Second Term Lesson Note for Week Two
Class : Primary Four
Subject : Mathematics
Topic : Fractions (Equivalent, Addition and Subtraction of fraction)
Duration : 80 Minutes
Period : Double Period
Reference Book :
- New Method Mathematics for Primary Schools, Book 4, by Learn Africa.
- Lagos State Unified schemes of work for Upper Primary, Primary 4 – 6.
- Online Resources
Instructional Material : Chart showing description of equivalent, like and unlike fractions.
Previous Knowledge : Learners have been taught fractions and types of Fractions.
Learning Objectives : By the end of the lesson learners will be able to :
i. Explain equivalent fractions with examples
ii. Describe like and unlike fractions.
iii. Solve problems on addition and subtraction of Fractions.
Content :
There are two kinds of fractions. These are :
Like Fractions : These are fractions that have the same denominators. E.g. 1/3 and 2/3, 2/7 and 4/7, 3/10 and 6/10, etc.
Unlike fractions : These are fractions that have different denominators. E.g. 2/3 and 1/4, 2/5 and 3/7, 3/4 and 5/9, etc.
Equivalent fractions : This is when two fractions are said to be equal.
When finding equivalent fractions of any given fractions, we either use any method.
(a) Multiplication of number
(b) Division of number
Considering the pair of equivalent fractions, if the fraction on the left hand side is small, the equivalent will be gotten by multiplying a common factor.
For examples :
1. 1/2 = 2/4 = 3/6 = 4/8 = 6/12
2. 3/4 = 9/12 = 18/24 = 24/32
3. 2/5 = 4/10 = 8/20 = 16/40
The equivalent fractions of above examples are derived by multiplying the given fractions with a common multiple.
We can also use division method using a common factors. For examples :
1. 36/48 = 12/16 = 6/8 = 3/4
2. 24/72 = 12/ 36 = 6/18 = 3/9
Addition and Subtraction of Fractions.
Addition of Fractions
When adding fractions, we first determine the L. C. M. of the denominators of the given fractions.
Use each of the denominator to divide the L. C. M.
Then, multiply the result of the division with the numerator of each fraction.
Finally, add the values realised, all over the denominator.
For examples :
1. 1/4 + 1/2 = (1 + 2) / 4 = 3/4
2. 3/4 + 1/5 = (15 + 4) / 20 = 19/20
3. 5 1/2 + 3 1/5 = 8 (5 + 2)/10 = 8 7/10
Subtraction of Fractions :
When subtracting fractions, we first determine the L. C. M. of the denominators of the given fractions.
Use each of the denominator to divide the L. C. M.
Then, multiply the result of the division with the numerator of each fraction.
Finally, subtract the values realised, all over the denominator.
For examples :
1. 3/4 – 1/2
= (3 – 2)/4
= 1/4
2. 3/5 – 1/6
= (18 – 5) /30 =
13/30
3. 7 2/3 – 4 1/4
= 3 (8 – 3)/12
= 3 5/12
Evaluation :
1. Find the equivalent fraction of the given fractions.
i. 1/3 = ( )/15 ii. 4/7 = 16/( )
iii. 24/48 = 4/( ) iv. 25/ 100 = ( )/4
2. Simplify the following fractions :
i. 5 1/2 + 2 2/5
ii. 12 3/4 – 7 1/2
iii. 3 1/3 + 6 2/7
iv. 4 4/5 – 3 1/4
CONCLUSION : The teacher summarizes the lesson by emphasizing on the important point for a better understanding. He marks the learners notebooks.