LESSON NOTES ON MULTIPLICATION AND DIVISION OF FRACTIONS

SUBJECT: NUMBER THEORY
TOPIC: FRACTIONS
LESSON: MULTIPLICATION AND DIVISION OF FRACTIONS
PREVIOUS  KNOWLEDGE: STUDENTS CAN ADD AND SUBTRACT FRACTIONS
LESSON OBJECTIVES:By the end of the lesson, students should be able to multiply or divide any group of fractions, convert f fractions to vulgar fractions and vice versa.
TEACHING AIDS:Cardboard paper with some fractions already solved on.
TEACHING METHOD: Demonstration, Questioning, and Assignment.
GRADE LEVEL:7
,t: 45 minutes
DATE;01/05/2019
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INTRODUCTION:
Evaluate the following. i) 2/3+1/2 , ii) 1/3-4/5.
PRESENTATION:
Fractions are multiplied or divided like whole numbers but wit some little adjustments.
a) Multiplication of Fractions : To multiply fractions , multiply numerators and denominators.
     Example 1:Evaluate and simplify as far as possible each of the following.
       i) 2/3×4/5,  ii)1/7×5/6, iii) 8/3×6/5,  7/4×2/3.
                            Solution
       i) 2/3×4/5=8/15.
      ii) 1/7×5/6=5/42.
     iii) 8/3×6/5=48/15
           8/3×6/5=16/5.
     iv ) 7/4×2/3=14/12
            7/4×2/3=7/6.
b) Division of Fractions: To divide two fractions, invert the divisor and change the operation from division to multiplication and proceed as in multiplication above.
   Example1: Evaluate and simplify your result as far as possible in each of the following:
       i)1/3÷4/5, ii) 3/4÷1/6, iii) 7/4÷2/3,  iv) 8/3÷4/5.
                                   Solution
 i)1/3÷4/5=1/3×5/4
    1/3÷4/5=5/12.
 ii) 3/4÷1/6=3/4×6/1
      3/4÷1/6=18/4
      3/4÷1/6=9/2.
iii) 7/4÷2/3=7/4×3/2
       7/4÷2/3=21/8.
iv) 8/3÷ 4/5=8/3×5/4
      8/3÷4/5=40/12
      8/3÷4/5=10/3.
The fractions treated so far are called VULGAR FRACTIONS. We are going to the next group of fractions called DECIMAL FRACTIONS.
          DECIMAL FRACTIONS: This is a fraction expressed in tenths, hundredths, thousandth etc. Examples here are 0.2, 0.25, 0.625 etc.We can convert from decimal fractions to vulgar fractions and vice versa.
           Example: a)Change each of the following to vulgar fractions; i) 0.2, ii) 0.25, iii) 0.36
                            b) Change each of the following to decimal fractions; i) 2/5, ii) 8/25 .
                          Solution.
a) i) 0.2= 2/10
        0.2=1/5.
   ii) 0.25=25/100
        0.25=1/4.
  iii) 0.36=36/100
      0.36=9/25.
b) i) 2/5=0.4 by long division method.
    ii) 8/25=0.32 by long division method.

            EVALUATION:
Evaluate and simplify your answer to its lowest term in each of the following:
a) i) 3/8×1/5, ii)7/2×13/5, iii) 2/3÷8/11, iv) 7/2÷13/5
b) Change to vulgar fraction; i) 0.32,
c) Change to decimal fraction; i)5/8

                SUMMARY:
>When multiplying fractions, multiply numerators separately from denominators.
> When dividing fractions, change the operation from division to multiplication and invert the divisor the proceed as though you were multiplying.
>To change a decimal fraction to vulgar, move the decimal point to the right hand side of the number in question. Each digit crossed by the decimal point is equal to a tenth.It means 0.2=2/10, 0.24=24/100, etc.
>To change from vulgar fraction to decimal fraction use long division.

             CONCLUSION:
Assignment:Evaluate and simplify each of the following:
 i) 11/4× 1/5, ii) 2/7÷4/3  iii) (2/3×1/4)÷(15/4×5/2) iv) (3/5+1/3)×3/5, v)(3/4-1/3)÷3/4

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