Composite Functions

8
CSinAlgebra|Lesson8
CompositeFunctions
Lessontime:30-60Minutes
LESSONOVERVIEW
Inthepastlessonsstudentshavedefinedvariableswhichwillallowthemtoeasilywriteexpressionsthatreferto
thesamevaluerepeatedly.Inthisstage,theywillwritesimplefunctionsthat,likevariables,allowstudentsto
abstractoutrepetitiouselementsoftheirprograms.
LESSONOBJECTIVES
Studentswill:
Analyzeanduseexistingfunctions.
Modifyexistingfunctions.
Createnewfunctions.
Createsimilarshapesbychangingsizeparametersonfunctions.
ANCHORSTANDARD
CommonCoreMathStandards
8.F.1:Understandthatafunctionisarulethatassignstoeachinputexactlyoneoutput.Thegraphofafunction
isthesetoforderedpairsconsistingofaninputandthecorrespondingoutput.1
Additionalstandardsalignmentcanbefoundattheendofthislesson
TEACHINGSUMMARY
GettingStarted
1)Vocabulary
2)Introduction
Activity:CompositeFunctions
2)OnlinePuzzles
TEACHINGGUIDE
GETTINGSTARTED
1)Vocabulary
Thislessonhasonenewandimportantword:
Parameter-Avalueorexpressionbelongingtothedomain.
2)Introduction
Definingareusablevalueishelpfulwhenaprogramhaslotsofidenticalexpressions.Sometimes,however,a
programhasexpressionsthataren’tidentical,butarejustverysimilar.Aprogramthathasfiftysolid,green
trianglescanbesimplifiedbydefiningasinglevalue,aslongastheyareallthesamesize.Butwhatifaprogram
hasfiftysolid,greentrianglesofdifferentsizes?
ThinkabouttheImagefunctionsyouhavealreadyused,likestarandcircle.Theytakeinputsandproduce
images.Similarly,wemightwantagreen-trianglefunctionthattakesthesizeasaninputandproducesagreen
triangle.Theprogramminglanguagedoesn’tprovidethisfunction,butitdoesletyoudefineyourownfunctions.
Wewanttodefineourownfunction(let’scallitgt,forgreentriangle)thattakesinaNumberasthesizeparameter
andproducesasolidgreentriangleofwhateversizewewant.Forexample:
andsoon...
ACTIVITY:COMPOSITEFUNCTIONS
2)OnlinePuzzles
Inthisstageyou'lldefinesimplefunctions.HeadtoCSinAlgebrastage8inCodeStudiotogetstarted
programming.
Derivedfrom