I. Objectives:
Given varied activities, the grade 3 pupils, with at least 80% accuracy are expected to:
a. determine the parts of a subtraction equation;
b. apply the concept of subtraction in word problem;
c. supply what has been asked in every problem;
II. Subject Matter:
Topic: Concept of Subtraction
Values Infused: Honesty
Skills: Subtracting
III. Materials:
4 sets of Darts, $ cards with questions, manila paper for the word problem, flash cards, 50 fruits or vegetables and basket chart
References:
Mathematics for Changing World 3
(Norma M. Abracia, Ed. D. et, al. pp.52-55)
Mathematics for Global Challenges 3
(Norma Abracia pp. 79-83)
IV. Procedure:
A. Drill
The teacher will present a basket chart to the class with 50 kinds of fruits and vegetables. Let the students count all the fruits or vegetables in the basket. Ask for volunteers to pick the number of fruits or vegetables asked by the teacher and let the whole class identify how many fruits or vegetables are left. repeat the procedure until there is no more fruits or vegetables left. all students are given a chance to pick fruits or vegetables in the basket.
50 - 5 = 45 45-7 = 38 38-9 = 29 ......
B. Review:
Who can share what was discussed yesterday? what do you call the steps in solving problems? kindly enumerate the steps. Present the 4 cards with corresponding questions after grouping the class into 4 groups. each group must have a representative to answer the question in the board while the rest of the member of each group will answer in their seats following the Polya's 4 steps in solving problem solving.
1. Edwin gathered 968 mangoes on Friday, 1263 on Saturday and 1136 on Sunday. How many mangoes did he gathered in 3 days?
2. Nancy baked 57 cupcakes. Andi baked 27 cupcakes more than Nancy. How many cupcakes did Andi baked?
3. Imelda gave 18 roses to her mother. she had 19 roses left. How many did she have at first?
4. Ritzi walked a distance of 5673 meters on Saturday and 6898 meters on Sunday. How far did she walk in two days?
C. Lesson Proper:
1. Motivation
There will be a dart game and the class will be grouped into four groups. Each group are given initial 150 points. Every points of each group got is going to be subtracted to the initial points which is 150. each member of the group is expected to participate. the game will last for only 5 minutes. after the allotted time given by the teacher, the group who had the got the smallest number will be announced as the winner, thus they will receive extra points.
2. Presentation
The teacher will present the numbers got by each group. let see what group who got the smallest number. The whole class will help their teacher in deducting the numbers they got the initial point which is 150.
What we did as we are deducting numbers to the initial point? (simply subtracting)
Subtraction is the opposite operation of addition.
3. Discussion
The teacher will mount a word problem to the board.
"Liam has 123 pesos. he wants to buy a gift for his mother that costs 248 pesos. how much more does he need to save?
In solving this problem we were going to use the Polya's 4 steps in problem solving. What are the 4 steps? (Understand, Plan, Solve, Look back). The teacher will write all the steps on the board and ask for volunteers to answer to every steps with guidance from the teacher.
1. Understand
Given:
123 pesos - amount of money Liam has
248 pesos - cost of the gift that Liam wants to buy for his mother
Asked: amount that Liam needs to save
2. Plan
What operation to be used? Subtraction
What equation will be used to solve the problem?
248 pesos - 123 pesos = amount that Liam needs to save
3. Solve
Apply the equation to solve.
248 - 123 = 125 pesos
Therefore: Liam needs 125 pesos
4. Look back
Did your answer the question in the problem?
Is the answer reasonable? (let the student explain his or her answer)
4. Comparison
What do we call 248 pesos in the problem or the number from which we subtract? (minuend) What do we call 123 pesos in the problem, or the number that we subtract? (subtrahend) what do we call 125 pesos, or the answer in subtraction? (difference)
The teacher will let the students read the words; minuend, subtrahend, and difference, and let the students identify that these three words are part of subtraction equation. How do we know that you really got the correct answer? We were going to , what? (to check) How we were going to check? (apply addition) What number we were going to add? (123 and 125) 123 and 125, what part are they belong in subtraction equation? (123 is the subtrahend and 125 is the difference)
5. Generalization
What steps we were going to follow in solving problem especially in subtraction? (Polya's 4 steps in problem solving) Enumerate the 4 steps? (understand, plan, solve and look back) Let the students identify what has been asked in every step. after which let the students name the three parts of subtraction equation. (minuend, subtrahend, and difference) The teacher will present a Flash card and let the students name the number which is the minuend, subtrahend, and the difference.
6. Fixing of Skills
6.1. The teacher will present flash cards and let the students subtract orally.
6.2. Answer the Following equation
1. 18 -9 = 2. 17 - 8 = 3. 16- 8 = 4. 15 - 9 =
5. 11 - 4 =
6.3. Complete each equation by writing the missing part.
1. 26 - __ = 10 2. 19 - ___ = 9 3. ___ - 10 = 7
4. 20 -13 = ___ 5. ___ - 4 = 6
IV. Evaluation
Directions: Solve the following equation. Write your answers on the space provided.
a. 33 - 23 =___
b. 94 - 73 =___
c. 23 - 19 = ___
d. 81 - 80 = ___
e. 22 - 18 =___
f. 36 -36 = ___
g. 35 -8 = ___
h. 56 -51 =___
i. 37 -18 = ___
j. 33- 28 = ___
V. Assignment:
Answer pages 81- 82, Skill Builders B and C in your Math Book 3.
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