Topic3.2Area
Strand3:Measurement Measuring
Knowledgeandpractices
Element: Strand3:Measurement
Measuring
Knowledge Practices
Approximatingtheareasof irregular shapescoveredwithsquares,halfsquares, andpartialsquares
Theareasof rectangles(includingsquares) canbecalculated bymultiplicationofside lengths.
Calculatingtheareasofrectangles (including squares)usingmultiplicationof sidelengths
Overtoyou!
• CompletetheGet readyquizonlineor onpaper
Areyouready?
Clicktoopen
• Topic 3.2Getreadyquiz
Beforewestart, let’ssealifyou’re readytogo!
Today,wearelearning to 1
• Understandwhatareais
Success
criteria
forthislesson
Ican:
• explainthat areaistheamountofspaceinsideashape
• countwholesquaresinsideashape
• recordthetotalareausing squareunits
• Approximatingtheareasofirregular shapescoveredwith squares,halfsquares, and partialsquares
• Calculating theareasofrectangles(including squares)using multiplication of sidelengths
• Whatis area?
Area istheamountof spacea flatshapecovers.
Perimeter=Lengtharoundthe outside ofa shape
Area=How manysquaresfitinsideashape.
Thisisa squarecentimetre.
Eachsideofthesquaremeasures1cm. Wewritethisas1cm².
Howmany1cmsquarescan fitinsidethisrectangle?
Wesaythisrectanglehasanareaof8 cm².
Now
youcalculatetheareasoftheseshapes...
Overtoyou!
• Inpairs,lookatthe Investigating areasheet.
• Estimatethearea oftherectangle.Howmany1cmx1cmsquaresdoyouthink wouldfitinside therectangle?
• Usingyourruler–drawthe1 cmx1 cmsquares ontoyourrectangle.
Hint: Draw dots 1 cm apart along the side lengths as shown, then draw the lines across
• Countthesquarestoworkouttheareaoftherectangle.
• Discuss
Clicktoopen
• BLMX.XInvestigating area
Blacklinemaster
Lookingahead
Howdoyouworkouttheareaofashapewhenitdoesn’tfit neatlyintothesquares?
Stand ifyou thinkit’s true.
True
orfalse?
Sit ifyou thinkit’s false.
Thisrectanglehasanareaof8cm²
EndofLesson 1
Lookingback
Wecanfindtheareaof ashape,bycountinghowmany 1cm x1cmsquaresmakeup theshape!
Today,wearelearning to
• Choosethebestunitfor measuring area
• Approximatethearea ofirregularshapes
Successcriteriaforthislesson
Ican:
• countwholesquaresinsideashape
• combinehalfsquarestomakewhole squares
• makesensibleestimatesforpartial squares
• recordthetotalareausingsquareunits(e.g.cm²,m²)
• Approximatingtheareasofirregular shapescoveredwith squares,halfsquares, and partialsquares
NZC
Howwouldwemeasuretheareaofthistrampolinemat?
Tomeasurethe area ofthemat,youwouldneedahugenumberof 1cm x1cmsquares. Is there a better way?
• Someareasare verylarge,anditwouldn’tmakesense tomeasurethemin squarecentimetres.
• Inthesecases,wecouldmeasureinsquaremetres.
• Wewritethisas1m².
Overtoyou!
Which
unitwouldyouusetomeasurethese?
cm² or m²
Apaddock
Apictureframe
Overtoyou!
Asyoucansee,notallshapeswillfitneatly intogrid squares.
Trythis! Ido
Notallshapesfitneatly intothesquares.
10 fullsquares 5halfsquares
Area =12.5cm2
Howcouldweworkouttheareaofthese shapes?
Fullandhalfsquares
Whatisthearea(incm2)ofeachshape?
15 fullsquares
3half squares
Area =16.5cm2
12 fullsquares
6half squares
Area =15cm2
Howcouldweworkouttheareaofthisshape?
Itisa bittrickier!Ithassomepartialsquares.
7fullsquares 4.5partialsquares Area =11.5cm2
Partialsquares: = half
Workouttheareaoftheseshapes
10 fullsquares
10 halfsquares
Area =15cm2
9fullsquares
4half squares
3more(madeofpartialsquares)
Area =14cm2
OpenyourStudentWorkbookand completethisactivity:
Gotopage
Connectandreflect Think Pair Share
Whatdoesthewordapproximatemean?
EndofLesson 2
Lookingback
• Wecanfindtheareaof ashape,by counting how many 1cmx 1cmsquaresmakeup theshape – includingwhattodowhentherearehalf orpartialsquares.
15 fullsquares 3half squares Area =16.5cm2
Estimate • a smart guess based on information
Approximate
• when it's hard to get an exact answer – an approximate is an answer as close as possible to the answer
Area
• the amount of space inside a flat, 2D shape
Today,wearelearning to
• Findthearea ofa rectangleusing multiplication
Success
criteria
forthislesson
Ican:
• findthelengthandwidthofa rectangle
• Multiplylengthxwidthtofindarea
• usesquareunitsinmyanswer(e.g.cm²,m²).
• checkthattheanswermakessense.
• Calculating theareasofrectangles(including squares)using multiplication of sidelengths
Usingmultiplicationtofindareaofarectangle
Thereare3rows.Thereare5squaresineachrow.
So,insteadofcountingeachsquare, wecanmultiply5x3 togetatotalof15squares.
Area ofthisrectangleis15cm².
Areaofarectangle=LengthxWidth
Let'scalculate theareaofthisrectangles.
Areaofarectangle=LengthxWidth
6cmx2cm=12cm2
Calculatetheareaoftheserectangles.
Canyoufindwidth ifgivenlength andarea?
Area =24m2 6m 3cm 10cm 8m 4m A=lxw =4x8 =32m2 A=lxw =10x3 =30cm2
Classroomrectangles
1. Yourtaskistofind3rectanglesinourclassroom, andcalculatetheirarea(e.g.the whiteboard, windowframe,classmat,bookshelf,dooror cupboard)
2. Roundyourmeasurementstothenearestmetre (e.g.3mx2m,not2.8m x1.6m).
3. Record yourmeasurementsonthesheet provided.Calculatethearea ofyour3chosen rectangles(includeunits!)
4. Answerthebonusquestionatthebottomof the tasksheet Clicktoopen
• BLMX.XClassroom rectangles
OpenyourStudentWorkbookand completethisactivity:
Gotopage
Thumbscheck
Icandothis! I’mgetting there! Ineedhelp!
Howconfidentareyouusing multiplicationofsidelengthstofindthearea ofa rectangle?
EndofLesson 3
Lesson4overview
Approximatingarea (half andpartialsquares)
Findingtheareaofa rectangleusingmultiplication
Findingthearea ofcompoundshapes
Lookingback
Areaofarectangle=LengthxWidth
6cmx2cm=12cm2
Today,wearelearning to
• Findthearea ofcompoundshapesmadeupoftworectanges
Successcriteriaforthislesson
Ican:
• splitacompoundshapeintotworectangles.
• findtheareaofeachrectangle.
• addthetwoareastogether.
• Calculating theareasofrectangles(including squares)using multiplication of sidelengths
NZC
Howcouldweuseournew
knowledge
Areaofrectangle=LengthxWidth toworkouttheareaofthisshape?
Calculatingarea
Area ofRectangleA
Area =10x5 =50cm²
Area ofRectangleB
Area =7x4 =28cm²
Totalareaofshape
Area =50+28=78cm²
Wecanbreakitupintwoways:
Word problem
Aschoolprincipalwantstoreplacethecarpetina classroomandneedstoknowtheareaofthefloor.
• Itisarectangularclassroom,measuring15mx5m.
• Theclassroomalsohasasmallrectangularspace offthesidemeasuring3mx2m.
• Pleasecalculatethetotalareatocarpet.
Firststepistoalways drawadiagram tohelpyouvisualise,andtorecordthe sidelengthandwidth measurements.
Trythis! Youdo
• Findthearea oftheclassroomintheword problem
• Usewhiteboard oryourmathsbook torecordyour calculations
AreaofRectangleA
Area =15x5 =75m²
AreaofRectangleB
Area=2x3 =6m²
Totalareaofclassroom
Area=75+6=81m²
OpenyourStudentWorkbookand completethisactivity:
Gotopage
Connectandreflect Think Pair Share
Canyoucalculatetheareaofthisshape?
EndofLesson 4
Overtoyou!
• CompletetheReview quizonlineor onpaper.
Today,wearegoingto 5
Revise Enrich or
yourunderstandingfromthis week!
• Challengeyourselfwiththe Richtaskforthistopic!
Overtoyou!
• Completethe
• Topic 3.2Richtask:Creatinggraphs
