Teacher’s Guide for: Solar...

Contents: Quick Reference Sheets:

• Intro:Fresnel Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page2• Experiment1:Experimenting with Magnifying Lenses . . . . . . . . . . .page3• Experiment2:Burning Things with Magnifying Lenses . . . . . . . . . . .page3• Demo1:Try to Burn a Fire Brick . . . . . . . . . . . . . . . . . . . . . . . . . . . .page3• Demo2:Burning Things with a Giant Fresnel Lens . . . . . . . . . . . . .page3• EquipmentList . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page4• Story,Part1:Jack and Jill are Ant-Size . . . . . . . . . . . . . . . . . . . . . . .page5• Story,Ending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page6

Video Transcript:• Intro:Fresnel Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page7• Story,Part1:Jack and Jill are Ant-Size . . . . . . . . . . . . . . . . . . . . . . .page9• Experiment1:Experimenting with Magnifying Lenses . . . . . . . . . . page11• Demo1:Try to Burn a Fire Brick . . . . . . . . . . . . . . . . . . . . . . . . . . . page11• Experiment2:Burning Things with Magnifying Lenses . . . . . . . . . .page12• Demo2:Burning Things with a Giant Fresnel Lens . . . . . . . . . . . .page13• StoryEnding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .page15

Teacher’s Guide for:

Solar FurnacesNote: All activities in this document should be performed with adult supervision. Likewise, common sense and care are essential to the conduct of any and all activities, whether described in this document or otherwise. Parents or guardians should supervise children. Rock-it Science assumes no responsibility for any injuries or damages arising from any activities.

Note: All activities in this document should be performed with adult supervision. Likewise, common sense and care are essential to the conduct of any and all activities, whether described in this document or otherwise. Parents or guardians should supervise children. Rock-it Science assumes no responsibility for any injuries or damages arising from any activities.

SolarFurnacesARock-itScienceLessonFilmedJuly,2009

Title Page of Video

NOTE: This is the transcript of a lesson that was videotaped during an actual Rock-it Science class with real students, not actors. The students’ brainstorming comments are included on the video but are not transcribed here because they’re not part of the lesson presentation.

Rock-it Science2110 Walsh Ave, Unit FSanta Clara, CA 95050www.rockitscience.org

(c) 2012 Rock-it Science Educationally Useful Programs. All Rights Reserved

Rock-it Science Teacher’s Guide Solar Furnaces -- Page 2

Intro Quick Recap:

• Inthedaysofsailingships,theyneededawaytowarnshipssotheywouldn’tcrashontheland .• Theytriedvariouskindsofsignalfires:candles,bonfires,glassenclosures,whaleoillamps .• Fresneltookacurvedlenseandmadestairstepsinitsoitwaslighterandwouldn’tbreakaseas-ily .

• Thenheusedseparatepiecesofglasstomakethestairsteps,whichimprovedthequalityofthelens .

• Instructordemonstratesvariousfresnellenses,showinghowtheymagnifyhisimage .

Lesson Intro: Fresnel Lenses

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Demos Quick Recap:

Experiments Quick Recap:

• Studentscolorasheetofpaperwithpermanentmark-ers,usingsomelightandsomedarkcolors .

• Outside,studentsusesunlightandamagnifyingglasstoburnthepaper,thenadryleaf,thenawetleaf .

• Remindstudentstokeepthespotofsunlightassmallaspossible .

Experiment 2: Burn Things with a Magnifying Lens

• Studentseachgetahandheldmagnifyingglassandlookateachotherthroughthemtoseehowtheimagechanges .

• Studentsgetafresnellens(1lensperpairofstudents)toexperi-mentwith,incombinationwiththemagnifyingglass .

Experiment 1: Experiment with Magnifying Lenses

Demo 2: Burn Things with Giant Fresnel Lenses• Outside,Instructorsetsupapairofgiantfresnellensesmountedonframesandusessunlighttoburnapieceofwood,awetsponge,amarshmallow,apennymadeofzinc&copper,apennymadeofcopperonly,apieceoflavarock,andafirebrick .

• Instructorusesapropanetorchburningatapprox .2,000degreestotrytoburnafirebrick .

• Thebrickgetshot,buttheflamedoesn’tdamageit .

Demo 1: Try to Burn a Fire Brick

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Equipment List: “Solar Furnaces”Items needed for Instructor:

• GiantFresnelLensesfromprojectionTVs,mountedinadjustablefreestandingframes

• Clampstoholdlensframesinposition• Bathtowelstocovergiantlenseswhennotinuse

• Medium-sizeFresnelLenses,withvariousmag-nifications

• OilLamp• PropaneTorch• Propane• FireBrick• Metalstrap,rods,andclampstoattachfirebricktolensframe

• Welder’sMask• Tongs• Thingstoburninthefurnace:wood,marshmallow,sponge,pennies(purecopperandcomposite),lavarock(pumice)

• 12-ozClearPlasticCup• Water• RollingCart

Items needed for Students:

Consumables (per student):

• 12-ozClearPlasticCup• Water• SheetofWhitePaperOther:

• MagnifyingGlasswithhandle,approx .4”diameter• Lens,fresnel,plasticsheet,1per2students• Markers,Permanent,Colored• Welder’sGoggleswithflip-downlightshield

Prep Work:

• Washgogglesbeforeclass• Cleanmagnifyingglassesandlenses• Assemblegiantfresnellensframes(Thelenscomesfromanoldprojec-tionTV .ContactRock-itScienceforinformationaboutbuildingthewoodenframe .)

• AttachFireBrickstolensframes• Checktheweather(sunlightrequired)

Welder’s goggles with flip-down light shields.

Story Recap: “Jack and Jill are Ant-Size”

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Part 1:

• JackandJillhaveshrunkthemselvesdowntothesizeofanant .• They’reridingtheants,havingantrodeos,ridingthroughthebladesofgrass,etc .• Thedecidetogoandlivenexttoabigcliff .• Thenanearthquakehappens,causedbyaminionfootthatcrashesdownontheearthandflattensthegrass .

• Jack&JillrealizethecliffisactuallyEvilMisterFred’scastle .• TheyenterthroughaholeinthewallandseeEvilMisterFredyellingathisminons .• Jack&JilleachclimbintooneofEvilMisterFred’searsandstartwhispering,tellinghimtobenicetotheminions .

• ThiscausesEvilMisterFredtohavenightmares,andhethinkshe’sgoingcrazy .• Finallyoneday,JackjumpsoutofEvilMisterFred’searandlandsonthetable .EvilMisterFredthinkshe’sanantandisabouttosquashhim,untilJackscreams .

• Thinkingit’satalkingant,EvilMisterFredtrapsJackunderanoverturnedglassandplanstotakehimtothecircussohecanmakelotsofmoney .

Story Recap (cont.)

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Ending:

• Jill,stillinsideEvilMisterFred’sear,tellshimhemustfindachocolate-covereddoughnut .• Shetellshimhecanfindoneoutside .• EvilMisterFredwalksoutside,leavingJackonthetableundertheglass .• Jackhadantstrength,soheliftsuptherimoftheglassandgetsout .• Herunsoutside,callstheAcmeStoreofEverything,andordersagiantfresnellens .• ThelenshoversintheskylikeaflyingsauceraboveEvilMisterFredandfocusesthesunlightonhishead .

• JackwarnsJilltogetoutofEvilMisterFred’shead,andshejumpsoutandontotheground .• EvilMisterFred’shatburstsintoflame,hishaircatchesonfire,andherunsawayscreaming .

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Transcript: Introduction Alongtimeago,peoplesailedshipswithbigsails,andtheyhadsteeringwheelsonthem,andthesteer-ingwheelscontrolledabigoldpieceofwoodthathungaroundthebacklikeafinandpointeditthiswayandthat .Theycalleditarudder .Andtheywouldsailduringthedaytimeandtheywouldsailduringthenighttime .Andalotoftime,theycrashedintothelandandtheirshipsunk--glug,glug,glug,glug .Andtheyallhadtoswimaway .Andtheysaid,“Whatwe’regoingtodois,we’regoingtosetupsomelightsontheland .”Sothere’ssomelandouthere,andsomeoceanoutthere,andshipscomingbywiththeirsailsandtheirbigcannonsandtheirflagsandstuff .Theywouldputsomelightsouthereonthelandtowarnthem,soatnighttheywouldn’tjustcrashintotheland .

Inthosedaystheydidn’thavemuchinthewayoflights .Youcouldputacandleoutthere,butassoonasthewindwouldblow,thecandlewouldgoout .Sotheyputsomeglassaroundthecandletohelpkeepthewindfromblowingitout .Theyputthecandleinaniceglassbox .Nowthewinddidn’tblowitout,sotheysaid,“Okay,thisisgreat .”Buttheguysoutatseacouldn’tseethecandle .Itwastoosmall .Theysaid,“Noprob-lem .We’llputahundredcandlesoutthere .”Sotheyputouta

hundredcandles,andevenahundredcandleswasn’tthatgood .Sotheysaid,“Forgetthat .We’llbuildabonfire .”Sotheybuiltthesebigfiresoutthere,andthewindcouldn’tblowoutthebigfires,andpeoplecouldseethemprettywell .Butifitrained--uh,oh--firewentout,shipswentcrash!Sotheyputabigglassboxaroundthebonfire .Andthenitwouldn’tgoout,andtheycouldseeitfromalongways .Butabonfirerequireslotsofwood .Andtherewereplacesouttherewheretherewasn’tenoughwood .Sotheysaid,“Weneedanefficientwaytomakethiswork .”

Inthosedays,theykilledwhales,andtheycutthewhalesalltopieces .Andtheytookthefatofthewhales,andtheyputitinagreatbigblackpot,andtheylitafireunderit,andthefatturnedintooil .Andtheyscoopedoffthebestpartoftheoil,andtheyusedthattomakecandlesandlanterns .Soifyoutookoneofthosekindsofthings,alanternlookskindoflikethis[holds up a hurricane lamp].They’dfillthebottomwithoilandthenhaveapieceofclothinside .There’sawickinthere,andthewickcangoupanddownlikethis .Andyoucantakethisoff[removes glass chimney]andyoucanlightthewick,andyoucanputthatbackon,anditwouldmakeaniceflame .Butyoustillcouldn’tseeitfromalongwaysaway,becausethelightgoesoutthisway,itgoesoutthatway,itgoesouteverywhereexceptstraightways .

AndtherewasaFrenchguy,hewasn’taphysicist,hewasn’tapersonthatstudiesmuchofanything,excepthehadthisbrilliantidea .Hesaid,“IknowhowIcanmakelightbendandgothewayIwantitto .”Be-causehe’dlookedatthingslikepiecesofglasswithcurvesonthem .Andhe’dtakeabigcurvedpieceofglasslikethat--thisisamagnifyingglass--andyouputacandleoranykindofaflamebehindit .Thelight Hurricane Lamp

Sailing ship with lights in a glass box.

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canbefocusedsothatitworksmorelikeastraightbeamrath-erthanonethatjustspreadseverywhere .Butalensthisbiginthosedayswasreallyhardtomake .Bigchunkofglass,andasitcooleditalwaysbroke .Hesaid,“Oh,man,everytimewemakeoneoftheseitjustbreaks .”Sohesaid,“Well,let’stryatrick .Let’skindofhollowitout .Let’sgostepwisehereandseeifthatworks .”Sotheyholloweditout,anditdidn’tbreak,butitdidn’tworkverywellasalenseither .Sothenhesaid,“Ratherthanhollowingoutthebackside,let’schangethefrontside .”Sohetookthiscurvyshapewithaflatbackandhesaid,“Let’sjustpretendlikeweslicedthelensupinawholebunchofpieces,likethat .Andthenwe’llcutoffthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthatpiece,andthebackofthispiece .Andthenwe’llthrowawayallthisglassandrestackthem .”AndhislastnamewasFresnel .It’spronounced“fre-NELL .”

Andthethingheinventedlookedlike--heretheyare .Thisisoneofhislenses .Ismyheadrightsideup?Yeah?Okay,we’lltryanotherone .Andanotherone .Andthesearemadethisway,wheretheycuttheweirdbackoutofitandrestackedthepieces .[Holds up another lens.]Okay,ismyheadrightsideup?Yep?HowcanImakemyheadupsidedown?[Student: Turn it around.]Okay .There .Now,ismyheadupsidedown?[Students: No. Flip it over.]Flipitover .Okay .Upsidedownhead?[Students: No.]No .HowcanImakemyheadupsidedown?[Student: If you bend it . . .]IfIbendmyhead,it’llbeupsidedown .There’sanotherwaytodoit,though .[Student: Angle it!]Okay .[Stu-dent: No. The other way.]No .There’sanotherwaytodoit .[Student: Turn it so it’s a diamond, sort of.]Diamond .HowaboutifIgolikethis[moves lens further away from his face].There’ssomebody,rightaboutthere .[Student: Gigantic.]Gigantic .Isitrightsideuporupsidedown?[Students: Right side up. Upside down.]Iwantittobeupsidedown .[Moves lens out to arm’s length.]Ineedlongerarms .[Student: It’s upside down.]Itshouldbeupsidedownnow .It’supsidedowntothepeopleintheback,butrightsideuptothepeopleinthefront .Now,thisisamagnifyingglass,right?Becauseyoucanmakethingsbigger .Infact,whatifIholditrighthere[puts lens in front of student’s face]andthenIholditrightthere[puts it in front of the face of another student who is facing the first one].AndIcouldmakeitgolikethat[places lens between pairs of students, moving it back and forth between their faces].[Puts lens directly in front of the video camera and moves it back and forth.]Makesmedizzy,Idon’tknowaboutyou .

Okay,welltodaywe’regoingtoexperimentwiththiskindoflensandwithotherkindsoflenses .Butfirstweneedtodivideupintogroupsandhavesomecrazystories .

Fresnel lens, stepwise and sliced.

Upside-down image at arm’s length.

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Story: “Jack and Jill are Ant-Size”OnceupatimeJackandJillwerelivingwithants .Andifyou’relivingwithants,grasslooksreallybig .JackandJillhadtoputthemselvesintoshrinkifyers .Well,here’sabladeofgrass .Here’ssomemoregrass .Grassreallyisn’tallthatclosetogetherwhenyougetdownlow .Anddidyouknowthatgrasshasteeth?Yep,ifyougoplaywithabladeofgrass,it’sgotteeth .Usuallyit’sontheedgeslikethat .Someofourgrasshasteethlikethis .Youjustneverknowwhereit’sgoingtohaveitsteeth .Andweneedanantdownthere .Howmanypiecesarethereinanantbody?[Students: Three!]Three?Isthereahead?Andwithsomeantennae,maybe?[Student: And an abdomen.]Okay,ishisabdomenbigorsmall?Notsobig .Andthenabodypart .Andthelegsareusu-allyattachedtotheabdomen,Ithink,likethat .There’sanant .Okay .AndJackandJillmadethemselvessmall .Sohere’sJack .Here’sJill .Andthey’reridingantsaround,doingantrodeos,playingantgames,jumpingfromoneanttoanotherastheantsareracingallovertheplace .

Fortheirsize,antsareincrediblystrong .Antscanclimbstraightupcliffs,theycanjumpfromplacetoplace,theycanpickupincrediblyheavyobjects .AndsupposeJackandJillhadahouseoverhere,andtheantsareonthemove .They’remigratingfromoneplacetoanother,andJackandJillwanttohavetheirhousemoved .Well,alltheyhavetodoistellanant,andtheantcanpickupthewholehouseandwalkawaywithitjustcarryingitinhisfrontpaws .He’sgotfourotherpawstoworkwith .Andthey’regoingup,andthenewplacewheretheymovedhap-penstohavethisreallytallcliffnexttoit .Andthecliffhasanopeninglikethat .Andtheydon’tknowwhatitis .It’ssohuge,whentheylookatit,itjustlookslikeitgoesonforeverandeverandever .Andtheywerebusyplayingoutthereinthegrass,andallofsuddentherewasanearthquake .Kaboom!Kaboom!Ka-boom!Andtheyheardthunder--Arrrrgggghhh!Totheirears,theycouldn’tunderstandwhatthiswas .Ahugeshadowcameacrosstheland .Andthensomething--theydidn’tknowwhatitwas--asomethinghugecameandcrushedawholebunchofgrassandwentaway .Itwasaminionfootprint .

AndJackandJillsaid,“Oh,no!Thatbigthing,whateveritis,mustbeEvilMisterFred’scastle .Andwe’retiny,andtheycouldsteponusandnotevenknowit .We’djustbesquishedontheground .Sowe’dbetterfindasafeplacetogoinstead .”

SoJackandJillandtheirantfriendswentinsideEvilMisterFred’scastle .Pretendlikethisisaholeinthewall .AndEvilMisterFredwasinthere,buthewasagianthugeguy .AndJacksaid,“Oh,boy,let’splaysomegamesonEvilMisterFred .”SoEvilMisterFredwassittinginhischairgivingor-derstotheminions:“Dothis!Dothat!Don’tdothis!Don’tdo

Jack & Jill Riding an Ant

Jack & Jill’s House

A Hole in the Wall of the Castle

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that!Stopthat!I’mgoingtopunishyouforthat!Intothedungeonwithyou!”Alltheseorders .AndJacksneakeduponEvilMisterFred,climbeduphischair,wentaroundtohisear,climbedinhisear,andthenhesaid,“BOO!!!”AndEvilMisterFredjumpedsohighhehithisheadontheceiling .AndJacksaid,“Yeah,Ilikethis .”AndEvilMisterFredwastryingtocleanouthisears,becausehethoughttherewassomethingwalkingaroundinhisears .AndJillsaid,“Wow!ThatJack .That’ssomuchfun .”Sosheclimbedinhisotherear .

Andthentheywerereallyquiet .Theydidn’tsayanythingatall .AndtheyfeltlikeEvilMisterFredstoppedmoving,andtheywondered,“What’shedoing?”Thentheyrealizedhewassleeping .AndJacksaid,“EvilMisterFred . . .tomorrowmorningwhenyouwakeup,youwillgivetheminionsgoodfoodtoeat .Andyou’llbenicetothemalldaylong .”AndEvilMisterFredthoughthewashavingnight-mares,andhewasrollingoverandhesaid,“No!No!No!Can’tdothat!”AndJackandJillweretryingtotrickhisbrainsohe’dbenicethenextday .

Well,thiswentonfordayafterday,andEvilMisterFredcouldn’tgetanysleep,hewasdraggingaround,hehadaheadache,hiseyeswereallredandbleary,hedidn’tknowwhatwasgoingon .ThenonedayJackgotoutofhisearandwasplayingaroundonthetablegettingsomethingtoeat .AndEvilMisterFredsawhim .Anantonhistable .Hesaid,“Don’tlikeants!”AndhegrabbedhiscuplikehewasgoingtosquashJack .Andhegoescrash!--andJackdodgedoutoftheway .Crash!AndJackdodgedtheotherway .AndJacksaid,“Stopthat!!”AndEvilMisterFredheardthislittletinyvoicesaying,“Stopthat!”Hesaid,“What?Atalkingant .Wow!Icouldmakeamilliondollarswiththecircuswithatalkingant .”

Andnowhe’stryingtocatchJack .Heturnedthecupover,andnowhe’stryingtoputitontopofJacktocatchhim .Andeventually,sureenough--Jack’strappedunderthecup .AndEvilMisterFredcarefullyslidalittlepieceofpaperundertheedgeofthecup,andnowheturneditover,andhe’sgotJackinajar .Ho,ho!Jillisstillinhisear .Jackistrappedinthejar .Andhesays,“NowI’vegotit .Ant,talktome!”AndJackwent[keeps mouth tightly closed].Hesays,“Comeon,ant,saysomething .”Rattle,rattle,rattle .AndJackwouldn’tsayathing .AndEvilMisterFredsaid,“Ifyoudon’ttalk,I’mgoingtosquishyou!”AndJacksaid,“Don’tdothat!”SoEvilMisterFredsaid,“Iknewit!Youcantalk!I’mgoingtoputyouontv .I’mgoingtoberich .”AndJacksays,“Iwon’ttalkontv .”AndEvilMisterFredtookhisfingerandheputitnearJackandhesaid,“Oh,yes,youwill .”Now,ifyouwereJack,orJill,andyouwantedtosomehowgetyourselfoutifthisterriblesituation,whatwouldyoudo?

Imagination and Brainstorming Time[Students make suggestions](THEREARENOWRONGANSWERS!Whatevertheysay,youshouldreply:“That’sagoodidea,”“Theymightdothat,”etc .Afterbrainstorming,proceedwiththeexperi-ments,thenfinishthestory .)

We’llleavethis“TobeContinued . . .”

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Experiment:

Demo:

Experiment 1: Magnifying Lenses

Andthefirstexperimentisgoingtobewithordinarymagnifyingglass-es .We’llseeifwehaveenoughsothateverybodygetsamagnifyinglens .Whenyougetamagnifyinglens,youcanofcourselookatyourfingersandstuffandseehowmuchtheymagnify .Butthen,looktoyourneighbor,andseehowyourneighborchangeswhenyoumoveyourlensescloserorfurtherfromeachother,andcloserorfurtherfromyourowneyes .You’rejustgoingtomovethembackandforth .Seeifyoucanlookintotheirbrain .Lookrightattheireyes,andseeifyoucanseeintotheirbrain .Andifyoulookintotheirbrainandfindnothingthere,thatmightexplainafewthings .Ifyoulookintotheirbrainandfindacom-puterwithawholebunchofflashinglights,thatmightalsoexplainafewthings .Whatdoyouthink?[Instructor passes out a magnifying glass to each student and they experiment with them.]

Here’samagnifyingglasswiththelittlelinesonit .[Passes out fresnel lenses, one per pair of students, and they experiment with them, alone and in combination with the magnifying glasses.]

Demo 1: Try to Burn a Fire Brick

Here’sabrickthingandapropanetorch .We’regoingtoseeifwecanburnthebrickwithapropanetorch .Thistorchburnsat1,950degrees .Youcanseethatit’smakingitorange .Isitmeltingthebrick?[Students: No. Yes.]Doyouseethebrickdripping? [Students: No.]Isitformingaholeinthebrick?[Students: No. Yes.]Canyouseetheholeinthebrick?[Stu-dents: No.]Soit’snotformingaholeinthebrick .Isitburningmyhand?[Students: No.]Okay,we’reusingthisasacompari-

son .Thisisabout2,000degrees,andit’snotmeltingthebrick,it’snotburningaholeinthebrick .Doyouthinkyoucouldburnaholeinthebrickwithyourmagnifyingglass?[Students: Yes. No.] [Student: When you put the flame behind the magnifying glass.]Oh,maybeputtheflame--what’sabiggerflamethanthis?[Student: The sun.]Ah,thesun .[Student: How about the lights?]Thelightsdon’thaveany-wherenearasmuchenergyasthesun .[Student: Let’s see the brick.]Doesn’tlookanydifferent,doesit?Butit’sreallyhot .

Trying out magnifying glasses and fresnel lenses.

Propane Torch and Fire Brick

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Experiment:Experiment 2: Burning Things with Magnifying Lenses

Now,ifyouwanttoburnsomethingwithamagnifyingglass,thesunneedstogothroughitandformalittledot .Sosupposeyou’retryingtoburnaholeinapieceofpaper .Whenyouholdyourmagnifyingglassoverit,andyouseealittledotwithatailthatlookslikethat,thistailisextrasunenergythatisn’tbeingfocusedatthedot,andyourpapermightnotburn .Ifwecanfocusitsothatyouseejustaperfectlittlerounddot,thenyourpaperwillburn .Ifyouhavethesunbehindyou,andyou’reholdingyourpaperlikethisandyourmagnifyingglasslikethat,chancesareitwon’twork .Becauseyou’llbeinyourshadow .

Ifyouhavethesuninfrontofyou,andyouholdyourpaperlikethisandyourmagnifyingglasslikethis,youmightburnaholeinyourshirt .Ifyou’resideways,withthesuntoyousidewaysandhavethepaperpointingatthesunandthemagnifyingglasspointingatthepaper,itmightwork .Whileyou’redoingit,itmakesareallybrightspot .Todayit’snottoobright,soit’sprobablynottoomuchofaproblem .Butwe’rejustgoingtotaketheglassmagnifyingglasses,nottheplasticones,outside .We’regoingtogiveyoupiecesofpaperandcupsofwater .Whydoyousupposewe’regivingyoucupsofwater?[Student: If it catches on fire.]Yeah,ifyourpapercatchesonfire,you’llhavethisfireextinguisher .You’regoingtoworkbysomeoneelse,sothere’llbeonecupofwaterforeverytwopeople .Sositbysomeoneelse .Whenyougetacup,gofillitupinoneofthosebucketsoverthere .[Instructor passes out paper and permanent markers.]I’mgoingtogiveyouapieceofpaper,andyou’regoingtodrawonapieceofpaperusingacoupleoflightcolorsandacoupleofdarkcolors .Don’tgetyourpaperwet .Somelightcolorsandsomedarkcolors .Whenyougooutside,you’regoingtoshinethemagnifyingglassonthelightcolorsandthedarkcolorsandseewhathappens .[Students color their papers.]

Whenwe’reoutside,we’llgiveyousomegoggles .Theseareyoursuper-duperblindguygoggles .Theyflipupsoyoucansee,andthentheyflipdownandyou’reblind .Thisisalwaysagoodthing .Andifyoufeelthatthedotyou’relookingatistoobright,youjustflipthemdown .Youmightbeabletoseethedot,andyoumightnot .Socomeoverhereandwe’llgiveyousomeblindguygoggles .Bringyourcupandyourpaperwithyou,andyourpartner .Afteryougetit,youcangooutintheparkinglot .[Students go outside, sit on the ground and try to burn their papers with the magnifying glass.]

Ifyou’vealreadyburnedyourpaperinabunchofplaces,gooverthereandgetadryleafandbringitback .Youcanalsotrytoburnyourcup .[Students try to burn a dry leaf or their cup.]

Okay,everybodygoandgetagreenleaffromovertherebythefenceandbringitback .[Students try to burn a green leaf.]

Burning Paper with Sunlight

The focused dot should look like the one on the left, not the one on the right.

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Demo:

Okay,time’sup .Putyourleavesandyourpiecesofpaperinthebluegarbagecanhere .Setthemagnify-ingglassessoyoudon’tdroptheminthemagnifyingglassbox .Keepyourgoggles .

Demo 2: Burning Things with Giant Fresnel Lenses

[Keep giant lenses covered with towels until ready to use.]You’regoingtohavetobewhereyoucanseewhat’sgoingon,ontheselittlebricks .Butyoucannotbebehindthem,youhavetobeinfrontofthem .

Thesearejustbiggermagnifyingglasses .Wehaveamedium-sizeoneandalargerone .Seehere,thedotishuge .Seethislit-uparea?Weneedtomakethedotsmaller .Putyourgogglesonifyou’regoingtowatchthedot .Firstwe’lltiltitup .There,nowourbrickisgettingtoasted .We’regoingtosetthisoneupaswell .

Herewehaveapieceofwood .Canyouseethiswoodthroughyourgoggles?[Students: No.]Youcanflipthemuptolookatthewood .Justflipupyourgogglesandyoucanseewhat

we’regoingtoburn .Firstthingisapieceofwood,okay?Thenyoucanflipyourgogglesbackdown .Andcanyouseethebrightspotfromwhereyouare?Okay,we’llputthewoodwherethebrightspotis,rightthere .Seehowbigthedotis?It’skindofbig,but . . .Doyouseeanyflameswithyourgoggles?[Students: Yes. No.]Okay,youcanflipyourgogglesupandlookatituphereandseethatitburnedthisside .Doyouseethatitalsowentallthewaythroughthewood?Yeah,thisdarkspotiswhereitburnedthrough .We’lljustputitintherealittlebitlonger .Flames .Andnowyoucanseetheothersideisallblack,burnedallthewaythroughthechunkofwood .

We’lltryitwiththisguy[puts a piece of wood on the second furnace].Thisoneneedstobemodified .Focuspointisrightthere .Canyouseethatfromwhereyouare?Okay,we’lltakeitout .It’sjuststartingtogetbrownontheotherside .Flames?Thisoneisn’tquiteashotastheotheroneistoday .Thisoneisjuststartingtocomethroughnow .SeetheXmarkonit?There’ssomedirtonthelensorsomething .

Soifyouwanttolightwoodonfire,that’sagoodwaytoburnwood .Youcanflipupyourgoggles .Nowlet’stry . . .we’llpoursomewateronourwoodsoitwon’tbesohot .Thatlooksgood .

Let’stryamarshmallow .Doesthatlooklikeamarshmallow?It’sastalemarshmallow .Ifyoulookatthisbrickwithyourgoggles,thelighthasmeltedaholeinourbrick .Rememberweputthe2,000de-

Giant Fresnel Lens in a Tiltable Frame

Burning Wood with Sunlight

greetorchonit,anditdidnothingtothebrick?Thesunjustmeltedacaveinourbrick .There’sthatmarshmallow .Now,themarshmallow,isitallburnedandexploded,orisitjust--[Student: On the other side.]Theothersidewasnearthebrick .Thesidethesunwasshiningonisn’tburnt,isit?Themarshmallow’ssowhite,itreflectsmostofthesunlight .Thesidefacingthebrickisallburnedbecausethebrickwassohot,itgaveoffaredlightandtoastedthemarshmallowinthebackside .Let’sstickitbackinthesunlight .Thereitgoes .We’llleaveitlongerthistime .[Marshmallow starts to flame.]Oh,poormarshmallow .Blackenedmarshmallow .Let’stryitwiththisguy[moves marshmallow to second furnace].We’lljustsetitrightthere .Thereyougo,littlemarshmallow .Haveagoodtime .Burn,marshmallow .It’sgrowing .It’sgettingbigger .Ourmarshmallowisturningintopurecarbon .Yummy .Shallwetakeitoffandseewhatitlookslike?Nowwehaveablackmarshmallow .[Places marshmallow in cup of water.]

Let’stryasponge .Shallwegetitwetfirst?Yeah,let’smakeitwet .Here’sawetsponge .Putthegogglesdown .Lookhowlongitlasts .[Student: Look at the water coming out.]Yep,it’smakingsteam .Sizzle .Evaporating .Ifyouwanttoprotectyourselffromsuper-hotsun,youshouldcoveryourselfwithsponges .Lookatthat .Allthattimeinthere,andthespongeishardlydamagedatall .It’sprobablykindofhot .Let’sputitwhereourmarshmallowwassittingandleaveitthereforawhile .We’llcookoursponge .

Let’sputapennyonthisone .There .Thebrickissmoking .Weputapennysittingwherethebrickis .What’sthepennydoing,canyouseeit?Ourpoorpennyisturningintosmoke .Thatpennyisanewpenny .It’smadeoutofzincandcopper .I’mgoingtofindapennythat’sanoldpennythat’smadeoutofpurecopper,andwe’llthrowthatinthere .Okay,nowwe’regoingtoputonthecopperpenny .Thisone’spurecopper,itshouldhavenozincinit .Therehegoes .ThisisAbeLincoln .There’sAbe .Oh,Abe’sfacejustmelted .PoorAbe .NowAbehasturnedintoadrip .Oh,man .Abehasmeltedcompletelyaway .Aww,bye-bye,Abe .

Now,we’regoingtoputourlavarockontopofwhereAbewassitting .Andlet’sseeifwehaveenoughheattomeltit .Ohyeah,it’smelting .It’sturningintolava .Therockisbubbling .I’mgoingtomeltalittlebitdeeperholeinit .Thelavaisstartingtoflow .It’sdripping .Thinkofthepeopledownbelowthevolcano .Thepotatochipsintheircupboardarenowgoingphoom!Okay,it’smelted .Don’ttouchitthistime .Nowyoucanseethedifference .Therockhasturnedadarkercolor,andit’sallmelted .Okay,there’sourmeltedrock .

Rock-it Science Teacher’s Guide Solar Furnaces -- Page 14

The White Marshmallow reflects the sunlight, so it doesn’t burn right away.

Steam Rises from the Wet Sponge

Lava Rock Melted in the Center.

Rock-it Science Teacher’s Guide Solar Furnaces -- Page 15

End of Story * DO NOT * present this part of the lesson until after the experiments!

End of Lesson

If y0u have questions about this lesson, please ask them through the online Teacher Support Forum on our web site.

Sowemeltedmarshmallows,weburnedwood,meltedpennies,weburnedasponge .Ithinkthespongeisdead--weburnedthesponge .Itsmellsreallybad .[Student: Burn the cup of water.]Oh,hewantstoburnacupofwater?[Holds cup of water over fire brick.]Thebrickismeltingit .Thelightusuallygoesrightthroughwater,itjustsitsthere .NowIthinkwebettergobackinsideandfinishourstory .

SoJackisinsideEvilMisterFred’sear,Jillisstilloutsidesomewhere .[Student: Jack is outside.]Oh,didJackgetoutside?That’sright,Jackisunderacup .Let’sputJackunderacup .There .There’sJackunderthecup .AndJillisoutsidesome-where .[Student: No, she’s inside.]Oh,isshestillinsideEvilMisterFred’sotherear?Oh,good .That’llmakeiteasierforus .SoJillisinhisotherearandshecantalktohim .

Andshesays,“Hello!I’mJack,I’minsidethecup .Youcanhearmenow .I’minsideyourbrain,too .Antscancommunicatewitheachother .Theyhavethisconnection,andnowJackinsidethecupcantellyourbrainwhattodo .”AndEvilMisterFredsaid,“No,hecan’t .Nobodycantellmewhattodo .”AndJillsaid,“Yes,hecan .Youhaveadeepdesireforachocolate-covereddoughnut .Think . . .chocolate . . .doughnut .”AndEvilMisterFredsaid,“Ooooohhh!Dough . . .nut!”Andhestartedlookingalloverthecastleforadoughnut .

AndJackisunderthecup .Well,antshaveincrediblestrength,andsodoesJackwhenhe’ssmall .Hegottotheedgeofthecup,andhelifteditupandgotoutfromunderitwhileEvilMisterFredwassearch-ingforadoughnut .Andhesaid,“Jill,tellhimtogooutside .”AndJillsaid,“There’schocolate-covereddoughnutsoutside!”AndEvilMisterFredranoutsideandJackgrabbedontohisshoeashewalkedby .AndnowJackandJillareoutsidewithEvilMisterFred .

AndJacksaid,“Hangon .”AndhecalledtheAcmeStoreifEverythingandorderedagiantmagnifyingglassupintheair .Whatshouldwecallit?Aflyingsaucermagnifyingglass .Hesaid,“Jill,runforyourlife!”SoJillranoutofhisear,jumpedontohisshoulder,downhisarm,andoffintothegrass .AndJackranintothegrass,too .Andthegiantmagnify-ingglasswashoveringupintheskylikeabigjellyfish .AndEvilMisterFredisstillsearchingforachocolate-covereddoughnut .Andthemag-nifyingglassfocusedonEvilMisterFred’shat,andhecouldn’tfigureoutwhatwasgoingon .Hefelthotallofasudden .Andthenhishatwentpfffft!intoflames,andhishaircaughtonfire,andheranawayscreaming,“Ahhhhhhhh!”Andeverybodylivedhappilyeverafter,exceptEvilMisterFred .

Jack under Cup

Flying Saucer Lens