My Mathematics Book Grade -4 [English version] PDF Download CDC

 

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Table of Content

Unit Lesson Page

1. Geometry 1-11

1.1 Solid shapes 1

1.2 Face, edge and corner of solid 2

1.3 Angles 4

1.4 Measurement of angles 6

1.5 Construction of angles in the interval of 100 8

1.6 Angles less than and greater than 900 9

2 Concept of numbers 12-25

2.1 Origin of numbers 12

2.2 Number up to crore 15

2.3 Rounding off numbers 20

2.4 Prime and composite numbers 23

2.5 Prime factors 24

3 Basic operation in mathematics 26-42

3.1 Subtraction 26

3.2 Daily life problems related to subtraction 28

3.3 Multiplication 30

3.4 Daily life problems related to multiplication 32

3.5 Division 33

3.6 Daily life problem related to division 38

3.7 Simplification 39

4 Fraction, decimal, percentage and unitary method 43-69

4.1 Fraction 43

4.2 Decimal number 56

4.3 Percentage 67

4.4 Unitary method 69

5 Time, money and measurement 70-102

5.1 Day, week, month and year 70

5.2 Money 81

5.3 Distance 84

5.4 Perimeter of a rectangle 89

5.5 Area 91

5.6 Capacity 94

5.7 Volume 98

5.8 Weight 99

6 Bill and budget 103-104

7 Statistics 105-111

7.1 Bar graph 105

7.2 Reading a thermometer 108

7.3 Ordered pairs 109

8 Sets 112-115

8.1 Introduction 112

8.2 Methods of writing sets 114

9 Algebra 116-130

9.1 Variable and value 116

9.2 Algebraic terms and expressions 118

9.3 Like and unlike terms 119

9.4 Algebraic equation 125

My Mathematics, Grade 4 1

1.1Solid shapes

Some solid shapes, their mathematical names and physical models

are given in the following table. Could you add two more examples

in each row as given in the table?

Solid shapes Mathematical names Physical models

Cuboid (All surfaces

are rectangular)

Cube (All surfaces

are square)

Cylinder (Bases are circular

and surrounded

by curved surface)

Sphere (Round solid

shape)

1. Write the mathematical names for each of the following solid

objects.

(a) (b) (c)

1 Geometry

Exercise

2 My Mathematics, Grade 4

(d) (e) (f)

(g) (h)

1.2 Face, edge and corner of solid

C o u l d y o u t e l l w h i c h

geometrical shape is the chalk

box? Yes, it is an example of

cuboid. Cut the chalk box with

scissors along the edges and

open it as shown in the figure.

What do you find?

A cuboid has six rectangular

faces. For example: Chalk box

All faces of a cuboid are

rectangular. A cuboid has six

rectangular faces.

Net is a drawing which shows

all faces of a solid. We can

make solid objects by folding

nets.



Geometry

box

Net of cuboid

Ink

My Mathematics, Grade 4 3

We can make a chalk box again by

folding the previous six faces which

is cut above. Try it yourself.

Skeletal models of solids can be made

by using straws of wheat, pipes of cold

drinks, sticks, etc.

In the adjoining figure, figure of a

cuboid and skeletal model of that

cuboid are given. The skeletal model

is made by pipes. Such models made

by pipes, straws and sticks are called

the skeletal models.

How many pieces of pipes are used in the above skeletal model?

Each piece of pipe represents the edge of the solid.

In the above figure, three edges of the skeletal model meet at a

point. Such points are called vertices of the solid.

In the above cuboid, how many faces, edges and vertices are

there? Above activities help us to draw the following conclusion:

There are 6 faces, 12

edges and 8 vertices in a

cuboid.

1. Write the number of faces, edges and vertices of the following

solids.

(a) (b)

Surface

Solid object

Skeletal model

Edge Vertex

Exercise Surface

4 My Mathematics, Grade 4

Collect some solid objects found in your surrounding. Show each

object and tell their local and mathematical names. Draw a table

and write local and mathematical names. Ask the students to collect

solid objects and identify their mathematical names and classify.

Use practical method to teach faces, edges and vertices.

1.3 Angles

When we lift any object

with hand, our arms

make an angle.

Our legs make angles while walking.

Hands of a clock make different angles

at different time.

Similarly, can you give some more

examples of angles?

(c) (d)

Teaching Instructions:

My Mathematics, Grade 4 5

When the end of a line segment is kept fixed

and other end of line segment is rotated,

an angle is formed. In the adjoining figure,

point "O" of line segment "OA" is kept fixed

and point "A" is rotated, when it reaches at

point 'B', it makes an angle AOB. It is written

as ∠AOB. The angle can also be written as

∠BOA. But it cannot be written as ∠OBA

or ∠OAB, why? A model of angle can be

made by using two long strips of card board

as shown in the adjoining figure.

When two line segments intersect each

other, angles are formed. In the adjoining

figure, line segment AB and CD intersect

at point O, and ∠AOC is formed. There are

some more angles in the figure, can you

write names of angles?

2. The objects that can be used to make angles, and objects having

angles are given below. Write three such figures in your exercise book.

(a) (b)

Ask the students to use physical objects as the example of angles.

The example given here are symbolic only.

1. Write the names of the following angles in two ways:

(a) (b) (c) (d)

Exercise 1.3

Teaching Instructions:

6 My Mathematics, Grade 4

We use protractor to measure

angles. The unit of an angle is

measured in degree. Look at

the protractor carefully given

in the figure. There are two

scales in the protractor, inner

scale and outer scale. There

is 0° mark in inner scale and

180° mark in outer scale at the

same point. Similarly, there is

180° mark in inner scale and

1.4. Measurement of angles

What is the

measurement of this

angle ? How can you

find it?

baseline centre inner scale

outer scale

0° starts mark in outer scale at the same point. In the inner scale, 0°

from the right side and gradually increases up to 180° reaching left

side. Likewise, in the outer scale, 0° starts from left side and gradually

increases up to 180° reaching the right side. Two scales are in the

protractor to measure angles conveniently. Let’s study how to measure

an angle.

To measure ∠AOB

– Fix the protractor over

the angle keeping the

point O at the centre of

the protractor and OA

along the base line of the

protractor.

– The line segment OB

passes through 30° in the

inner scale. Therefore,

∠AOB is 30°.

My Mathematics, Grade 4 7

Similarly, to measure ∠PQR

– Fix the protractor over

the angle keeping the

point Q at the centre of

the protractor and QR

along the base line of the

protractor.

– The line segment PQ

passes through 40° in the

outer scale. Therefore,

∠PQR is 40°.

1. Measure the size of each of the following angles using protractor

and write in your exercise book.

(a) (b) (c)

(d) (e) (f)

2. Measure the size of internal angles of the following triangles:

(a) (b) (c)

Exercise 1.4

8 My Mathematics, Grade 4

3. Find the size of angles in the following figures.

(a) (b)

While teaching to measure size of angles, to boost the self confidence of the

students, draw the angles of different sizes on the board and ask them to measure

the size. Collect the objects which represent angles found in your surrounding,

and draw or ask them to draw figures of the objects. Then, ask them to measure

the size of the angles.

1.5Construction of angles in the interval of 10°.

Let's construct an angle of 30°.

- Take a point O in your exercise book.

- Draw a straight line segment OP.

- Place the protractor in such a way that

its centre is at point O and adjust base

line of the protractor along OP.

- Observe 30° on the inner scale and

mark a point Q against it.

I learnt to measure the

size of angle but I cannot

construct the angle of the

given size, what to do?

Don’t worry. It's

easier.

Teaching Instructions:

My Mathematics, Grade 4 9

- Remove the protractor and join

O and Q using a ruler.

- The POQ is the required angle of 30°.

- ∠POQ = 30°

1. Construct angles of the following sizes by using the protractor.

(a) 20° (b) 40° (c) 50° (d) 60° (e) 80°

(f) 90° (g) 110° (h) 120° (i) 140° (j) 150°

While teaching construction of angle, it will be better to demonstrate on the

board by using educational materials (protractor and ruler), and ask the students

to follow as classwork.

1.6Angles less than and greater than 90°

The figure alongside is the figure of set square.

One of the angles of the set square is 90°.

Construct 90° by using protractor.

Place a set square as shown in the figure.

Adjust 90° corner of the set square just

over point O of ∠AOB and edges of the set

square along the side of the arms of the angle.

An angle of 90° is called a right angle.

Right angle, angles greater or less than right

angle can be recognized by using a set square.

Teaching Instructions:

Exercise 1.5

Q

10 My Mathematics, Grade 4

In the adjoining figure, arm OB of

∠AOB lies within the set square

as the base line of the set square is

adjusted along the arm OA. In such

case, ∠AOB is less than 90°. An angle

of size lesser than 90° is called an

acute angle.

In the adjoining figure, arm OB of

∠AOB lies outside the set square

as the base line of the set square is

adjusted along the arm OA. In such

case, ∠AOB is greater than 90°. An

angle of size greater than 90° is called

an obtuse angle.

Some angle’s size may be of two right

angles. Such angles are called straight

angles. The size of a straight angle is

180°. In the adjoining figure, arms

OA and OB of ∠AOB lie along the

bases of set squares (two set squares).

Therefore, ∠AOB = 180°. ∠AOB is a

straight angle.

1. Estimate which of the following angles is right, acute, obtuse

or straight angle. Use a set square to check your answer.

(a) (b) (c)

Exercise 1.6

My Mathematics, Grade 4 11

(d) (e) (f)

2. Name all angles in each figure below and classify them into obtuse,

acute or right angles.

(a) (b)

3. Classify the angles formed by hands in each of the following

clocks into acute, right, obtuse and straight angle.

(a) (b) (c) (d)

Here, set squares are used to classify angles. Besides that protractor can

be used to measure angles. It will be appropriate to use paper cutting set

squares to classify angles into acute, right and obtuse angles. In order

to classify angles formed in objects found in the surrounding, ask the

students to collect such objects found in their surrounding.