which fractions have a difference of 1/2?wms.lethsd.ab.ca/documents/general/ch2webreduced2.pdf ·...

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At the completion of this unit, you will be able to: multiply and divide fractions by whole numbers, other fractions, and mixed numbers using models, drawings and symbols estimate products and quotients of whole numbers, fractions and mixed numbers solve and create problems using fraction operations calculate the value of expressions involving fractions, using the proper order of operations communicate clearly about fraction operations Unit 6: Fraction Operations What fraction of each glass is full? Assume that the fullest glass is equal to 1. How do the fractions compare to each other? Which fractions with a denominator of 8 can be renamed in lower terms? Which fractions can be added to give a sum of 1? Which fractions have a difference of 1/2?

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  • Atthecompletionofthisunit,youwillbeableto:

    multiplyanddividefractionsbywholenumbers,otherfractions,andmixednumbersusingmodels,drawingsandsymbols

    estimateproductsandquotientsofwholenumbers,fractionsandmixednumbers

    solveandcreateproblemsusingfractionoperations

    calculatethevalueofexpressionsinvolvingfractions,usingtheproperorderofoperations

    communicateclearlyaboutfractionoperations

    Unit6:FractionOperations

    Whatfractionofeachglassisfull?Assumethatthefullestglassisequalto1.

    Howdothefractionscomparetoeachother?

    Whichfractionswithadenominatorof8canberenamedinlowerterms?

    Whichfractionscanbeaddedtogiveasumof1?

    Whichfractionshaveadifferenceof1/2?

  • Theequation2+2/3=22/3tellsthesumoftheareasoftwoofthecolours.Whichcolours?Howdoyouknow?

    redandblue4reds(1/2each)=22blues(1/3each)=2/3

    Ifayellowhexagonhasanareaof1unit,whatistheareaofeachblock?

    a)aredblock 1/2unit

    b)ablueblock 1/3unit

    c)agreenblock 1/6unit

    Whatfractionscanyouusetodescribethepatternblockdesign?

    a)1+4/2(2)=3

    b)2/33/6=1/6

    c)37/6(11/6)=15/6

    d)4/23/6=23/6=13/6or11/2

    Writeequationswithfractionsand/ormixednumberstodescribethefollowingareas.Makesureyousolveyourequations.Showyourwork.

    a)theyellowandredpartsb)howmuchmoreisbluethangreenc)howmuchmoreisyellowandredthangreenandblued)howmuchmoreisredthangreen

  • Createyourowndesignusingthefollowing:

    1.yellow,red,blue,andgreenpatternblocks

    2.atotalofeightblocks

    3.atleast2yellowblocks

    4.atleastoneblockofeachothercolour

    5.writefractionsand/ormixednumberstodescribeeacharea.Showyourwork.

    6.Gototwootherdesignsandwrite3fractionequations(addingorsubtracting)forthosedesigns.

  • Aim: I can use repeated addition to multiply fractions by whole numbers

    Multiplying a Whole Number by a Fraction

    What does the fraction 3/4 mean?

    How could you use a rectangle to model 3/4?

    How could you use fraction strips to model 3/4?

    How could you model 3/4 on a number line?

    How could you model 3/4 using a grid and counters?

    the number of parts being named

    the number of equal parts into which the whole is divided

    Fraction review:What is a denominator?

    What is a numerator?

  • Think about it

    Jana is having a party. After a few hours, she notices that 6 pitchers are each only 3/8 full. She decides to combine the leftovers to use few pitchers.

    How many pitchers will the leftover lemonade fill completely?

    Use a model to represent 8/8 of a pitcher.

    Use this model to represent lemonade from the 6 partially full pitchers. Write as both an improper fraction and a mixed number.

    When you add the above fractions, you will end up with 18/8 or 2 2/8 or 2 1/4.

    Why could you write

    3/8+ 3/8 + 3/8 + 3/8 +3/8 + 3/8 or 6 x 3/8 to describe the total amount of lemonade in the pitchers?

  • Draw 4 grids that are 6 by 2 in your notebook and show how you can represent 4 sets of 5/6.

    How could you calculate 4 x 5/6 using grids and counters?Represent the answer as an improper fraction and as a mixed number.

    4 x 5 = 4 x 5 = 20 6 6 6

    or 3 2/6 or 3 1/3

    You can also move the chips from the last grid in to fill the other three grids. This will show you your mixed number.

    4 x 5/6 is four sets of 5/6

  • 3 x 2 = 3 x 2 = 6 3 3 3

    = 2

    How can you calculate 3 x 2/3 using fraction strips? Write the product as an improper fraction and as a whole or mixed number.

    5 x 3 = 5 x 3 = 15 = 7 1/2 2 2 2

    How could you calculate 5 x 3/2 using a number line? Write the product as an improper fraction and as a whole or mixed number.

    0 1 2 3 4 5 6 7 8 9 10

    0 1 2 3 4 5 6 7 8 9 10

    3/2 3/2 3/2 3/2 3/2

  • Jenniferpours2/3ofacupofwaterintoapotandrepeatsthis7times.Howmanycupsofwater,intotal,doesshepourintothepot?Useoneofthestrategies(grid,fractionstrips,ornumberline)toshowyouranswer.Writeitasamixednumber.

    Yourassignment:Pages49and50#3,5,6,8,13and16

  • About1/10ofCanadianswhoare12andolderdownhillski.About2/5oftheseskiersarebetween

    theagesof12and14.

    WhatfractionoftheCanadianpopulationbetweentheagesof12and14aredownhillskiers?

    IdentifytheKeyInformation

    1/10Canadiansolderthan12ski.

    2/5ofthe1/10areaged1214.

    Whatfractionofthe1/10areaged1214?

    MakeaPlan

    Multiply2/5by1/10.

    CarryoutthePlan

    Thisiswhatwearelearningtoday!

    1. Drawagridthatrepresentsthedenominator(5x10).

  • 3.Thisrectangleis .

    Itsareais2x1squaresoutofthetotal5x10squares.

    4.

    1/25Canadiansbetweentheagesof12and14downhillski.

  • Things to ponder...1.Howdoesthismodelshowbothand?

    2.Howcanyouuseamodeltodeterminethenumeratoranddenominatorofaproduct?

    3.Suggestapossibleprocedureformultiplyingtwofractionslessthan1.Whydoesthiswork?

    To multiply 2 fractions less than one you can:

    A.Drawthegrid.

    B.Multiplythenumeratorsanddenominators.

  • e.g.

    GridMethod

    1.Drawagridwiththedimensionsofthedenominators.

    2.Fillthegridwitharectanglethedimensionsofthenumerators.

    3.Rewritethefractionasthe .

    4.Writeinlowestterms.

    e.g.

    Multiplication

    1.Multiplythenumeratorsanddenominators.

    2.Rewriteinlowestterms.

  • Jacksonisawakefrom2/3oftheday.Hespends5/8ofthattimeathome.WhatfractionofthedayisJacksonawakeat

    home?

    TheGrade8classraised2/5ofthemoneyto

    supporttheschool'swinterproduction.TheGrade8boysraised2/3oftheGrade8

    money.Whatfractionofthewholeproductionfunddidthegrade8boysraise?

    Aboriginalpeoplesmakeupabout3/20ofthepopulationofManitoba.Ofthose,onlyabout1/3areunder15.WhatfractionofManitoba'stotalpopulationismadeupof

    Aboriginalpeoplesunder15?

    OnetwentiethofManitoba'spopulationismadeupofAboriginalpeoplesundertheageof15.

    Thegrade8boysraisedfourfifteenthsoftheproductionfund.

    Jacksonisawakeforfivetwelfthsoftheday.

    More Practice:

    pg 54

    1b, 2, 3, 4bc, 5, 6, 7, 8, 11 a

  • Aim: I can multiply mixed numbers and improper fractions.

    Fraction Products and Multiplying Fractions Greater than 1

    Thinkofastrategyyoumightusetosolvethisproblem?

    A large tub of popcorn holds 2 1/2 times as much as a smaller tub. Aaron has 1 1/2 large tubs.He is pouring the popcorn into smaller tubs to give to friends.

    How many small tubs will his popcorn fill?

    smaller large

  • Thinkaboutwhywewouldsetupthemodelinthisway.Howdothenumbersinthisproblemhelpyoudecidehowlargetomaketherectangles?

    AreaofAis1x2=2squareunits

    AreaofBis1x1/2=1/2squareunit

    AreaofCis1/2x2=1squareunit

    AreaofDis1/2x1/2=1/4squareunit

    Thetotalareais

    2+1/2+1+1/4=33/4squareunitsHecouldfill33/4smalltubs.

    Onestrategymightbetouseanareamodel.Weknowthisisamultiplicationproblembecausewehave11/2groupsof21/2.

    AB

    C D

    1

    1/2

    2 1/2

    Another strategy might be to set up a procedure.

    Turn the problem into an equation. 1 1/2 groups of 2 1/2 becomes 1 1/2 x 2 1/2. Having a mixed number can make it difficult to solve, so turn each mixed number into an improper fraction. 1 1/2 is the same as 3/2, and 2 1/2 is the same as 5/2. By doing this, it will be easier to multiply.

    3 5 2 2

    x = 3 x 52 x 2

    15 4

    = = 3 34

    Multiply the renamed fractions just like you would multiply fractions less than one.

  • 2 1/2 x 3 1/3 = (2 x 3) + (2 x 1/3) + (1/2 x 3) + (1/2 x 1/3) = 6 + 2/3 + 3/2 + 1/6(make 6 common = 6 + 4/6 + 1 3/6 + 1/6denominator) = 7 + 8/6 or 8 2/6 or 8 1/3

    Multiply 2 1/2 x 3 1/3 using area grids.

    3 1/3

    2

    1/2

    ( 3 x 2)

    3 x 1/2

    1/3 x 2

    1/3 x 1/2

    Tomultiply21/2x31/3asaprocedure,youcandothefollowing:

    212

    52

    3 13

    =

    = 103

    52

    10x 52 3

    x=3 x10

    =506 68 8= 3

    2 1

    Now,try5/8x61/2usingbothagridandaproceduretocalculate.Doyoucomeupwiththesameanswerforboth?

  • Usethestrategiesdiscussedinthislessontofindtheanswertotheproblem.

    Miriam is making 3 1/2 dozen cookies. If 2/7 of the cookies have icing, how many dozen cookies have icing?

    Today'sAssignment:

    Pages61and62

    #s5,7,8,10,12,14&16

  • Aim: I can use a sharing model to represent the quotient of a fraction divided by a whole number.

    Dividing Fractions by Whole Numbers

    Fourtenthsofthepossibledonorsstillhavetobecalled.Twoofthestudentsaregoingtosharethejob.

    Whatfractionofallthepossibledonorswilleachstudentbecalling?

    How

  • Thesameasthenumeratorofthefraction

    Howdoyouknowhowmanycounterstouse?

    Thenumberofsquaresisthesameasthedenominator.

    Tofindthesolution,weneedtodividethefractionbyawholenumber.

    Howdoweknowhowmanysquarestouseinthegridofthefraction?

    4 10

    2

    4102=

    210

    WhenIdivideby2,Iseparatethemodelinto2equalgroups.WhenImultiplyby2,Iaddthemodel2times.

    Whatdoyoudodifferentlytothegridmodelofthefractionwhenyoudivideitbyawholenumberthanwhenyoumultiplyitbyawholenumber?

    4 10

    2

  • Createagridandusethisstrategytosolvethisproblem.Remember,ifyouhave1/3,youaredividingby3.

    Allison had art class 9 out of the 20 school days last month. She worked with a partner about 1/3 of the time. For what fraction of the school days did she work with a partner in art?

    9 out of 20 is 9 209203 = =

    320

    9 3 20

    Allison worked with a partner for 3 of the 20 days.

  • How do we divide a fraction if the numerator is not divisible by the whole number?

    2/3 of a room still has to be tiled. Three workers are going to share the job. What fraction of the room will each worker tile if they all work at the same rate?

    23 3 = 23

    32 cannot be divided by 3 evenly. Since we are dividing fractions, we cannot have a decimal number. We need to find an equivalent fraction to 2/3 that can be divided by 3. An equivalent fraction to 2/3 would be 6/9. 6/9 can be divided by 3. 6__3

    9 = 2

    9

    Assignment:Page71#s4,6,7,9and10

  • Dividing Fractions Using a Related Multiplication

    Aim: Divide fractions using a related Multiplication.

    Allison has 2 large cans of paint. Nikita has 7/8 of a large can of paint. Each student is pouring paint into small cans that hold 1/3 as much as the large ones.

    How many small cans of paint will each student fill?

    Allison Allison Nikita

    Thinkofastrategyyoumightusetosolvethisproblem?

  • TofindouthowmanysmallcansIcanfill,Icandivide2by1/3

    Ineededtodivide2by1/3toseehowmanysmallcans(1/3thesizeofthebigcans)wouldbefilledby2largecans.

    2 = 2x

    Thisiscalledtakingthereciprocal.Thereciprocalisthefractionthatresultsfromswitchingthenumeratorandthedenominatorofthefractionontherightsideoftheequation.

    Flip rig

    ht sid

    e frac

    tion

    and Mu

    ltiply

    Ineededtodivide7/8by1/3toseehowmanysmallcanswouldbefilledbya7/8fulllargecan.

    TofindouthowmanysmallcansIcanfill,Icandivide7/8by1/3

    = x

    Wecannowmultiplystraightacross

    = =

  • Rahulhas2/3ofacontaineroftrailmix.Heisfillingsnackpacksthateachuseabout1/5ofacontainer.HowmanysnackcanRahulmake?

    Trythiswithapartner

    1) What is your initial amount?

    2) What is the amount they are being divided into?

    3) What is your equation going to look like?

    4) Which equation do we flip?

    Rahulhas2/3ofacontaineroftrailmix.Heisfillingsnackpacksthateachuseabout1/5ofacontainer.HowmanysnackcanRahulmake?

    Thisisreallyaskingwhatis2/3dividedby1/5

  • HomeworkPg.8586#2,3af,6ad,9a,13

  • Attachments

    MSOfficePNG.png

    MSOfficePNG12818.png

    MSOfficePNG30212.png

    SMART Notebook

    SMART Notebook

    SMART Notebook

  • OrderofOperations2.10

    Learner OutcomeUseorderofoperationsincalculationsinvolvingfractions

    TheOrderofThings...

  • WithaPartner,try:(6+9) X (8 - 3) 25 + 7 - 4 X 2 =

    Brackets

    = 15 X 5 25 + 7 - 4 X 2

    Multiply and Divide

    = 75 25 + 7 - 4 X 2 Multiply and Divide

    75 25 + 7 - 4 X 2 Multiply and Divide

    = 3 + 7 - 8 Add and Subtract

    = 3 + 7 - 8

    Add and Subtract= 10 - 8

    Add and Subtract= 2

    NowTry...

    EquililentFraction

    Reciprical

    Reduce

  • Target1Game

    Thegoalistocreateanequationwhosesolutionisasclosetooneaspossible

    Eachgroupcutsoutonefractionsheetandoneoperation

    sheet

    Ineachroundbothpartnerstake3

    fractioncardsandtwooperationcards

    Rearrangeyourfractionssotheyareasclosttoone

    aspossible

    ThepersonclosesttoonewinsthatroundThefirsttofiveroundswins!!

    Solve

  • YourAssignment

    Page90#1,3,6,7a13

  • Important Terms

    Fraction: One number written over another. The operation is to divide the top the bottom

    Numerator: Top number in a fraction

    Denominator: Bottom number in a fraction

    Mixed Fraction: Mix between a whole number and a fraction

    Improper fraction: When the numerator is larger than the denominator

    Chapter 2: Fractions January 26, 2011 3:41 PM

    Chapter 2 Page 1

  • "How Many Times Does the bottom number fit into the top?" This will be your whole number (left of your fraction)

    1.

    Find what's left over (Whole number times bottom number, subtracted from original top number). Put that number as a fraction over the original denominator.

    2.

    Fraction Conversation NotesJanuary 31, 2011 8:28 AM

    Chapter 2 Page 2

  • Chapter 2 Page 3

  • Chapter 2 Page 4

  • January 31, 2011 5:40 PM

    Chapter 2 Page 5

  • fractionaction

    Inserted from:

    Fraction ActionJanuary 31, 2011 5:24 PM

    Chapter 2 Page 6

    file://S:/XEROX-SCAN/fractionaction.PDF

  • fractionactionans Chapter 2 Page 7

  • fractionactionans

    Inserted from:

    Chapter 2 Page 8

    file://S:/XEROX-SCAN/fractionactionans.PDF

  • Chapter 2 Page 9

  • Fraction DiagramsJanuary 31, 2011 5:36 PM

    Chapter 2 Page 10

  • Chapter 2 Page 11

  • February 3, 2011 9:00 AM

    Chapter 2 Page 12

  • Chapter 2 Page 13

  • Chapter 2 Page 14

  • Chapter 2 Page 15

  • 2.1

    Inserted from:

    2.1February-06-11 11:32 AM

    Chapter 2 Page 16

    file://S:/Grade 8/GREVEBR/Math 8/CH 2/Scanning/2.1.PDF

  • Chapter 2 Page 17

  • 2.2

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    2.2February-06-11 11:32 AM

    Chapter 2 Page 18

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  • 2.3

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    2.3February-06-11 11:32 AM

    Chapter 2 Page 20

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  • 2.4

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    2.4February-06-11 11:32 AM

    Chapter 2 Page 22

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    2.5February-06-11 11:32 AM

    Chapter 2 Page 24

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  • February 9, 2011 9:11 AM

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  • Just like multiplying, convert all mixed fractions to improper fractions

    Take the reciprocal of the fraction you are dividing by and change the division sign to multiplication

    Top times top, bottom times bottom. Convert to a mixed fraction and reduce Done :)

    Dividing Mixed FractionsFebruary-09-11 7:32 PM

    Chapter 2 Page 29

  • Chapter 2 Page 30

  • Always Use BEDMAS to determine order of operations:

    B - BracketsE - ExponentsD - Division M - Multiplication A - AdditionS - Subtraction

    Order of OperationsFebruary-09-11 7:39 PM

    Chapter 2 Page 31

  • Chapter 2 Page 32

  • Chapter 2 Page 33

  • Chapter 2 Page 34

  • Chapter 2 Page 35

  • Chapter 2 Page 36

  • Chapter 2 Page 37

  • Chapter 2 Page 38

  • With a Partner:Cut out all fraction cards1.Place cards face down on a desk2.Each partner takes 3 fraction cards and 2 operation cards3.Each partner gets 1 set of brackets4.The goal is to arrange your fraction and operation cards to end up with an answer as close to 1 as possible

    5.

    Each win is worth 1 point, first to 5 points wins!6.

    Math Game: Target 1February 11, 2011 8:51 AM

    Chapter 2 Page 39

  • frac1

    Inserted from:

    February 17, 2011 9:03 AM

    Chapter 2 Page 40

    file://S:/XEROX-SCAN/frac1.PDF

  • frac2 Chapter 2 Page 41

  • frac2

    Inserted from:

    Chapter 2 Page 42

    file://S:/XEROX-SCAN/frac2.PDF

  • Chapter 2 Page 43

  • Chapter 2 Page 44

    introPage 1Page 2Page 3

    21Page 1Page 2Page 3Page 4Page 5Page 6

    22Page 1Page 2Page 3Page 4Page 5Page 6

    25Page 1Page 2Page 3Page 4

    26Page 1Page 2Page 3Page 4

    29Page 1Page 2Page 3Page 4Attachments Page 1

    30Page 1Page 2Page 3Page 4

    Chapter 2