Go Get Maths Textbook P5 samplebook

Textbook

Prathomsuksa 5 © 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

BDRC305031_GoGetMaths TB Prelimpage P5.indd 1

885-87220-0360-9 First Published 2022

24/1/2565 BE 12:02

Contents Chapter 1

Chapter 2

Addition and subtraction of fractions

1

Lesson 1 Lesson 2 Lesson 3 Lesson 4

2 4 10 16

Multiplication of fractions

21

Lesson 1 Lesson 2 Lesson 3 Lesson 4

22 24 29

Lesson 5

Chapter 3

Chapter 4

Chapter 5

Fraction of a set Multiplication of a fraction by a whole number Multiplication of fractions Multiplication of a mixed number by a whole number, and mixed numbers Word problems

34 37

Division of fractions

41

Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5

42 44 47 50 53

Reciprocals Division of a fraction by a whole number Division of a whole number by a fraction Division of fractions Word problems

Mixed operations of fractions

57

Lesson 1 Lesson 2

58 61

Order of operations Word problems

Decimals Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5

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Fractions and division Comparing and ordering fractions Addition and subtraction of fractions Word problems

68 Estimation of decimals Multiplication of decimals Division of decimals Decimals and fractions Word problems

69 73 80 86 88

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Chapter 6

Chapter 7

Chapter 8

Chapter 9

Chapter 10

Chapter 11

Chapter 12

Percentages

91

Lesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5

92 94 96 99 103

Percentages Percentages as fractions and decimals Fractions and decimals as percentages Percentage of a quantity Word problems

Units of length and mass

108

Lesson 1 Lesson 2

109 114

Conversion between units Word problems

Volume and capacity

117

Lesson 1 Lesson 2 Lesson 3

Volume and capacity of a cuboid Volume of a liquid Word problems

118 126 129

Perpendicular lines and parallel lines

133

Lesson 1 Lesson 2 Lesson 3

Perpendicular lines Parallel lines Angles

134 138 142

Quadrilaterals and prisms

153

Lesson 1 Lesson 2 Lesson 3 Lesson 4

154 163 169 171

Properties of quadrilaterals Drawing quadrilaterals Angles in quadrilaterals Prisms

Perimeter and area of quadrilaterals

174

Lesson 1 Lesson 2 Lesson 3

175 178 184

Perimeter of a quadrilateral Area of a parallelogram and a rhombus Word problems

Bar graphs and line graphs

187

Lesson 1 Lesson 2

188 198

Bar graphs Line graphs

Computational thinking

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203

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The big idea

Illustrates a scenario through which students can connect to the chapter.

Chapter 8

Volume and capacity

Computational thinking

Special Features

Introduces a new approach for solving complex problems with confidence.

The edge of the cubes is 1 m long. How do we find the volume of each cube? Must we fill it with water to find its volume?

Lesson 1

Volume and capacity of a cuboid

Lesson 2

Volume of a liquid

Lesson 3

Word problems

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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

4 _ = ?% 4 _ 5 = ?% 5

Starting point

Can we change a fraction or a decimal into a percentage?

Learning to know

Breaking a complex problem into manageable, smaller problems

Lesson 3 Fractions and decimals as percentages

Learning to know

Algorithms

1.5 = ?% 1.5 = ?%

Developing a set of step-by-step solution

Fractions as percentages

Identifying similarities and differences, and observing similar patterns

Abstraction Focusing on relevant information, and removing irrelevant information

2 Convert 5 into a percentage.

Method 1: Convert it into its equivalent fraction with 100 as the denominator.

Introduces new concepts using the CPA approach with engaging illustrations.

Pattern recognition

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.

2 40 5 = 100

Computational thinking | 203

× 20

2 5

= 40%

=

40 100

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× 20

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Method 2: Multiplying the fraction with 100%.

2 2 5 = 5 × 100% 200 = 5 %

Fun with Maths!

= 40%

Thinking corner

Challenges students with unconventional questions to develop higher-order thinking skills.

Which method do you prefer? Why? 96 | Mathematics Prathomsuksa 5

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Allows students to explore mathematical concepts actively either as an individual or in groups.

1. Get into groups of five.

2. Get a few prisms and count the numbers of total faces (bases and lateral faces), vertices and edges of the prisms. Fill in the table. In the table, F stands for the number of total faces, V stands for the number of vertices and E stands for the number of edges.

Quadrilaterals

F

V

E

F+V

E+2

Triangular prism Square prism Cuboid Pentagonal prism Hexagonal prism 3. What do you infer from the last two columns? Are they the same? This relationship is known as Euler’s formula. It is applicable for any polyhedrons.

1. Name the parts of this prism.

Try this

2. Name these prisms.

Chapter 10 | 173

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Provides various exercises to immediately evaluate students’ understanding.

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Chapter 1

Addition and subtraction of fractions

How do you divide the two pizzas equally among the three of them?

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Lesson 1

Fractions and division

Lesson 2

Comparing and ordering fractions

Lesson 3

Addition and subtraction of fractions

Lesson 4

Word problems

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Lesson 1

Fractions and division

Starting point

There are two children. There is a pizza. How do we divide the pizza equally among the children? What fraction of a pizza will each child get?

Learning to know

Fractions as division

When 2 pizzas are divided equally between 2 children, each child gets 1 pizza.

2 2÷2= 2 =1

When 2 pizzas are divided equally among 3 children, each child gets 2 pizza.

3

2 2÷3= 3 2 1444442444443

We can use a bar model to represent it.

2 3

2 3

2 3

2 | Mathematics Prathomsuksa 5

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3 When 3 pizzas are divided equally among 4 children, each child gets 4 pizza.

3 14444444244444443

3 3÷4= 4

3 4

3 4

3 4

3 4

What fraction of a pizza does a child get when 3 similar pizzas are shared equally between 2 children?

3 3÷2= 2

3 144424443 3 2

3 2

1 = 12

or

1 2 3 – 2 1

3 1 Each child gets 2 or 1 2 of a pizza.

Express each as a fraction or a mixed number in its simplest form.

1. 3 ÷ 5 =

2. 9 ÷ 12 =

3. 16 ÷ 10 =

Chapter 1 | 3

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Lesson 2 Comparing and ordering fractions Starting point

1 3

Analyze the 3 fractions.

4 9

Which is the greatest? Which is the smallest?

How do you find out?

7 18

Comparing fractions

Learning to know

Which is greater, 1 or 3 ?

3 5 We cannot compare them directly because they have different denominators. We need to change them to fractions with the same denominator first.

×5

1 3

= ×5

×3

5 15

3 5

9 15

= ×3

Now, compare 5 and 9 .

15 15

5 15

9 15

9 is greater than 5 .

15 15 So, 3 is greater than 1 .

5 3 4 | Mathematics Prathomsuksa 5

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3 1 Which is smaller, 5 or 2 ? ×2

3 5

×5

6 10

=

1 2

×2

5 10

= ×5

6 10

5 10

5 is smaller than 6 .

10 10 So, 1 is smaller than 3 .

2 5 2 1 Which is greater, 1 3 or 1 2 ?

Since the whole numbers of both mixed numbers are the same, we need to compare only the fractional parts. ×2

2 3

=

×3

4 6

1 2

=

×2

×3

4 6

3 6

3 6

4 is greater than 3 .

6 6 So, 1 2 is greater than 1 1 .

3 2 Chapter 1 | 5

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1 5 Which is smaller, 3 4 or 1 7 ?

When comparing mixed numbers, compare the whole numbers first.

1 is smaller than 3.

5 1 So, 1 7 is smaller than 3 4 .

5 Which is greater, 2 6 or 14 ?

5 Method 1: Convert the mixed number into an improper fraction. ×6

×5

5 17 26 = 6

85 30

=

14 5

84 30

= ×6

×5

85 is greater than 84 .

30 30 5 So, 2 6 is greater than 14 .

5

Method 2: Convert the improper fraction into a mixed number. ×5

5 26

=

×6

25 2 30

14 4 5 =25

×5

=

24 2 30

×6

2 25 is greater than 2 24 .

30 30 5 So, 2 6 is greater than 14 .

5

Which method is easier for you? Why?

6 | Mathematics Prathomsuksa 5

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Which is smaller, 45 or 5 2 ?

8 3 Method 1: Convert the mixed number into an improper fraction. ×3

45 8

×8

2 17 53 = 3

135 24

=

=

×3

136 24

×8

135 is smaller than 136 .

24 24 So, 45 is smaller than 5 2 .

8 3 Method 2: Convert the improper fraction into a mixed number. ×3

45 5 = 5 8 8

×8

2 53

15 5 24

=

=

×3

16 5 24

×8

5 15 is smaller than 5 16 .

24 24 So, 45 is smaller than 5 2 .

8 3 Compare 11 and 15 .

8 11 × 11

11 8

=

×8

121 88

15 11

× 11

121 120 88 is greater than 88 .

So, 11 is greater than 15 .

8 11

=

120 88

×8

or

120 121 88 is smaller than 88 .

So, 15 is smaller than 11 .

11 8 Chapter 1 | 7

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