developing calculaon and problem solving skills · 2015-11-25 · background • some of you...
TRANSCRIPT
Developingcalcula.onandproblemsolvingskills
MarianSmallNovember,2015
Background
• SomeofyouexpressedaninterestintalkingaboutdevelopingbeAercalcula.onskills.
• SomeofyoutalkedaboutdevelopingbeAerproblemsolvingskills.
• Todayisamix.• Wewillalsoblendintheac.vi.esyoutriedandarerepor.ngon.
Let’sstartwith…
• Someexamplesofopenques.onsyouusedthatwentwell.
• Talktothepeopleatyourtable.• Thetablewillchoosetwotopresenttoeveryone.
Calcula7onskills
• Myfocuswillbeondevelopingtheimportantideasthatunderliecalcula.ons,ratherthanthemechanics.Iwillalwaysbereferringtomeaning.
• Butwewilllookatvarie.esofstrategiesforperformingcalcula.on.
Facts(SmallNumbers)
• Yourcurriculumspeaksclearlytotheimportanceofdevelopingfluencywithsmallfacts.
• TheseareESSENTIALfores.ma.on,workwithpropor.onalthinking,workwithfrac.ons,etc.etc.
BUT
• Weneedflexibilitywhichcomeswithunderstandingandnotjustinstantaneousresponses.
• InyourMinistrydocuments,thereismen.onmadeofstrategieslikeMaking10,Usingdoubles,AddingtoSubtract,etc.
Addi7on/subtrac7onissues
• Everysubtrac.oncanbesolvedusingaddi.on.
• Howwouldyousolve13–8thisway?
Addi7on/subtrac7onissues
• Orderdoesn’tmaAer.
Addi7on/subtrac7onissues
• Youcanaddorsubtractinparts.• Youcan“juggle”whenyouadd.
Addi7on/subtrac7onissues
• Youcanuseaconstantdifferencewhenyousubtract.
• Addingorsubtrac.ng0isespeciallyeasy.• Addingorsubtrac.ng1ispreAyeasy.
Sohowwouldyouencourage
• 8+3• 6+7• 9–4• 12–9
ButIwouldalsoask
• Showme6sothat:• Therearemorethan2parts.• Thereare2parts-oneliAleandonebig.• Thereare2parts-similarinsize.
• Repeatabovewith25.
ButIwouldalsoask
• Showme10andshowme12sothat:• Eachisshownintwoparts.• Onepartfor10isthesamesizeasonepartfor12.
ButIwouldalsoask
• Whatnumberscouldyoudecomposeintoanumberandtwiceasmuch?
• Whatnumberscouldyoudecomposeintothreenext-to-each-othernumbers?
ButIwouldalsoask
• Predicthowmuchmore8+3isthan6+2withoutgeengtheanswers.
Addi7onandsubtrac7onprocedures
• Howwouldyouusebasetenblocksfor:• 35+48• 76+99• 81–17• 241–167
Mul7plica7onanddivisionconcepts
• Everydivisioncanbesolvedbymul.plying
• Howwouldyouusemul.plyingtosolve36÷4?
• Tosolve546÷6?
Mul7plica7onanddivisionconcepts
• Orderdoesn’tmaAer
Mul7plica7onanddivisionconcepts
• Youcanmul.plyinparts(distribu.veandassocia.ve).
Mul7plica7onanddivisionconcepts
• Youcan“juggle”factors(e.g.half/double)• Youcandouble/triplebothdivisoranddividend.
Mul7plica7onanddivisionconcepts
• Youcandivideinparts• It’seasytodivide0.• It’seasytodivideby1.
ButIwouldalsoask
• Buildarectangularprismthatis2x2x3cubes.
• Howdoesthishelpyouseethat4x3=2x6?
ButIwouldalsoask
• Makeabigarrayofcounters.• CanyoualwaysbreakitupintoliAlearrays?
Models
• Howwouldyouusebasetenblockstomodel• 8x49?• 21x21?• 512÷4• 312÷4
Whataboutintegers?
• Howdoyoumodel5–(–3)?• 5x(–3)?• (–15)÷(–3)?
Whataboutfrac7ons?
• Howdoyoumodel• 2/3+1/5• 2/3–1/5• 2/3x1/5• 2/3÷1/5
2/3+1/5
2/3+1/5
2/3+1/5
2/3–1/5
2/3–1/5
2/3–1/5
2/3x1/5
2/3x1/5
2/3÷1/5
Now
• Let’stalkaboutexamplesofques.onsyouusedtopushthinking.
• Shareatyourtable.• Yourtablewillchoosetwotopresenttoeveryone.
Nowforproblemsolving
Characteris7csofgoodproblems
• Thereissomeelementofdecisionmaking.• Thereissomereasoning.• Communica.ngaboutprocesswillworkformoststudents.
• It’sniceifyoucandrawavisual.
Characteris7csofgoodproblems
• It’sniceifthereismorethanoneapproachorevenmorethanoneanswer.
• It’sniceifyoucaneasilyextend.
Forexample…
• KaylahadjustafewmorepencilsthanLevi.• Togethertheyhad20pencils.• Howmanydoyouthinkeachonehad?
So…
• Decisionmaking?• Reasoning?• Communica.ng?• Whatsortofvisual?• Morethanoneapproach?• Extendable?
Forexample
• Wemightask:Amyis4.Sindyis6yearsolder.HowoldisSindy?
OR• WemightaskwhetherSindycanbeboth6yearsolderthanAmyandalsotwiceasold.
Possiblevisual
So…
• Decisionmaking?• Reasoning?• Communica.ng?• Whatsortofvisual?• Morethanoneapproach?• Extendable?
Or…
• Whatnumberscanyoumakebyusingonly2s,5s,+sand–s?
• e.g.3=5–2• 10=5+5• 9=5+2+2• Arethereanycoun.ngnumbersyoucannotmake?
So…
• Decisionmaking?• Reasoning?• Communica.ng?• Whatsortofvisual?• Morethanoneapproach?• Extendable?
Maybe
• Es.matethenumberofsquarecen.metresofpizzathatallofthekidsinWinnipegeatinoneweek.
So…
• Decisionmaking?• Reasoning?• Communica.ng?• Whatsortofvisual?• Morethanoneapproach?• Extendable?
Maybe
• Onerectanglehashalftheareaofanother.• Wouldtheperimeteralsobehalf?• Isitever?Usually?Omen?
Maybe
• Createrectangleswherethenumberofcen.metresintheperimeterisveryclosetothenumberofcm2inthearea.
Maybe
• Yourepresentanumberwithbasetenblocks.
• Youusethreemorerodsthanflats.• Youusetwofeweronesthanrods.• Whatcouldyournumberbe?
Maybe
• UsepaAernblocks.• Createadesignthatis1/5blueand1/2green.
Maybe
Maybe
• AngelaandBenbothhavecoins.• Benhas2½.mesasmanycoins,butAngela’samountisworth8.mesasmuch.
• Whatcoinsdoeachhave?
Maybe
• Elizabethcanrun200min2[].[]seconds.Youcanchoosethenumbersintheblanks.
• Howlongwouldittakeher,atthatrate,torun1000m?
Maybe
• AgrowingnumberpaAernincludesthenumbers25and40somewhereinthepaAern.
• HowlongwillittakeyourpaAerntoreach1000?
Meanandmedian
• Themeanofasetof10numbersisdoublethemedian.
• Whatmightthenumbersbe?
Visual
__________44____________Ifthemeanif8,thenthesumofthemissingnumbers=72
Represen7ngintegers
• Youusesome+1.lesandfour.mesasmany–1.les.
• Whatintegerscanyourepresent?Whichcan’tyou?
Visual
Horseproblem
• Amanbuysahorsefor$50.• Hedecideshewantstosellhishorselaterandgets$60.
• Hethendecidestobuyitbackagainandpaid$70.
• However,hecouldnolongerkeepitandhesolditfor$80.
• Isheahead,behind,oreven?
Times
• Howmany.mesina12hourperioddoesthesumofthedigitsonadigitalclockequal6?Trytothinkofawaytosolvethiswithoutgoingthrougheverysingle.me.Describewhatyoudid.
Legs
• Alexbuildsstoolsandtables.• Heused72legs.• Hebuilt3morestoolsthantables.• Howmanyofeach?
Somevideoproblems
• hAp://threeacts.mrmeyer.com/sugarpackets/
• hAp://mrmeyer.com/threeacts/cokevsprite/
Mathalicious
• Anothersource• Whatdoyouthink?
Wealwaysstartwithcurriculum
• Let’slookatsomeoutcomesandseeifwecandevelopsomegoodproblems.
Gr1outcome
•..compareandordersetscontainingupto20elementstosolveproblems….
Problem
• Youpar..onanumberintothreeparts.• Onepartissmall.• Onepartisabouttwiceasmuchasanotherpart.
• Whatnumbercoulditbeandhowisitpar..oned?
Possibili7es
• 15as1,2and12• 13as1,4and8• 18as3,5,and10
Let’sconsolidate
• Whatdowewanttobringout?• Thatsmallisrela.ve• Thattwiceasmuchisanumberaddedtoitself
• Thatthesmallonecouldbethetwiceornot• Thatthe3rdnumbercouldbetwicethesmalloneortwicethe2ndnumber.
• HowtoaAacktheproblem
Grade2outcome
• Demonstrateanunderstandingofaddi.onandthecorrespondingsubtrac.onby…
• Crea.ngandsolvingproblemsthatinvolveaddi.onandsubtrac.on
Firsttrythis
• Chooseanumber.• Add20.• Subtract4.• Subtractthenumberyoustartedwith.• Subtract8.• Subtract3.
Whatshouldtheyno7ce?
• Totalamountofsubtrac.onvsaddi.on• Howsubtrac.ngtheoriginalnumbermadeitirrelevant
Anotheridea
• Makeupatrickinvolvingatleast5stepssothatamerfollowingyoursteps,theresultisalways10.
Agrade3outcome
• Demonstrateanunderstandingofmul.plica.onto5x5by…
• Crea.ngandsolvingproblemsincontextthatinvolvemul.plica.on
Maybe
• Inoneclassroom,therewas1morebookinthelibrarythaninanother.
• Eachshelfineachlibraryheldthesamenumberofbooks.
• Howmanyshelvesandhowmanybooksmighthavebeenineachclassroomlibrary?
Agrade4outcome
• Demonstrateanunderstandingofareaofregularandirregular2-Dshapesby..
construc.ngdifferentrectanglesforagivenareainordertodemonstratethatmanyrectanglesmayhavethesamearea
Maybe
• Tworectangleshadanareaof20cm2butonewastwiceaslongastheother.
• Howisthatpossible?
Agrade5outcome
• Demonstrateanunderstandingoffrac.onsbyusingconcreteandpictorialrepresenta.onsto
• Comparefrac.onswithlikeandunlikedenominators.
Maybe
• 5/[]isalotmorethan12/[].• Whatnumberscouldgointheblanks?
Agrade6outcome
• Demonstrateanunderstandingofpercentconcretely,pictoriallyandsymbolically.
Maybe
• Chooseanumberthanisabout25%ofonenumberbutabout75%ofadifferentnumber.
• Whatisyournumber?• Whatarethenumbersitis25%and75%of?• Showthatyou’reright.
Agrade7outcome
• Demonstrateanunderstandingofaddingandsubtrac.ngposi.vefrac.onsandmixednumbers,withlikeandunlikedenominators,concretely,pictoriallyandsymbolically
Maybe
• Youaddtwofrac.onswithdifferentdenominators.
• Thedenominatorofthesumwas5morethanthenumerator.
• Whatfrac.onsmightyouhaveadded?
Agrade8outcome
• solveproblemsthatinvolverates,ra.os,andpropor.onalreasoning.
Maybe
• Aboxofcookiescosts1½.mesasmuchasapackageofmuffins.
• Youboughtsomecookiesandsomemuffinsandpaid$43.
• Howmanyofeachmightyouhaveboughtandatwhatprice?
Doyouwanttotry?
• Createaproblemthatmeetsanoutcomeofyourchoice.
Now
• Shareatyourtablethelessonyoureorganizedtofocusmoreonbigideasthanskills.
• Yourtablewillchoose1or2lessonstosharewitheveryone.
Fornext7me
• Let’sgoatitagain,butwithaslightlydifferentslant.
• 1)Useanopen-endedproblemthatyouthinkisvaluableforyourstudents.
• 2)Teachonecomputa.onlessonbasedonideas,butwhichprac.sesskills.
Download
• www.onetwoinfinity.caLouisRiel2