A DETAILED LESSON PLAN IN MATHEMATICS FOR GRADE-FOUR
I. OBJECTIVES
At the end of a 45-minute period, the grade four pupils will be able to: 1. Add and subtract fractions with the same denominators,
2. Add and subtract fractions with dissimilar denominators,
3. Add and subtract mixed numbers with similar denominators, and
4. Add and subtract mixed numbers with dissimilar denominators with 75% proficiency level.
II. SUBJECT MATTER
ADDING AND SUBTRACTING OF FRACTIONS A. References
Liking Mathematics in the Grade School: Textbook in Mathematics for Grade-Four by Prepotente et.al.
21st Century Mathematics (6) by Villame et.al.
B. Materials
Power point presentation, visual aids C. Ideas
To add/subtract fractions with similar denominators, we add/subtract the numerator and write the sum/difference over the same denominator.
To add/subtract fractions with dissimilar denominators, first find the smallest equivalent fractions by using the least common multiple (LCD) to rename the dissimilar fractions into similar fractions and then proceed as in adding/subtracting fractions with the same denominator.
To add/subtract mixed numbers with similar denominators, we add/subtract the whole numbers, then the numerators and retain the denominator.
To add/subtract mixed numbers with dissimilar denominators, change dissimilar fractions to similar fractions. Add/subtract the whole numbers, and then the numerators and copy the denominator.
D. Processes
Identifying, adding, subtracting E. Value
Small parts are necessary to make-up a whole. III. PROCEDURE
A. Pre-assessment 1.Prayer
2.Checking of attendance 3.Review of the past lesson B. Motivation
A song about mathemetics C. Lesson proper
Teacher Activity Pupil Activity
Class, do you love to eat chocolates? Yes Ma’am Who wants to eat a chocolate? We’d love to, Ma’am. I have here a bar of chocolate and I
am going to divide it equally into four parts. (Slice).
So I have now 4 slices or 4/4 of chocolate.
(Give the 2/4 of the apple to two pupils, 1/4 each). So I have given Mario ¼ of the chocolate
and another ¼ to Rowena. How much
chocolate have I given all in all and how 2/4 given
much is left? 2/4 left
Yes Very Good! I sliced the chocolate
into fourequal parts so we get 4/4 or 1 of course and I gave Mario and Rowena ¼ each of
the chocolate. So ¼ + ¼ , we get 2/4 or ½ and the parts that is left for me is also 2/4 0r ½ .
If we are going to add the parts of apple that I have given to Mario and Rowena
and the parts left for me, how much will it
be all in all? 4/4 or 1
Now class, do you have any idea of what
will be our topic for today? Adding and
ing of fraction
Exactly class. Today, we will be discussing how to add and subtract fractions. And I want you to meet the following
objectives which are to: add and subtract fractions with the same denominators, add and subtract fractions with dissimilar denominators, add and subtract mixed numbers with similar denominators, and add and subtract mixed numbers with dissimilar denominators with 75% proficiency
level. Can I expect that from you? Sure Ma’am. So we have here different rules in
adding and subtracting of fractions. Take note that I am going to give you a quiz after this so you better bear with me class, listen carefully as I am going to present and discuss each rule one after the other.
To add fractions with similar denominators,we simply add the numerators andwrite the sum over the same denominator.
Dulce ate ⅖ of the cake in the morning and ⅕ in the afternoon. How much cake was eaten by her?
What is asked in the problem? The amount of cake eaten by Dulce. What are given? 2/5 cake in the morning
and 1/5 in the afternoon. So we are going to add the given
fractions to answer what is asked in the problem. As what is stated in the rule, we simply add the numerators and write the sum over the same denominator in adding of similar fractions. So we simply add 2 and 1 which is equal to 3 and write it over the same denominator which is 5. And the answer is 3/5.
Did you get it? Yes Ma’am.
So let’s proceed.
To subtract fractions with similar denominators, we simply subtract the numerators and write the difference over the same denominator.
This is somewhat similar as in adding of fractions with similar denominators. The only difference is we are going to subtract the numerators instead of adding A water tank was ⅞ full of water. After a day of use, it was ⅜ full. How much water was used during the day?
What is asked? The amount of water that
was used during the day. What are given? 7/8 full of water and 3/8 full
To find the amount of water that was used during the day, we are going to subtract 3/8 from 7/8. So simply subtract the numerators 7-3 is equal to 4 and write it over the same denominator which is 8 and then we get 5/8.
To add fractions with dissimilar denominators, rename the dissimilar fractions into similar
fractions by finding the (LCD) and then proceed as in adding fractions with the same denominator.
Mother used ⅗ liter of cooking oil last month and⅔ liter this month. How much did she use in two months?
What is asked? The amount of cooking oil mother used in two months. What are given? 3/5 liter of cooking oil last
month and 2/3 liter this month. How do we add 3/5 and 2/3?
Examine their denominators. Do they
have the same or what? Different/dissimilar Obviously! So the first we need to find
The LCD or (Least Common Denominator).
What is the LCD of 5 and 3? 15 Aha! And we are going to use 15 to
rename these dissimilar fractions into similar fractions. And then we get 9/15 and 10/15 so we can now add these similar fractions to get the answer which is 19/15 or 1 4/15.
To subtract fractions with dissimilar denominators, rename the dissimilar fractions into similar fractions by finding the (LCD) and then proceed as in
subtracting fractions with the same denominator.
Aling Dionisia, a stuffed-toy maker, uses 5/9 bag of stuff for a dog and 4/6 bag of stuff for a cat. How much more stuff does she use for a dog than for a cat.
What is asked? The amount of stuff she use for a dog than for a cat. What are given? 4/6 bag of stuff for dog and
5/9 bag of stuff for a cat. Like adding of fractions with
dissimilar denominators, we need To find the LCD in order to rename these fractions into similar fractions allowing us to proceed in subtraction.
What is the LCD of 6 and 9? 18
So the fractions involved are now
12/18 and 10/18. And to answer what is asked in the problem we are going to subtract 10/18 from 12/18 and we get 2/18 or 1/9.
.
To add mixed numbers with similar denominators, we add the whole
the denominator.
What do you mean by mixed numbers? A mixed number is composed of a whole number and a fraction. Yes, exactly! We have discussed
that already.
Jebs and Brion helped in the “Operation Linis” on Saturday and Sunday. John mowed 3⅓ of the lawn and Bob mowed 4⅓ of it .What part of the lawn did the two boys mow together?
What is asked? The part of the lawn the two boys mow together.
What are given? John mowed 3⅓ of the
lawn and Bob mowed 4⅓ of it.
3⅓ and 4⅓ are examples of mixed numbers with similar denominators of which we can just add directly without the need of finding an LCD.
We automatically add the whole numbers- 3+4=7 and then the numerators- 1+1=2 and write it over the same denominator- 3. The part of the lawn the two boys mowed together is 7 2/3.
To subtract mixed numbers with similar denominators, we subtract the whole numbers, then the numerators and retain the denominator.
A vendor sold 316/7 kilograms of mangoes on Monday and 26 5/7 kilograms on Tuesday. How much more kilograms of mangoes did she sell on Monday than on Tuesday?
What is asked? The amount of mangoes
in kls that she sell more
on Monday than on Tuesday.
What are given? 31 6/7kls of mangoes on Monday and 26 5/7 kls on Tuesday.
As stated in the rule we are going to subtract first the whole numbers-31-26=5, and then the numerators-6-5=1 and write it over the same denominator 7. And we get the answer which is 5 1/7.
To add mixed numbers with dissimilar denominators, change dissimilar fractions to similar fractions. Add the whole numbers, and then the numerators, and copy the denominator.
Vener and Edmund opened a vegetable stand in a supermarket. On opening day, they sold 4 5/8 bushels of corn and sold 3 4/6 bushels on the following day. How much corn was sold in two days?
What is asked? The amount of corn
that was sold for two days.
What are given? On opening day, they
sold 4 5/8 bushels of corn and sold 3 4/6 bushels on the following day
How are we going to change dissimilar
fractions into similar fractions? find the LCD Precisely! And what is the LCD of
8 and 6? 48
Through obtaining the LCD of dissimilar fractions, we can derived its similar fractions and then perform the indicated
operation. 4 5/8 and 3 4/6 = 4 30/8 and 3 24/8. When added, 4+3=7(whole numbers) and 54/8 (similar fractions) we get 7 54/8.
To subtract mixed numbers with dissimilar denominators, change
dissimilar fractions to similar fractions. Subtract the whole numbers, and then the numerators, and copy the denominator. Mang Tony is a candle maker. He had 5 3/4 disks of wax. He used 4 2/5 of them. How much wax does he have left?
What is asked? The amount of wax
he have left.
What are given? He had 5 2/5 disks
of wax and he used 4 3/4 of them.
What is the LCD of 4 and 5? 20
Through the use of LCD we can now derived similar fractions where we can apply operations directly. In this case the fractions that we derived are 5 15/20 and 4 8/20. Subtract the whole numbers- 5-4=1 and then the numerators-15-8=7 and write it over the same
denominator 20. The answer is 1 7/20. Deductive Method
IV. EVALUATION
Direction: Solve each problem.
1. Julie bought ½ meter of red ramie cloth for her table napkins and 3/6 white ramie cloth for placemats. How many meters of cloth did she buy?
2. Mrs. Robles baked 1⅔ dozen cookies. She brought ¾ dozen to school for her friends. How many dozen of cookies were left?
V. ASSIGNMENT
Direction: Perform the indicated operation. a. 1 2/5+3/5
b. 2 ¼ - 2/4 c. 1-6/6
