Pelangi Primary Education Smart Mathematics P1 (New Edition)

Contents Chapter 1

Numbers 0 to 10................................................... 1 1 Numbers 0 to 10............................................................................... 2 2 Counting forward and backward..................................................... 4 3 Ordering the numbers...................................................................... 5 4 Comparing numbers........................................................................ 6

Chapter 2

Addition within 9................................................. 12 1 Meaning of addition..........................................................................13 2 Adding numbers............................................................................. 14 3 Adding 0.......................................................................................... 17 4 More about addition........................................................................ 18

Chapter 3

Subtraction within 9..............................................24 1 Meaning of subtraction.................................................................. 25 2 Subtraction of numbers................................................................. 26 3 Counting and subtracting.............................................................. 29 4 Subtraction with 0.......................................................................... 34 5 Subtraction and addition............................................................... 35

Chapter 4

Numbers up to 20.............................................. 39 1 Numbers 11 to 20........................................................................... 40 2 Tens and ones................................................................................ 41 3 Using the signs, = and â&#x2030; ............................................................... 43 4 Using the signs, > and <............................................................... 44 5 Ordering the numbers 11 to 20...................................................... 45

Chapter 5

Addition and Subtraction within 20............................52 1 Adding numbers............................................................................ 53 2 Adding up three 1-digit numbers.................................................. 57 3 Subtracting numbers..................................................................... 59

Chapter 6

Length.............................................................66 1 Words related to length................................................................. 67 2 Comparing and measuring lengths.............................................. 70 iii

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Chapter 7

Mass.............................................................. 76 1 Words related to mass.................................................................. 77 2 Comparing and measuring masses.............................................. 78

Chapter 8

Volume............................................................84 1 Words related to volume............................................................... 85 2 Comparing and measuring volumes............................................ 87

Chapter 9

Numbers up to 100.............................................. 92 1 Numbers from 21 to 100................................................................ 93 2 Digits............................................................................................... 94 3 Place values................................................................................... 95 4 Comparing numbers..................................................................... 96 5 Using the signs, =, â&#x2030; , > and <....................................................... 98 6 Ordering numbers........................................................................ 100 7 Counting forward and backward................................................. 101 8 Counting by twos.......................................................................... 102 9 Counting by fives.......................................................................... 103 10 Counting by tens........................................................................... 104 11 Naming positions.......................................................................... 106

Chapter 10

Addition and Subtraction within 100.......................... 111 1 Adding up two numbers............................................................... 112 2 Using addition to solve problems.................................................. 114 3 Subtracting.................................................................................... 116 4 Subtracting three 1-digit numbers................................................. 117 5 Using subtraction to solve problems............................................ 118

Chapter 11

Combined Operations.......................................... 121 1 Doing combined operations......................................................... 122

Chapter 12

Time.............................................................. 127 1 Times of the day........................................................................... 128 2 Days of the week.......................................................................... 129

Chapter 13

Two-Dimensional (2-D) Shapes............................... 133 1 Names of 2-D shapes................................................................... 134 2 Describing 2-D shapes................................................................. 136 3 Patterns......................................................................................... 137 iv

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Ch a p r te

3

Subtraction within 9

How many pieces of pizza are left?

mes Learning Outco In this chapter students learn to

â&#x20AC;˘ subtract cardinal numbers not exceeding 9, and 0, as well as be aware of validity of the answers

â&#x20AC;˘ analyse and find answers to problems of cardinal numbers not exceeding 9, and 0, as well as be aware of validity of the answers

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Mathematics Pratomsuksa 1 CHAPTER

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Subtraction within 9

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1 Meaning of subtraction

4 minus 1 equals 3.

5 minus 1 is equal to 4.

8 minus 1 is 7.

Minus means take away.

Subtraction within 9 CHAPTER

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2 Subtraction of numbers There are four on the leaves.

One

jumps into

the water.

Three

are left on the leaves now.

4 1

We write :

3

4 – 1 = 3

We read : Four minus one equals three .

This is the ‘minus’ sign.

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Mathematics Pratomsuksa 1 CHAPTER

3

This is the ‘equal’ sign.

Subtraction within 9

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You can also find the answer by : Using your fingers Two children get off the train.

There are five children on the train.

Three children are left on the train.

5 â&#x20AC;&#x201C; 2 = 3 Using cancellation

Using marbles

Using a line number 0 1 2 3 4 5 6 7 8 9 28

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Subtraction within 9

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3 Counting and subtracting The rabbit hops down 3 steps.

How many more steps does it have to hop down to reach the ground?

2

1

3

4

5

6

7

9

8

9

9–3= 6

3

6

8 – 5 = 3

8 5

0 1 2 3 4 5 6 7 8 9

7 – 2 =

7 2

0 1 2 3 4 5 6 7 8 9 Subtraction within 9 CHAPTER

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He gives 5 peanuts to a monkey.

Suwat has a packet of peanuts.

Then, there are 3 peanuts left in the packet.

How many peanuts are there in the packet in the beginning?

–5=3

3

5

Let us fill in the blanks.

– 4 = 3 6–

= 4

8–

= 2 – 2 = 7

Subtraction within 9 CHAPTER

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–1=5 8– 3

=1

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Let us solve some problems.

There are 6 cups on a table. 2 of the cups fall and break. How many cups are left on the table now?

6–2= 4 Answer :

cups are left on the table now.

Kan has 9 crayons. He uses up 7 of them. How many crayons are left with Kan now?

9–7= Answer :

crayons are left with Kan now.

Sanit has 8 goats. He sells off 3 of them. How many goats are left with Sanit now?

Answer :

goats are left with Sanit now .

Keywords

 difference 36

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 minus

Mathematics Pratomsuksa 1 CHAPTER

 subtract 3

 subtraction

Subtraction within 9

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A Count and subtract.

1.

–

=

–

=

–

=

–

=

2.

3.

4.

B Fill in the blanks correctly.

1. 5 – 1 =

2. 4 – 4 =

3. 9 – 2 =

4. 7 – 1 =

5. 8 – 5 =

6. 7 – 3 =

7. 6 – 4 =

8. 9 – 6 = Subtraction within 9 CHAPTER

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