PELANGI
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A perfect fusion of Thai Syllabus and Singapore Maths approach
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Textbook Prathomsuksa 2
Based on the Basic Education Curriculum B.E. 2551 (Revised Edition B.E. 2560)
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Textbook
Prathomsuksa 2 © 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
BDRC302031_GoGetMaths TB Prelimpage P2.indd 1
885-87220-0347-0 First Published 2022
5/11/2564 BE 12:00
Contents Chapter 1
Chapter 2
Chapter 3
Numbers to 1,000
1
Lesson 1 Lesson 2 Lesson 3 Lesson 4
2 7 14 19
Addition and subtraction within 1,000
21
Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7
22 26 31 33 37 41 44
51 Measuring length Units of length Comparing and ordering lengths Word problems
Mass Lesson 1 Lesson 2 Lesson 3 Lesson 4
Chapter 5
Adding two numbers without regrouping Adding two numbers with regrouping Adding three numbers Subtracting without regrouping Subtracting with regrouping Finding the unknowns Word problems
Length Lesson 1 Lesson 2 Lesson 3 Lesson 4
Chapter 4
Counting to 1,000 Comparing and ordering numbers Number patterns Even and odd numbers
52 56 58 63
67 Measuring mass Units of mass Comparing and ordering masses Word problems
68 72 73 78
Volume and capacity
81
Lesson 1 Lesson 2 Lesson 3 Lesson 4
82 84 88 94
Understanding volume and capacity Measuring volume and capacity Comparing and ordering volumes and capacities Word problems
Chapter 6
Chapter 7
Multiplication
97
Lesson 1 Lesson 2 Lesson 3 Lesson 4
98 101 111 118
Division Lesson 1 Lesson 2 Lesson 3 Lesson 4
Chapter 8
Chapter 9
Chapter 11
121 Meaning of division Division and multiplication Division Word problems
122 125 127 131
Mixed operations
135
Lesson 1 Lesson 2
136 139
Order of operations Word problems
Time Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5
Chapter 10
Meaning of multiplication Multiplication of a 1-digit number by a 1-digti number Multiplication of a 1-digit number by a 2-digit number Word problems
146 Telling and writing time Duration of events in hours and minutes Comparing and ordering duration of events Word problems Understanding calendars
147 156 161 166 172
Shapes and patterns
176
Lesson 1 Lesson 2
177 182
More 2D shapes Making patterns with shapes
Picture graphs
184
Lesson 1 Lesson 2
185 189
Reading picture graphs with scales Solving problems
Computational thinking
194
The big idea
Illustrates a scenario through which students can connect to the Chapter 5 chapter. Volume and capacity
Special Features
Computational thinking
Introduces a new approach for solving complex problems with confidence.
Which flask contains the most liquid? How do you find out?
Lesson 1
Understanding volume and capacity
Lesson 2
Measuring volume and capacity
Lesson 3
Comparing and ordering volumes and capacities
Lesson 4
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
Lesson 3
Breaking a complex problem into manageable, smaller problems
Division
Starting point
There are 5 apples. Can you divide the apples into 2 groups equally?
Learning to know
Learning to know
Introduces new concepts using the CPA approach with engaging illustrations.
Developing a set of step-by-step solution
Division without remainders
Abstraction
Challenges students with unconventional questions to develop higher-order thinking skills.
Focusing on relevant information, and removing irrelevant information
The teacher has 8 lollipops. She wants to divide them equally among 4 students. How many lollipops will each student get?
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. 194 | Mathematics Prathomsuksa 2
8÷4=2 Each student gets 2 lollipops. In this situation, the teacher will have no lollipop left after dividing them among the students. This type of division has no remainder.
Thinking corner
Pattern recognition Identifying similarities and differences, and observing similar patterns
Algorithms
If you were the teacher, how would you give out the lollipops and ensure each of the students gets the same number of lollipops? Chapter 7 | 127
Fun with Maths!
Allows students to explore mathematical concepts actively either as an individual or in groups.
1. Get into groups of 4. 2. Get 36 marbles. 3. Divide the marbles equally into 2 groups. How many marbles are there in each group? 4. Repeat step 3 with 3, 4 and 6 groups. Number of groups
2
3
4
6
Number of marbles in each group
1. There are 4 roses. Aom wants to divide the flowers equally between her 2 teachers.
4÷2= Each teacher will get
roses.
2. Mother has 9 cookies. She wants to split them equally onto 3 trays.
9÷3= Each tray will have 124 | Mathematics Prathomsuksa 2
cookies.
Try this
Provides various exercises to immediately evaluate students’ understanding.
Chapter 1
Numbers to 1,000
How many lollipops are there altogether?
Lesson 1
Counting to 1,000
Lesson 2
Comparing and ordering numbers
Lesson 3
Number patterns
Lesson 4
Even and odd numbers
Counting to 1,000
Lesson 1 Starting point
There are many candies. How do we count when the items are more than 100? Should we count in tens?
Learning to know
๑๐ ten
100
๑๐๐ one hundred
๒๐๐ two hundred
300
๓๐๐ three hundred
10
200
Counting to 1,000
2 | Mathematics Prathomsuksa 2
400
๔๐๐ four hundred
500
๕๐๐ five hundred
600
๖๐๐ six hundred
700
๗๐๐ seven hundred
800
๘๐๐ eight hundred
900
๙๐๐ nine hundred
1,000
๑,๐๐๐ one thousand Chapter 1 | 3
How many building blocks are there? We can count them in hundreds, tens and ones.
100
200
210
220
230
231
10
10
10
10
310
320
330
340
10
10
710
720
721
722
232
233
234
235
There are 235 building blocks.
How many candies are there?
100
100
100
100
200
300
341
342
343
There are 343 candies.
100
100
100
100
700
There are 726 candies. 4 | Mathematics Prathomsuksa 2
723
724
725
726
Learning to know
Place values
144424443 144424443 144424443 2 hundreds
258 = 2 hundreds 5 tens 8 ones 258 = 200 + 50 + 8
5 tens
8 ones
Hundreds 2
Tens 5
Ones 8
The digit 2 in 258 is in the hundreds place. Its value is 200. The digit 5 in 258 is in the tens place. Its value is 50. The digit 8 in 258 is in the ones place. Its value is 8.
1444442444443 1442443 1442443 9 hundreds
904 = 9 hundreds 4 ones 904 = 900 + 4
0 ten
Hundreds 9
4 ones
Tens 0
Ones 4
The digit 9 in 904 is in the hundreds place. Its value is 900. The digit 0 in 904 is in the tens place. Its value is 0. The digit 4 in 904 is in the ones place. Its value is 4.
Chapter 1 | 5
1. Count. Write in numerals and words. Thai numerals
Items 100
100
100
100
100
100
100
100
100
100
100
100
100
100
Hindu-Arabic numerals
Words
10
10
10
10
100
100
100
10
2. Fill in the blanks. (a)
hundreds
tens
one = 590
(b)
hundreds
tens
ones = 427
3. Fill in the blanks. 346
(a) The digit 3 in 346 is in the
place. Its value is
.
(b) The digit 4 in 346 is in the
place. Its value is
.
(c) The digit 6 in 346 is in the
place. Its value is
.
6 | Mathematics Prathomsuksa 2
Comparing and ordering numbers
Lesson 2 Starting point
There are 2 bowls of paper clips. Which has more paper clips? Which has fewer paper clips? How do you know?
Learning to know
250
180
Comparing numbers with different hundreds
Which number is greater, 213 or 312?
Hundreds 2
Tens 1
Ones 3
Hundreds 3
Tens 1
Ones 2
Hundreds 8
Tens 6
Ones 2
Compare the hundreds. 3 is greater than 2. So, 312 is greater than 213. Compare 734 and 862. Hundreds 7
Tens 3
Ones 4
Compare the hundreds. 7 is smaller than 8. So, 734 is smaller than 862. 734 < 862
or or or
8 is greater than 7. So, 862 is greater than 734. 862 > 734 Chapter 1 | 7