexperience(…whenelectricityfailedandlightswentoffIwasafraidmymamaleavemealoneinthedinnertable…).
Thistypeofreactionhappensquiteoften(normallyolderstudentsaremore"careful"expressingtheirfeelingsandideasandrestrainthemselves)andisagoodindicationthatsomelevelofunderstandingoftheconceptwasachieved.
References1.
"Hands-onScience";CostaMFM;SelectedPapersonHands-onScience(ISBN978-989-95336-2-2);CostaMF,DorríoBV,MichaelidesPandDivjakS(Eds.
);AssociaoHands-onScienceNetwork,Portugal;pp.
1-13(2008).
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GattS.
(ed.
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"LearningOpticsatBasicSchoolsbyExperimentation";CostaMFM;SelectedPapersonHands-onScience(ISBN978-989-95336-2-2);CostaMF,DorríoBV,MichaelidesPandDivjakS(Eds.
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25-28(2008).
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ManuelF.
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Costa,Hands-onIntroductiontoOptics/Introduoàptica(bilingualedition),Hands-onScienceNetwork,ISBN9899509523,September2006.