Computer Science Grade 3

1|Computer Science class 3

Writer : Pramish Koirala
Shubham Pokharel

Editor : Pramish Koirala
Designer : Pramish Koirala
Language : Pramish Koirala
Computer : Pramish Koirala and Shubham Pokharel
© Writer

2|Computer Science class 3

Preface

This " Literacy Computer Science-3 " Series is based on "let's do
what we learn". This book is designed simply students friendly
and languages used here are very easy.
Salient features of this book

- Students friendly
- Great for beginners
- Easy and less
- Important full forms included
- Very effective exercises
- Every lesson has lab activity
- Pictorial representations
I would like to thank Mr. Shubham Pokharel for helping me
write some lesson. I would like to thank my sister Pramisha
Koirala for encouraging me to write computer science book
series. I would also thank my parents for this and thank you
for reading this book.

Pramish Koirala

3|Computer Science class 3

Table of Contents

1. Introduction to computer
2. Input/ Output devices
3. Some important full forms
4. Opening and closing MS- Paint
5. Opening and closing Computer

4|Computer Science class 3

1Pr

Introduction to computer

A computer is a man-made electronic machine. It works very fast
and accurately. It is very diligent machine. It is used everywhere. We
have the basic need of the computer. It is so good that it can work
faster than any human being.
1.1 Parts of a computer
Computer does many work not only with it but with the help of its
parts. Some of the parts of a computer are as described below.

1. Monitor : It is a screen of a computer.

2. CPU : It is the heart of a computer.

3. Keyboard : It is a typing device and is used to give instructions.

4. Mouse : It is a pointing device.

5. Printer : It is used to print documents.

6. Speaker : It helps in listening sounds.

5|Computer Science class 3

1.2 APPLICATION AREAS OF A COMPUTER
Computer has become very important part of human life. It helps
people complete their tasks easily and faster. It is almost impossible
to imagine the modern facilities without the use of computers. The
following are some most important areas of a computer.

1. Education Sector
Computers are used in educational sectors to teach students online
or visually. It is also used in educational sectors for preparing

results, admit cards, letters and many more things. It is even used by
teachers to teach students about computers and prepare materials.

2. Health and Medical sector
Computers are used in health and medical sectors to do critical
operations of the patients, make and distribute medicines, prepare
bills etc.

3. Financial sector
Computers are used in financial sectors to do calculations,
to keep records, for accounting and many more things.

4. Offices
Computers are used in offices to keep records of workers, their

salary,
records of income and expenditures etc.

5. Business
Computers are used in business for online buying and selling,
preparing bills, keeping records of customers etc.

6|Computer Science class 3

6. Entertainment Sector
Computers are used in entertainment sectors for editing or

recording serials, movies and edit them. They are also used there for
making cartoons using animations.

7. Home
Computers are often used at home for playing games, doing

homework's and assignments and many more things.

8. Transportation
Nowadays computers are even used to run a vehicle or fly an

aeroplane. Computer has become so much powerful that by using it
we can run a vehicle sitting in office or inside it.

9. Engineering
Computers are used in engineering for designing roads, cars,

monuments etc. using software's.

7|Computer Science class 3

1. Fill in the blanks:
a. ____ is a screen of a computer.
b. Computers are used in _____________ to teach students online
or visually.
c. Computers are used in financial sectors to do calculations,
to keep records, for______ and many more things.

2. Write T for true and F for false:
a. We cannot use computer in our home.
b. Computer can work itself.
c. A computer is not a man-made electronic machine.
d. Computer is so good that it can work faster than any human
being.

3. Answer the following questions:
a. Define a computer.
b. Enlist any four devices of a computer.
c. List any 8 areas where computers are used.
d. Why computer is used in engineering?

4. Draw a neat and clean figure of a computer system.

LAB ACTIVITY
Follow the given steps
- Open computer
- Press Window + R key using keyboard
- Type MS-Paint on run dialog box
- And enjoy

8|Computer Science class 3

2

Input and output devices

As we have read about computer in previous lesson, we are going to
read about parts of computers here. There are Four devices used in
a computer mainly. They are: -

1. Input devices
2. Processing devices
3. Output devices
4. Storage devices

But in this grade, we will only read about input and output devices.
2.1 Input devices

Think, you are eating an apple. That means you are giving input
from your mouth to stomach. Likewise, we need to give instructions
to the computer using some devices. Those devices are called input
devices.

Simply those devices which are used to give instructions to the

computer are called input devices. Some of the input devices are

listed below:

1. Keyboard 3. Mouse

2. Web cam 4. Joystick

9|Computer Science class 3

2.2 Output devices

The obtained result after processing is called output. But output is not

exactly a waste material like excreta in terms of compute science. It is

useful information obtained. So, you may define output devices as

devices showing or providing meaningful result after processing

are called as output devices. Some of the output devices are:

1. Monitor 2. Speaker

3. Printer

10 | C o m p u t e r S c i e n c e c l a s s 3

1. Fill in the blanks:
a. There are ______ devices used in a computer mainly.
b. Those devices which are used to give instructions to the computer
are called _______ devices.
c. The obtained result after ________is called output.

2. Write T for true and F for false:
a. Input devices gives us output.
b. Computer can work without input devices.
c. Mouse is a output device.
d. Eating an apple means giving input.

3. Answer the following questions:
a. Define input devices.
b. Enlist any four output devices of a computer.
c. List any 4 output devices.
d. What are the four main devices of a computer?

4. Draw any 1/1 input and output devices.

LAB ACTIVITY
Follow the given steps
- Open computer
- Press Window + R key using keyboard
- Type winword on run dialog box
- And write the list of input and output devices there.

11 | C o m p u t e r S c i e n c e c l a s s 3

3

Some important full forms

1. CPU – Central Processing Unit
2. MU – Memory Unit
3. CU – Central Unit
4. ALU – Arithmetic and Logical unit
5. ATM – Automated Teller Machine
6. RAM – Random Access memory
7. ROM – Read Only Memory
8. MS – Microsoft
9. PC- Personal Computer
10. OS – Operating System
11. CD – Compact Disk
12. TXT – Text
13. DVD – Digital Versatile Disk
14. DB – Database
15. CTRL – Control

12 | C o m p u t e r S c i e n c e c l a s s 3

4

Opening and closing MS- Paint

4.1 INTRODUCTION
Microsoft paint is a simple graphic program. You can draw, save and
edit drawing or pictures in ms-paint. Microsoft paint provides all the
necessary drawing tools to draw pictures, color pictures and modify
the existing drawings. The images, drawing created in ms-paint are
called computer graphics. So, a graphic created in a computer is called
computer graphic.

4.2 OPENING MICROSOFT PAINT
You need to open paint program to draw pictures. You need to use
mouse to draw pictures in ms-paint. You have to use left mouse
button for the most of the functions. To open paint program, follow the
following steps:
a. Click on the start button or start menu.
b. Click all programs or all apps.
c. Scroll the application list and click Accessories.
d. Click paint.
NOW YOU SEE THE PAINT WINDOW.

13 | C o m p u t e r S c i e n c e c l a s s 3

4.3 CLOSING MICROSOFT PAINT

When you finish your work in paint, you can close paint program. To
close the paint program, perform these following steps;

a. Click on the file menu/paint button. It displays sub menus.

b. Chose the exit command.

You can close paint simply by clicking on the close button on
the title bar, too.

4.4 Parts of paint windows

The paint window consists of title bar, Quick Access toolbar, file
tab, ribbon scroll bars, status bar and drawing Area.

14 | C o m p u t e r S c i e n c e c l a s s 3

1. True or false:
a.Ms-paint helps you to draw pictures and color them.____
b.Paint has many different drawing tools._____
c. The drawing area is the area where we can draw pictures.____
d.Paint has many different drawing tools._____
e. Eraser tool is use for erase the drawing.____

2. Fill in the blanks:
a.Each drawing tool has ________ use.
b.Color box are used for __________
c. Eraser tool is used for ___________

3. Answer the following questions:
a.What is Ms-paint?
b.What is the use of drawing area?
c. List few steps to save the drawing.
d.What is the use of eraser?
e. In how many ways we can open Ms-paint?

LAB ACTIVITY
Follow the given steps
- Open MS-Paint and Draw your school

15 | C o m p u t e r S c i e n c e c l a s s 3

5

Opening and closing Computer

Every computer must need to have operating system. The operating
system is the basic requirement of a computer. Without operating
system is the basic requirement of a computer. Without operating
system a computer cannot work. The operating system a computer
cannot work.
The operating system provides life to the computer it provides the
interface (that is the junction between a user and a computer
program) to communicate with a computer. It makes a computer
ready to do task. There are many operating systems. Microsoft
Windows XP, Windows 8, Windows 10 and Windows 7 are the
popular operating systems of Microsoft.
STARTING COMPUTER
When you have to use a computer, you need to start up the
computer. The starting up of a computer is called booting. You can
start WINDOWS 10/8/7 just by turning on the power button of a
computer. The computer takes few minutes to load the necessary
files of operating system on the computer. When the computer is
ready, it displays “log on” screen where you need to choose User and
enter password.

16 | C o m p u t e r S c i e n c e c l a s s 3

When you enter correct password, it displays the desktop where
you see a taskbar and icons.

SHUTTING DOWN THE COMPUTER
You need to shut down a computer properly. To shut down the
computer you need to follow these steps:

1. Click on start menu button it displays option.
2. Click on shut down button. In the case of windows 10, click

or power. It displays options. Choose shut down.

The computer turns off after a few seconds. You don’t need to
press power switch. But you need to turn off the monitor.

17 | C o m p u t e r S c i e n c e c l a s s 3

1. True or false
a)The computer turns off in few second. ____
b)Clicking on start button computer gets off. ____
c) You need to turns off computer properly. ____
d)We can shut down computer only in windows 10. ______

2. Fill in the blanks:
a. Computer gets off in ___________ second.
b. Clicking on start button computer gets __________.
c. Clicking on off button computer gets ________.

3. Answer it:
a. List the steps of computer to open it.
b.List the steps of computer to close it.
c. List any four operating systems.
d.What is start Up the computer?
e. What systems give life to the computer?

LAB ACTIVITY
Follow the given steps
- Open and shut down the computer.

18 | C o m p u t e r S c i e n c e c l a s s 3

MODEL QUESTION

1. Fill in the blanks: 6x1=6
a. __________ is a full screen of a computer.
b. Computers are used in _____________ to teach students online or

visually.
c. There are _________ device used in computer mainly.
d. Color box are used for ________.
e. Computer gets off in __________.
f. Clicking on start button computer gets_________.

2. True or false: 6x1=6
a. We cannot use computer in our home.___
b. Computer can work itself.___
c. Paint has many different drawing tools.___
d. Eraser tools is used for erasing the drawing____
e. Mouse is a output device._____
f. The computer turns off in few seconds._______

3. Answer it: 6x3=18
a. Define a computer.
b. Why computer is used in engineering?
c. Define input devices.
d. What are the four main devices of a computer?
e. What is MS-paint?
f. List few steps to save the drawings.

19 | C o m p u t e r S c i e n c e c l a s s 3

4. Answer these question in long :☺ (2x5=10)
a. List the steps to open the computer.
b. Draw a computer system.

5. Write the work of following devices: (5x1=5)
a. Mouse
b. Printer
c. Keyboard
d. Speaker
e. Monitor

6. Full forms: (5x1=5)
a. CD=
b. RAM=
c. CPU=
d. TXT=
e. OS=
50 marks for practical

20 | C o m p u t e r S c i e n c e c l a s s 3

21 | C o m p u t e r S c i e n c e c l a s s 3

22 | C o m p u t e r S c i e n c e c l a s s 3