Textbook
Prathomsuksa 3 © Pelangi Publishing (Thailand) Co., Ltd. 2022 All rights reserved. No part of this publication may be reproduced, stored in any retrieval system or transmitted in any form or by any means without permission of Pelangi Publishing (Thailand) Co., Ltd. 2022
BDRC303031_GoGetMaths TB Prelimpage P3.indd 1
885-87220-0348-7 First Published 2022
5/11/2564 BE 12:00
Contents Chapter 1
Chapter 2
Chapter 3
Chapter 4
Numbers up to 100,000
1
Lesson 1 Lesson 2 Lesson 3
2 7 12
Addition and subtraction within 100,000
15
Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7
16 19 22 24 27 31 33
37
Lesson 1 Lesson 2 Lesson 3
38 42 45
Multiplication by a 1-digit number Multiplication of 2-digit numbers Word problems
Division
47 Division without regrouping Division with regrouping Finding the unknowns in multiplication and division Word problems
Length Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6
Chapter 6
Adding two numbers without regrouping Adding two numbers with regrouping Adding three numbers Subtracting without regrouping Subtracting with regrouping Finding the unknowns in addition and subtraction Word problems
Multiplication
Lesson 1 Lesson 2 Lesson 3 Lesson 4
Chapter 5
Counting to 100,000 Comparing and ordering numbers Number patterns
64 Measuring length Units of length Addition and subtraction involving length Multiplication and division involving length Comparing and ordering lengths Word problems
Mass Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6
48 54 59 61
65 70 73 75 78 82
86 Measuring mass Units of mass Addition and subtraction involving mass Multiplication and division involving mass Comparing and ordering masses Word problems
87 91 93 95 98 101
Chapter 7
Chapter 8
Volume and capacity
105
Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6
106 111 114 116 118 122
Fractions Lesson 1 Lesson 2 Lesson 3 Lesson 4
Chapter 9
Chapter 11
Chapter 13
Understanding fractions Comparing and ordering fractions Addition and subtraction of fractions Word problems
127 131 135 138
140 Recognizing money Telling the amount of money Comparing amounts of money Addition and subtraction involving money Multiplication and division involving money Word problems Recording expenditure
141 144 149 152 154 156 158
Mixed operations
163
Lesson 1 Lesson 2
164 166
Order of operations Word problems
Time Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7 Lesson 8
Chapter 12
126
Money Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7
Chapter 10
Measuring volume and capacity Units of volume and capacity Addition and subtraction involving volume and capacity Multiplication and division involving volume and capacity Comparing and ordering volumes and capacities Word problems
171 Telling and writing time using 12-hour clock system Units of time Duration of events in hours and minutes Addition and subtraction involving time Multiplication and division involving time Comparing and ordering duration of events Word problems Activity records
172 178 180 183 185 187 190 193
Symmetry
198
Lesson 1 Lesson 2
199 201
Understanding symmetry Number of lines of symmetry
Data handling
203
Lesson 1 Lesson 2 Lesson 3
204 208 214
Collecting and categorizing data Reading and constructing picture graphs Reading and constructing one-way tables
Computational thinking
219
The big idea
Illustrates a scenario through which students can connect to the chapter.
Chapter 3
Multiplication
Computational thinking
Special Features
Introduces a new approach for solving complex problems with confidence.
There are 80 boxes. Each box contains 16 mobile phones. How many mobile phones are there altogether?
Lesson 1
Multiplication by a 1-digit number
Lesson 2
Multiplication of 2-digit numbers
Lesson 3
Word problems
Starting point
Provides questions to initiate thinking and jump-start learning.
Computational thinking is not about programming a computer or thinking like a computer. It is rather a set of systematic approaches to solving problems. Then, we can present the solutions in a way a computer or a human or both can understand. There are four skills or elements in computational thinking.
Decomposition Breaking a complex problem into manageable, smaller problems
Number of lines of symmetry
Lesson 2 Starting point
2 lines of symmetry are drawn on the square. Are there any more lines of symmetry?
Learning to know
Introduces new concepts using the CPA approach with engaging illustrations.
Thinking corner
Challenges students with unconventional questions to develop higher-order thinking skills.
Learning to know
Developing a set of step-by-step solution
Abstraction
Number of lines of symmetry
Focusing on relevant information, and removing irrelevant information
Some shapes have many lines of symmetry.
A rectangle has 2 lines of symmetry.
This shape has 2 lines of symmetry.
Pattern recognition Identifying similarities and differences, and observing similar patterns
Algorithms
With this new approach, we will be able to tackle unfamiliar and complex problems with confidence. It trains us to analyze information and deal with problems across disciplines. It will help us see a relationship between the school and the outside world.
This triangle has 3 lines of symmetry.
Computational thinking |
ABCDEFGHIJKLMN OPQRSTUVWXYZ
219
Fun with Maths!
Analyze the capital letters. Which letters have 1 line of symmetry? Which letters have 2 lines of symmetry? Chapter 12 | 201
Allows students to explore mathematical concepts actively either as an individual or in groups.
1. Get in groups of 4. 2. The first student uses the clock to show the time. 3. The second student writes the time. 4. The third and fourth students read out the time in different ways. 5. The first student determines if they are correct. 6. Repeat by switching roles.
1. Draw the hands on the clock.
Try this
(b)
(a)
Twenty minutes past nine
Provides various exercises to immediately evaluate students’ understanding.
A quarter to two
2. Write the time in a.m. and p.m. (a) In the morning
(b) In the evening
Chapter 11 | 177
Chapter 1
Numbers up to 100,000
This stadium is so big. It can accommodate up to 25,000 spectators.
Lesson 1
Counting to 100,000
Lesson 2
Comparing and ordering numbers
Lesson 3
Number patterns
Sg Maths TB P3 Chpt1-4 text.indd 1
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Lesson 1
Counting to 100,000
Starting point
Each box contains 1,000 marbles. How do we count the number of marbles in all the boxes? Should we count in hundreds or thousands? Counting on from 1,000
Learning to know
1
1
1
1
1
1
1
1
1
1
10
10 ones make 1 ten.
10
10
10
10
10
10
10
10
10
10
100
10 tens make 1 hundred.
100
100
100
100
100
100
100
100
100
100
10 hundreds make 1 thousand.
1,000
2 | Mathematics Prathomsuksa 3
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1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
1,000
10 thousands make 1 ten thousand. Count on: 1,000, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10,000
10 ten thousands make 1 hundred thousand. Count on: 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000
10,000 10,000
20,000 10,000
1,000 1,000 1,000
100
23,100
100
23,200
23,000 22,000 100
23,300
100
23,400
21,000
100,000
10 23,430 1
23,431
1
23,432
10 23,420 10 23,410
๒๓,๔๓๒
23,432 ( ) Twenty-three thousand four hundred and thirty-two
Chapter 1 | 3
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10,000
1,000
1,000
100
100
10
10,000
1,000
1,000
100
100
10
10,000
1,000
100
100
10
10,000
1,000
100
100
10
10,000
1,000
100
1
10
๕๗,๙๕๑
57,951 ( ) Fifty-seven thousand nine hundred and fifty-one 10,000
10,000
1,000
1,000
100
100
10
1
10,000
10,000
1,000
1,000
100
100
10
1
10,000
10,000
1,000
1,000
100
100
10
1
10,000
10,000
1,000
100
100
10
1
1,000
100
10,000
1
๙๘,๙๔๕
98,945 ( ) Ninety-eight thousand nine hundred and forty-five
1. Work in pairs. 2. Write a number not more than 100,000. 3. Your partner will display the number discs representing the number and say it out. 4. Check his or her answer. 5. Switch roles and repeat for 4 times.
Twenty-one thousand and thirty-two Correct!
4 | Mathematics Prathomsuksa 3
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Learning to know
Place values 31,487 100
10
10
1
1
10,000
100
10
10
1
1
10,000
100
10
10
1
100
10
1
10
1
10,000
1,000
Ten thousands (TTh)
Thousands (Th)
Hundreds (H)
Tens (T)
Ones (O)
3
1
4
8
7
31,487 = 3 ten thousands 1 thousand 4 hundreds 8 tens 7 ones 31,487 = 30,000 + 1,000 + 400 + 80 + 7 The digit 3 in 31,487 is in the ten thousands place. Its value is 30,000. The digit 1 in 31,487 is in the thousands place. Its value is 1,000. The digit 4 in 31,487 is in the hundreds place. Its value is 400. The digit 8 in 31,487 is in the tens place. Its value is 80. The digit 7 in 31,487 is in the ones place. Its value is 7. 75,169 Ten thousands (TTh)
Thousands (Th)
Hundreds (H)
Tens (T)
Ones (O)
7
5
1
6
9
75,169 = 7 ten thousands 5 thousands 1 hundred 6 tens 9 ones 75,169 = 70,000 + 5,000 + 100 + 60 + 9 What is the value of each digit in 75,169? Chapter 1 | 5
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1. Count. Write in numerals and words. (a)
10,000
1,000
100
10
1
10,000
1,000
100
10
1
10,000
1,000
100
10
1
10,000
1,000
100
10
1,000
(b)
Thai numerals: Hindu-Arabic numerals: Words:
10
10,000 10,000
1,000 1,000
10
1
10,000 10,000
1,000 1,000
10
1
10,000
1,000 1,000
10
1
10,000
1,000 1,000
10
1
10,000
1,000
10
1
1
Thai numerals: Hindu-Arabic numerals: Words:
2. Fill in the blanks. ten thousand
thousands
hundreds
tens
ones = 14,873
ten thousands
thousands
hundred
tens
ones = 57,084
3. Fill in the blanks.
18,546
(a) The digit 1 in 18,546 is in the
place. Its value is
.
(b) The digit 8 in 18,546 is in the
place. Its value is
.
(c) The digit 5 in 18,546 is in the
place. Its value is
.
(d) The digit 4 in 18,546 is in the
place. Its value is
.
(e) The digit 6 in 18,546 is in the
place. Its value is
.
6 | Mathematics Prathomsuksa 3
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Comparing and ordering numbers
Lesson 2 Starting point
Box A contains 4,152 marbles. Box B contains 4,452 marbles. How do we know which box contains more marbles?
Comparing numbers with different thousands and ten thousands
Learning to know
Compare 7,418 and 6,263. Th
H
T
O
Th
H
T
O
7
4
1
8
6
2
6
3
Compare the thousands. 7 is greater than 6. So, 7,418 is greater than 6,263. 7,418 > 6,263
or or or
6 is smaller than 7. So, 6,263 is smaller than 7,418. 6,263 < 7,418
Compare 67,548 and 87,681. TTh
Th
H
T
O
TTh
Th
H
T
O
6
7
5
4
8
8
7
6
8
1
Compare the ten thousands. 6 is smaller than 8. So, 67,548 is smaller than 87,681. 67,548 < 87,681
or or or
8 is greater than 6. So, 87,681 is greater than 67,548. 87,681 > 67,548 Chapter 1 | 7
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