science class -3- 2077 press

Activity: 3

Take some water in a jar and measure its volume. Pour the water into different
vessels like jug, bowl, glass, beaker, etc and observe the shape. Find the volume of
water. What shape of water do you observe? Do you find any change in the volume
of water?
Liquid takes the shape of the vessel. It does not have its own shape. But a liquid has
definite volume.

Activity: 4

Take a syringe and pull water in it. Close the noozle and try to push the piston. Can
you push it?

Scan for practical experiment

URl: csp.codes/c04e17

Gas

Gases are the substances which do not have fixed shape
and volume. Things like air, smoke, water vapour, etc which
have no shape and volume are the gases. In gas, molecules
are apart from each other and they are always moving. A gas

Blooming Science, Health and Physical Education Book 4 101

blows from one place to another. Gas spreads throughout the
whole space of a container. It can be compressed in a small
vessel. We can fill air in a ball or bicycle tyre after it inflates
also. Oxygen, nitrogen, hydrogen, carbon dioxide, ammonia,
etc are the substances found in gas state.

Arrangement of molecules
Activity: 5

Take two balloons of different shapes. Blow
air into both balloons with your mouth and
observe their shapes. Balloons get inflated
due to the air blown into them. The shape
of air inside the balloon is like the shape of
balloon.

Activity: 6

Take a syringe and pull its piston. Now,
push the piston by closing its noozle. Can
you compress the air ? Observe it.
Air is compressible. It has no fixed shape
and size. It can be filled in any container.

102 Blooming Science, Health and Physical Education Book 4

Activity: 7

Take some incense stick (Agarbatti). Burn these and
keep at one corner of a room. Go to another corner and
observe it by smelling. What can you observe?

The smell of incense stick can be detected in all parts of
the room. It shows gas spreads freely in the space.

Change of state

One state of matter can be changed into another state. A
solid can be changed into liquid and a liquid into gas. Similarly,
a gas is changed back into liquid and liquid into solid. One state
of matter can be changed into another by heating or cooling.
This is called change of state.

cooling cooling
heating heating

Solid Liquid

Gas

The process of changing solid into liquid on heating is
called melting.
The process of changing liquid into gas on heating is called
vapourisation.
The process of changing gas into liquid on cooling is called
condensation.
The process of changing liquid into solid on cooling is
called freezing.

Blooming Science, Health and Physical Education Book 4 103

Activity: 8
Change of state

Take some ice cubes from a refrigerator. Keep these in a beaker and heat gently. Ice
cubes change into water. Then heat the water further. Water starts boiling and water
vapour is produced.

Scan for practical experiment

URl: csp.codes/c04e21

Key words

Prick – to pierce with a sharp point, puncture
not flexible
Rigid – distented with air or gas
a projecting spout
Inflated – the perfume of smoke arising from such a
substance when burned
Nozzle –

Incense –

Main Points to Remember

 Any thing that has mass and occupies space is called matter.
 A matter is made by very small particles called molecules.
 Matters exist in three states. They are solid, liquid and gas.
 Solid has fixed volume and shape.
 A liquid has fixed volume but no definite shape. A liquid flows from a higher

level to a lower level.
 A gas has no fixed shape and volume. A gas flows in all direction.
 A solid changes into liquid and a liquid changes into gas on heating.
 A gas changes into liquid and liquid into solid on cooling.

104 Blooming Science, Health and Physical Education Book 4

Project work

Observe different substances that are being used in your
house. Write them under the proper headings in the
following table.

Solid Liquid Gas

Exercise

1. Fill in the blanks with suitable words.
a. A matter has .................. and occupies ..................
b. A matter is made from very small particles called .........
c. A stone has definite .................. and ..........................
d. Water has definite .................. but no definite ..................
e. Air is an example of ..................
f. A gas does not have definite .................. and ..................
g. On heating, a solid changes into ..................
h. On .................., a gas changes into liquid.

Blooming Science, Health and Physical Education Book 4 105

2. Write ‘True’ for correct sentences and ‘False’ for wrong ones.
a. A matter does not occupy space.
b. Volume is the total space occupied by the body.
c. Kerosene is a solid substance.
d. Liquids can flow from higher level to lower level.
e. A liquid is changed into solid on heating.
f. The molecules of solid are compactly packed.

4. Answer the following questions:
a. What is matter ? Give any four examples.
b. Write any two properties of matter.
c. What are solid substances? Give any four examples.
d. Write down any two properties of liquid.
e. Write down any two properties of gas.
f. Define the following terms.
i. Melting
ii. vapourization
iii. condensation iv. freezing

5. Differentiate the following in two points each:
a. Solid and liquid
b. Liquid and gas

6. Draw the diagrams to show the arrangement of molecules
in solid, liquid and gas.

106 Blooming Science, Health and Physical Education Book 4

Lesson Heat Energy

10

Learning outcomes Scan for practical experiment

At the end of this lesson, the students will be able to:
 introduce energy and mention various forms of energy.
 demonstrate the effects of heat on matter.
 explain the utility of heat energy in daily life.
 list the methods of energy saving.

URl: csp.codes/c04e14

Boost Up

1. What does food give us?
..............................................................................................
2. Mention any four uses of heat in our daily life.
........................................... ...........................................
........................................... ...........................................

Energy

We need energy to survive and to do different works. We
get energy from food. A man carry load. The oxen pull the
plough on field. Moving water can move pebbles and sand
from one place to another. Blowing wind and running water

Blooming Science, Health and Physical Education Book 4 107

can rotate the turbine to generate electricity. It shows that the
man, the oxen, the moving water and the blowing wind have
the capacity of doing work. The capacity of doing work is
called as energy. It is used when work is done. We feel hungry
after doing physical work because our energy is used while
doing work. We can not see energy like matter, but we can feel
different forms of energy.

Energy exists in different forms. The main forms of energy
are as follow:

i. Heat energy ii. Light energy

iii. Electrical energy iv. Magnetic energy

v. Sound energy vi. Chemical energy

vii. Mechanical energy and viii. Nuclear energy

Heat as a source of energy

We like to sit in the sun during winter season as we feel
warm because we get heat from the sun. Similarly, we get
heat from burning fuel, coal, fire wood, electric heater, etc. We
feel warm from above mentioned sources. Heat is the form of
energy which gives the sensation of warmth. The sun is the
main source of heat energy for the earth. We get heat energy
from other sources like fire wood, electric heater, fuels, dry
dung, etc. We get heat from the food which burns with oxygen
in our body and gives us energy. We can perform various works
by using heat energy.

Effects of heat

Heat is a form of energy. We use heat energy for various

108 Blooming Science, Health and Physical Education Book 4

purposes like to cook food, to dry clothes and grains, to keep
the body warm, to run vehicles and industries, etc. Heat energy
affects substances in various ways. The volume of a body
increases on heating and decreases on cooling. Heat increases
the temperature of a body and heat can change the state of a
matter. Some of the important effects of heat energy are given
below:

i. Heat energy changes the volume of an object

ii. Heat energy changes the temperature of an object.

iii. Heat energy changes the state of a matter.

i. Heat energy changes the volume of an object

When a matter is heated, molecules of the matter moves
away from each other. The volume of matter increases, which
is called expansion of a matter due to heat. So, heat causes
expansion of a matter.
Activity: 1
Heat causes expansion in solid.

Suspend a metal sphere with the help of
a thin copper wire in such a way that the
gap between the sphere and the surface is
very less. Heat the wire with the help of a
burning candle and observe.
The metal ball will touch the surface. Why does this happen? Why does the size of
wire increase? Write down by discussing with your friends.

Scan for practical experiment

URl: csp.codes/c04e15

Blooming Science, Health and Physical Education Book 4 109

Activity: 2
Heat causes expansion in liquid

Take a round bottom flask filled with water level
coloured water. Fit a glass tube in its round
mouth with the help of a cork. Mark a
line to show the level of water in glass bottom flask
tube. Keep the flask into a hot water
tub. Observe after some time. What hot water
can you observe?

You will find water level risen up in the glass tube. Why does this happen ? Discuss
with your friends and write down the conclusion.

Activity: 3

Heat causes expansion in gas

Take an empty plastic bottle (small) with
a balloon fitted at its mouth. Keep it into
a hot water tub. Observe what change
do you see in the balloon? Why does this
happen? Discuss with your friends and
write down your conclusion.

ii. Heat energy changes the temperature of on object.

We can feel the hotness or coldness of an object by

touching it. It is the temperature that shows how hot or how

cold the object is. The degree of

hotness or coldness of a body is

called temperature. Temperature

of a body is measured by using

thermometers. When a body is

heated, its temperature increases. Thermometer

110 Blooming Science, Health and Physical Education Book 4

Activity: 4
Heat causes increase in temperature

Take some water in a beaker. Measure its cold water
temperature by using a thermometer.
Heat the water for about five minutes and hot water
again measure the temperature. What
difference can you find in the temperature
of water? Now leave the water to be cooled
and again measure the temperature. What
can you observe? Discuss with your
friends and write down the conclusion.

iii. Heat energy changes the state of a matter
There are three states of a matter. They are solid, liquid and
gas. Heat can change the state of a matter. A solid is changed
into liquid on heating and liquid is changed into gas. On
cooling a gas, it is changed into liquid and liquid is changed
into solid. For example, on heating ice (solid), it changes into
water (liquid) and on heating water, it changes into water
vapour (gas). On cooling water vapour, it changes into water
and on cooling water, it changes into ice.

heating heating

Solid Liquid

Scan for practical experiment Gas

URl: csp.codes/c04e18

Blooming Science, Health and Physical Education Book 4 111

Uses of heat Scan for practical experiment

Heat is very important for living beings. URl: csp.codes/c04e19
Living beings can not survive without heat.
Some important uses of heat energy are given
below:

a. Cooking food

Heat energy is required for cooking our food. We use
firewood, gas stove, kerosene stove, electric heater, etc
in our homes to cook food. Heat energy is obtained by
burning fire wood, LPG, kerosene, dry dung, etc

b. To keep ourselves warm

All animals and plants need heat energy to survive. They
need heat energy to make their body warm. We get heat
energy from the sun. We can also get heat energy from
electricity, fire wood, fuels, etc.

112 Blooming Science, Health and Physical Education Book 4

c. To run vehicles
Heat energy is required to run vehicles. Vehicles use disel,

petrol, gas, coal, etc to produce heat energy. Heat energy
is produced by burning fuels inside the engine of the
vehicles and then the vehicles can operate.

d. Drying of clothes and grains
Heat energy is required to dry wet clothes after washing.

It is also used to dry the grains before storing. The clothes
and grains are dried by keeping them in the sun.

e. To run factories
Heat energy is required to run machines in industries.

Heat is obtained when the fuels like coal and diesel burns.
Similarly, heat energy can be obtained from electricity to
run the factories.

Blooming Science, Health and Physical Education Book 4 113

Conservation of energy

We need energy in our daily life for various purposes. We
get energy from sources like coal, diesel, petrol, kerosene, fire
wood, bio gas, solar panel, etc. Some of the energy sources like
diesel, petrol, kerosene, coal, LPG, etc are non renewable
sources of energy. There is limited stock of such energy sources
on the earth. Some of the energy sources like solar energy,
biogas, hydro electricity are renewable sources of energy. We
should promote renewable sources of energy so that we can
use the fuels for a longer time in the future. We have to use
these sources wisely and save them for the future use. Some of
the methods that can be applied for the conservation of energy
are given below.

1. As far as possible, we have to use Scan for practical experiment
renewable sources of energy like solar
energy, wind energy, hydroelectricity and
biogas.

2. Fire wood, coal, petroleum, LPG, etc should URl: csp.codes/c04e20
not be overused.

3. It is better to use pressure cooker to cook food because
food gets cooked faster in a pressure cooker.

114 Blooming Science, Health and Physical Education Book 4

4. We have to use CFL or LED bulb instead of general bulbs.
When there is no use of electrical devices, we have to
switch them off.

5. We should protect our body by wearing warm clothes in
winter instead of using heater to get warmth.

6. We should plant trees for future use.

7. We should use public vehicles as far as possible.

Key words

Expansion – the increase in size (volume)

Thermometer – instrument used to measure temperature

LPG – Liquefied Petroleum Gas

Renewable energy – energy obtained from renewable resources
that can be reused

Nonrenewable – energy obtained from non-renewable
resources / cannot be reused

CFL – Compact Florescent Lamp

LED – Light Emitting Diode

Blooming Science, Health and Physical Education Book 4 115

Main Points to Remember

 Energy is the capacity of doing work. We need energy to do various types of
work.

 There are different forms of energy which are used for various purposes.
 Heat is a form of energy which gives the sensation of warmth.
 Heat can change the volume, temperature and state of an object.
 Heat is used for cooking food, making body warm, drying clothes and grains,

running vehicles and operating factories.
 We obtain energy from nonrenewable and renewable sources.
 We should use renewable sources of energy as far as possible.
 We should apply various methods for conservation of energy.

Project work

Make a list of energy sources used in your house and
write down their use.

S. No Energy sources Uses

116 Blooming Science, Health and Physical Education Book 4

Exercise

1. Fill in the blanks with suitable words.
a. .................... is the capacity of doing work.
b. Biogas is a .................... source of energy.
c. Heat gives the sensation of ....................
d. .................... is measured by using thermometer.
e. A solid changes into .................... on ....................

2. Write ‘True’ for correct sentences and ‘False’ for wrong
ones.
a. Heat is a source of energy.
b. The volume of copper wire increase on heating.
c. The volume of gas does not increase due to heat.
d. We use heat for drying clothes.
e. We should use LPG as much as we can.
f. The molecules of solid are compactly packed.

3. Describe an activity to show that volume of a solid increases
on heating.

(Write your answer on the basis of following points: Aim,
materials needed, method, observation, conclusion and diagrams)

Blooming Science, Health and Physical Education Book 4 117

4. Answer the following questions:
a. What is energy? What is the use of energy in our body?
b. What is heat energy?
c. Write down any three effects of heat.
d. Write down any four uses of heat energy in our daily
life.
e. What is temperature ? Which instrument is used to
measure the temperature?
f. Write down any two renewable and two non-renewable
sources of energy.
g. Make a list of any four methods that can be used to
conserve energy.
h. Draw a diagram of a thermometer.

118 Blooming Science, Health and Physical Education Book 4

Lesson

11 Weather and Seasons

Learning outcomes

At the end of this lesson, the students will be able to:
 introduce weather and describe its types in brief.
 introduce different types of seasons.

 explain various types of seasons with their characteristics.

Boost Up Summer
Winter
Match the following. Difficult to walk outside
Needs umbrella
Cloudy day Hot
Sunny day Cold
Rainy day
Windy day
Shorter day
Longer day

Blooming Science, Health and Physical Education Book 4 119

Weather

We can observe various changes in nature. We feel cold
at night and early in the morning. But it becomes warmer when
the sun shines. It changes at different moments during the day
also. Sometimes, it is sunny, sometimes it is cloudy and rainy.
Some days may be warm while the other days may be cold.Aday
may be windy or may be humid. The atmosphere may change
day to day and even from hour to hour also. The condition of
the atmosphere at a certain place during a particular period of
time is called as weather. The weather does not remain fixed.
It changes from time to time. It is because of the fact that the
weather is affected by different factors. The main factor that
causes change in the weather is the sun. Similarly, other factors
like wind, cloud, rain, humidity, etc also change the weather of
a place. The heat of the sun causes the wind to blow and clouds
to form. During sunny day, it is warm but the night is colder as
there is no heat of the sun. As the sun rays fall slanting in the
morning and evening, it is cold; but the sun rays fall straight in
the afternoon, so it is warm. In this way, the weather changes
from place to place and time to time.

The branch of science that deals with the study of weather
is called meteorology. The scientists who study weather are
called meteorologists.

Types of Weather Scan for practical experiment

i. Sunny day ii. Cloudy day URl: csp.codes/c04e22
iii. Rainy day iv. Snow fall
v. Windy day

120 Blooming Science, Health and Physical Education Book 4

The weather of a place depends on the factors like sun,
cloud, rain and wind. Weather can change within a very short
interval of time. Depending on the condition of various factors,
the weather of a place can be sunny, cloudy, rainy or windy.

Sunny day

When there is no cloud in the
sky, the sun shines very brightly.
The sky is clear and we feel warm
in such a day. During winter, sunny
days are not very hot. We feel
comfortable during these days. But
bright sunny days in the summer
are very hot.

Cloudy day

There are clouds in the sky and
the sun is blocked on cloudy days.
Cloudy days in winter are very
cold where as we feel cloudy days
pleasant in hot summer. Cloudy
days are comparatively dark and
colder. The clouds stop the loss of
heat from the atmosphere. So, cloudy nights are warmer than
clear nights. Basically in sunny days, due to heat of the sun
water present on the earth evaporates and reaches into the
cold atmosphere. Then it changes into small droplets of water
and cloud is formed. So, there are chances of rainfall if there is
cloud in the sky. But every cloud does not bring rain fall.

Blooming Science, Health and Physical Education Book 4 121

Rainy day

In a rainy day, there is rainfall from the sky. When water
vapour present in the atmosphere is cooled and condensed,
rainfall occurs. It rains mostly in the monsoon season in
our country. Regular and moderate rainfall is good to us.
The plants get water after rainfall. But heavy rainfall causes
several damages. It makes us difficult to walk in rain as the
roads become slippery after rainfall. Heavy rainfall may invite
various natural disasters like flood and land slide as well.

When the clouds reach higher altitude, the small droplets
of water freeze and change into hailstone. The hailstones are
heavier and start falling on the surface of the earth along with
the rain. It may destroy the crops, vegetables and fruits.

Sometimes, when the temperature of cloud suddenly falls
below 0°C, the water vapour changes into a solid mass and
snow is formed. The snowfall usually looks like small pieces of
cotton continuously falling down. The snow usually falls in the
mountainous region because the temperature of atmosphere
above the mountains is very low.

122 Blooming Science, Health and Physical Education Book 4

Windy day

The wind also brings changes
in the weather of a day. The blowing
air is called wind. The cold air that
moves gently is called breeze. It
is pleasant to us especially during
summer days. The fast moving air is
called storm. A storm is dangerous
to us. It may uproot the trees, blow
off the roof of the houses, break
down the electric poles and cause many other destructions. It
is difficult to walk outside in storm.

Seasons

We grow different types of crops in different months.
Some crops need more water and temperature and some
crops need less water and temperature. So, different plants
are cultivated and harvested in different times of the year. For
example, paddy is planted in the month of asar/shrawan and
harvested in kartik/mangsir. Similarly, wheat is planted in
mangsir/poush and harvested in falgun/chaitra. It is because
the weather of a place changes throughout a year. Similar type
of weather is found for few months in a year which is called
season. Season is the condition of the weather, comparatively
same for a longer period of time. There are four seasons in a
year. They are spring, summer, autumn and winter.

Change in season

The revolution, rotation and tilted axis of the earth are the
main causes of change in season on the earth.

Blooming Science, Health and Physical Education Book 4 123

The earth completes one revolution
around the sun in 365 ¼ days or one
year in its orbit. The revolution causes
the change in seasons. The earth
completes one rotation in its axis in 24
hours which makes a day. The half part
of the earth that is facing towards the
sun has day and the other half has night.
The position of the axis of the earth also leads to the change of
seasons. The axis of the earth is tilted at an angle of 66.5°. The
earth is divided into two equal halves by an imaginary line
called as equator. The northern hemisphere lies above the
equator and the southern hemisphere lies below the equator.
When the northern hemisphere is tilted towards the sun, the
southern hemisphere is away from the sun. Similarly, when
southern hemisphere is tilted towards the sun, the northern
hemisphere is away from the sun.

When earth
is revolving around
the sun in its circular
orbit with tilted
axis, sometimes the
sun rays fall straight
on the earth and
sometimes the sun
rays fall slanting
on the earth. When
sunlight falls straight in a place, it is more hot. In this way,
seasons are changed on the earth. So, different seasons are
observed in northern hemisphere and southern hemisphere.
Our country Nepal lies in northern hemisphere and here we will
be discussing about different seasons in northern hemisphere.

124 Blooming Science, Health and Physical Education Book 4

Types of season

There are four seasons in a year. They are summer, autumn,
winter and spring.

1. Summer

The summer season is the hottest
season of the year. It lasts from June to
August i.e. in the month of Jestha, Asar
and Shrawan. The north pole of the earth
is tilted towards the sun and northern
hemisphere gets direct rays of the sun
for longer time. In this season, the days
are longer and nights are shorter and
the sky is clear. The longest day in northern hemisphere is on
21st June.

2. Autumn

In autumn season, the temperature
is neither too hot nor too cold. It lasts
from September to November i.e. in
the month of Bhadra, Asoj and Kartik.
In this season, trees shed their leaves,
new leaves and buds grow and flowers
appear in some plant. The day and night
have equal duration in 23rd September.

Blooming Science, Health and Physical Education Book 4 125

3. Winter

Winter season is the coldest season
of the year. It lasts from December to
February i.e. in the month of Mangsir,
Poush and Magh. In this season, the
northern hemisphere gets the slanting
rays of the sun for a short time. The days
are shorter and the nights are longer. The leaves fall down from
trees and there is snowfall in the mountainous region. The shortest
day in northern hemisphere is 22nd December.

4. Spring

Spring is the most beautiful season
of the year. It comes after winter and
before summer. It lasts from March
to May i.e. in the month of Falgun,
Chaitra and Baisakh. In this season, the
temperature of environment remains
moderate. New leaves grow and flowers bloom on the plant.
The day and night have equal duration in 21st March.

Key words

Humidity – amount of water vapour present in air
Slanting – directed in a sloping or oblique direction
Pleasant – giving a sense of happiness, satisfaction
Harvest – the process or period of gathering in crops
Tilt – a sloping position
Moderate – average in intensity or degree
Bloom – produce flower, be in flower

126 Blooming Science, Health and Physical Education Book 4

Main Points to Remember

 The condition of atmosphere at a certain place during a particular period of time
is called weather.

 The weather keeps on changing.
 The weather of a place can be sunny, cloudy, rainy and windy.
 There are four seasons in a year: summer, autumn, winter and spring.
 The causes of change of season are revolution of the earth in its orbit and tilting

of the earth’s rotating axis towards or away from the sun.
 Summer is the hottest season of the year. It also rains during summer.
 The temperature of autumn season is moderate. Plants begin to shed their leaves

and coldness begins.
 Winter is the coldest season of the year. There is heavy snow in the regions away

from equator and in mountainous regions.
 Spring is the most beautiful season. The temperature remains moderate, plants

begin to grow and flowers bloom.

Project work

1. Study the change of seasons with the help of a globe and
lamp. Use lamp as sun and globe as earth. Keep the earth
in various positions and observe the position of northern
and southern hemisphere. Also locate the position of
Nepal on the earth in globe. Draw the diagram to show
the season change

Blooming Science, Health and Physical Education Book 4 127

2. Observe the weather of your school/home for seven days

and keep the record as shown in the given table.

Date Time Type of weather

2074/08/12 11:30am Sunny

Exercise

1. Fill in the blanks with suitable words.
a. The .................... does not remain same at a place for all
the time.
b. The .................... day of winter season is pleasant to us.
c. Flood may occur in .................... day.
d. The movement of the earth around the sun in its orbit
is called ....................
e. The seasons are changed due to the .................... axis of
the earth.
f. The flowers bloom in .................... season.

128 Blooming Science, Health and Physical Education Book 4

2. Write ‘True’ for correct sentences and ‘False’ for wrong
ones.

a. The weather varies according to the places.

b. The cloud does not contain water vapour.

c. Hailstones are formed when water vapour
condense suddenly..

d. The longest day of northem hemisphere is
21st march.

e. Tree leaves become yellow and start to shed in
autumn season.

f. Spring season is a very hot season.

3. Match the following:

Summer Falgun - Baisakh

Autumn Mangir - Magh

Winter Jestha - Shrawan

Spring Bhadra-Kartik

4. Mention the day.
a. Longest day in the northern hemisphere.
b. Day and night equal in spring.
c. Longest night in the northern hemisphere.
d. Shortest day in the southern hemisphere

Blooming Science, Health and Physical Education Book 4 129

5. Answer the following questions:
a. What is weather? Name different types of weather.
b. Make a list of different factors affecting weather.
c. Why are the cloudy nights warmer than clear nights?
d. How does snowfall occur in mountainous region?
e. What is season? What are the causes of change in
season?
f. Are the days and nights equal in all seasons? Why?
g. Which is the coldest season of the year? Why?
h. Which is the most pleasant season of the year? Why?

6. Draw the diagrams to show the change of seasons on the
earth.

130 Blooming Science, Health and Physical Education Book 4

Lesson The Earth in the
Universe
12

Learning outcomes

At the end of this lesson, the students will be able to:
 introduce solar system.
 differentiate planets and stars.
 introduce lithosphere, hydrosphere and atmosphere.
 explain various components of different layers of the earth.

Boost Up Surrounds the earth’s surface

Match the following:

Lithosphere

Hydrosphere Twinkling in the sky

Atmosphere Moving Around The Sun

Stars Covers ¾th Of The Earth’s Surface

Planets Covers ¼th Of The Earth’s Surface

Blooming Science, Health and Physical Education Book 4 131

There are infinte
things including space in
the universe. The universe
is all of the space and
time and its contents. It
includes planets, stars,
satellites, galaxies and all
matters and energy. The
size of the entire universe is still unknown, we are talking about
the observable universe only. We can observe only negligible
part of the universe. In this part, we can see many things in
the space like the sun, the moon, stars, some planets, shooting
stars, etc.

The solar system Scan for practical experiment

The sun along with the planets, satellites URl: csp.codes/c04e23
and other heavenly bodies that are moving
around the sun is called the solar system. It is
a group of heavenly bodies that are affected
by the gravitational force of the sun. The solar
system contains the sun, the planets, satellites,
asteroids, meteors, meteorites and comets.

The solar system

132 Blooming Science, Health and Physical Education Book 4

The Sun

The sun is a very hot ball of gases.
It is a star. It is the nearest star from the
earth. It is the only star which is visible
at day. Due to the very bright light of the
sun, other stars are not seen during day. It
is about 150 million kilometres away from
the earth. It is a main member of the solar
system around which all other heavenly bodies like planets,
asteroids and comets are revolving.

Satellites

The heavenly bodies that revolve around the planets are
called satellites. The moon is the only natural satellite of the
earth. All the planets of solar system have satellites except the
mercury and venus.

The moon

The moon is the natural satellite of the
earth. It is the brightest object that appears
at night. The moon does not have its own
light. It shines by reflecting the sunlight
that falls on it. It is about one fourth of the
size of the earth.

Asteroids

Asteroids are the minor heavenly bodies revolving around
the sun in between the orbit of inner and outer planets. All

Blooming Science, Health and Physical Education Book 4 133

the asteroids are revolving in their orbit between the orbit
of mars and Jupiter. They are many in number but small in
size. Asteroids range in size from tiny pebbles to about 930
kilometres in diameter.

Comet

Comets are heavenly bodies of
the solar system made up of gases,
dust and ice. They revolve around
the sun in very long elliptical orbits.
When a comet is passing close to the
sun, it gets warm and release gases
which is seen as a tail. So, the tail of
a comet is seen when it approaches
the sun. Halley’s comet, Benet, Enke, etc are some examples of
comet.

Stars

When we observe the sky at
night, we can see many twinkling
objects. They are the stars. Stars are
the huge balls of very hot gases.
They give off their own heat and
light. There are innumerable stars
in the universe.

The stars vary in size. Some of the stars that we see in the
sky are thousands of time larger than the sun whereas some
are smaller than the sun. The stars are seen very small in the
sky as they are very far from us. The sun is the medium sized
star which lies nearest to the earth.

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The Earth

The earth is the third planet of the solar
system from the sun. It is believed that the
earth was originated about 4500 million
years ago. During the origin of the earth,
there were no living beings. Life started on
the earth after a very long time of its origin.
Among eight planets, only the earth has suitable conditions for
life. The part of the earth which we can see appears almost flat
to us. But it is not flat in shape, it is seen flat as we can only see
a very small part of the earth. The earth is spherical in shape.
But it is not perfectly spherical. It is like an orange i.e. flattened
at poles and bulged out at the equator. The diameter of the
equator is slightly more than the diameter of poles. The
diameter of the earth at the equator is 12,756 km and that at the
poles is 12,713 km.

The earth has two types of
motion. It is moving around the
sun in its elliptical orbit. The
motion of the earth around the sun
is called revolution. It completes
one revolution around the sun
in 365 days and 6 hours or 365¼
days. Similarly, it spins in its axis.
The motion of the earth in its axis
is called rotation. It completes
one rotation in 23 hours and 56
minutes (24 hours) which is called as a day. The axis of the
earth is not straight. It is slightly tilted at an angle of 66.5°.
Because of the revolution and rotation of the earth in tilted
axis, the seasons and duration of day and night are changed
on the earth.

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Parts of the earth

The outer surface of the earth is made by land, water and air.
The earth has air at its outer surface. The three components of
earth are named as lithosphere, hydrosphere and atmosphere.
A short description of these three layers are given below.

Lithosphere

The land part of the earth is called lithosphere. Only one
fourth of the earth’s surface is land. Human beings and many
other animals and plants live on the lithosphere. The surface of
the lithosphere is not uniform and smooth throughout the earth.
On the basis of the surface of the lithosphere, it is divided into
plain, hills, mountains, plateau, valley, etc. The flat land of the
earth is called plain. There are plains close to sea level. Plains
are rich in fertile land and a part of it is made by desert also. The
Terai region of our country is a plain. Hills and mountains are
the raised part of the earth. The high summit of mountains are
the Himalays which are always covered by snow. The highest
peak of the world Mt. Everest (sagarmatha) lies in our country.
Plateaus are table - like plains on a height. Pamir of Tibet is an
example of a plateau. A valley is the plain surface surrounded
by hills. For example; Kathmandu, Pokhara, Dang, Surkhet,
Arun, etc are the valleys of our country. The valleys contain
fertile soil and are suitable for agriculture.

136 Blooming Science, Health and Physical Education Book 4

Hydrosphere

The part of the earth’s surface covered by water is called
hydrosphere. About three fourths of the earth’s surface is made
by hydrosphere. Water is found in different forms on the earth.
It is found in solid form in polar region and in the himalays. It is
found in liquid form in general and is found in the form of water
vapour in the atmosphere. In this way, there are various forms of
water like water (liquid), snow, water vapour, etc. Among these
various forms, water vapour and snow are the sources of water
over the earth’s surface. Water found in various sources like ocean,
river, pond, lake, etc are the sources of water on the surface of the
earth. Water is also found under the surface of the earth. This is
called underground water. The water coming out from spring,
well, etc are underground water. Hydrosphere is very important
for us. Water of various resources on evaporating by the heat of
the sun, form clouds and clouds form the rain. Water provides
shelter to many animals and plants. It is believed that the first life
was originated in water.

Pond Lake Glacier lake

Ocean Tube well River
Various sources of water

Blooming Science, Health and Physical Education Book 4 137

Atmosphere

The layer of the
air that surrounds
the earth’s surface is
called atmosphere.
Atmospheric air is
made by different
gases, water vapour,
smoke, dust particles, etc. The major gases found in the
atmosphere are nitrogen, oxygen, carbon dioxide and some
other inert gases. The atmosphere extends up to the height of
about 720 km from the earth’s surface. But about 99% percent
of air is found in the lowermost layer i.e. up to about 30 km
above the earth’s surface. The atmosphere makes it possible for
living organisms to survive on the earth.

Inside the earth

Internally, the earth is made by three different layers. They
are crust, mantle and core.

The outermost layer of the earth is
made up of soil, hard rocks and covered
with water in most places. It is called the
crust. This layer has a thickness of about
5 to 30 km.

Inside the crust, there is a hot layer
called mantle. This layer is very hot and
consists of rocks in molten state called
magma. The liquid rocks sometime
come to the surface during volcanic
eruption.

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The innermost layer of the earth is called core. It has two
parts, outer core and inner core. About 2200 km thick very hot
outer core lies below the mantle. In this layer, the heavy rocks
and metals are found in molten state. Inside this, there is a 1300
km thick innermost layer called inner core. The temperature
and pressure of this layer is so high that materials are found in
solid state.

Key words

Galaxy – group of millions of stars.

Gravitational force – A force that attracts any objects with mass.

Pebbles – a small rounded stone.

Bulged – a rounded projection or protruding part.

Main Points to Remember

 The universe is all of space and time and its contents.

 The group of sun, eight planets, satellites, comets and asteriods revolving around
the sun makes a family called the solar system.

 The sun is the nearest star from the earth and a main member of the solar system.

 The earth is the only living planet of the solar system.

 The earth’s surface is made by three layers. They are; lithosphere - the part of the
land, hydrosphere - the part of water and atmosphere - air that surrounds the
earth.

 The earth’s inside is made by three layers. They are crust, mantle and core.

Project work

1. Draw a diagram of solar system in your project copy.
Show it to your teacher.

2. Make a model of earth to show its internal structure by
using clay. Show it to your teacher in the class room.

Blooming Science, Health and Physical Education Book 4 139

Exercise

1. Fill in the blanks with suitable words.
a. There are ....................... planets in solar system.
b. ....................... is the largest planet.
c. The sun is the nearest ....................... from the earth.
d. The ....................... is the only living planet of the solar
system.
e. The earth completes one revolution in .......................
days.
f. The layer of air that surrounds the earth is called
.......................

2. Write ‘True’ for correct sentences and ‘False’ for wrong
ones.

a. Stars are the very huge of ball of gases..

b. The asteroids are very big in size.

c. All the planets have their satellites.

d. Lithosphere covers about one-fourth of the
earth’s surface.

e. Very hot magma is found in the crust..

f. The innermost layer of the earth is called as core.

140 Blooming Science, Health and Physical Education Book 4

3. Match the following: Nearest planet from the sun
Sun Largest planet
Farthest planet from the sun
Moon A medium sized star
Earth Natural satellite of the earth
Mercury Only living planet
Jupiter
Neptune

4. Answer the following questions:

a. What is solar system? Write down the name of eight
planets of solar system.

b. What are asteroids ? Where are they found?

c. When is the tail seen in comet?

d. What is hydrosphere?

e. Write down any three points of difference between
planets and stars.

f. What is lithosphere? Is it the same every where?

g. How is life possible only on the earth?

h. What are satellites? Write down the name of earth’s
satellite.

5. Draw the diagram of solar system and label all planets in
it.

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Lesson Information and
Communication
13
Technology

Learning outcomes

At the end of this lesson, the students will be able to:
 tell the importance of information.
 introduce and tell the characteristic of some means of information like letters,

radio, telephone, computer network, etc.
 introduce one way and two way communication with some examples.

Scan for practical experiment

Boost Up URl: csp.codes/c04e24

What informations do we get from the followings:

We are the social beings. We can not survive independently
in our society. We need to share our knowledge to others
and we need to gather some ideas from others as well. We
need to send and receive various messages to each other in
many different forms. The message distributed by a source
to one or many people is called information. We can pass the
information to each other by many ways. It can be verbal or

142 Blooming Science, Health and Physical Education Book 4

non-verbal. It can use some signs or symbols also. We are
using many sources of information around us. The newspaper,
libraries, magazines, hoarding boards, books, internet, letters,
etc are used as the sources of information. All the sources of
information mentioned above are non- verbal. Similarly, we
can get the information by radio, television and telephone also.
These sources of information are verbal. All the things from
which we get information are called sources of information.

We get information and knowledge by reading books.
There are many books which are written in different subjects.
Similarly, we are informed by reading magazines and
newspapers. The books, magazines and newspapers are
available in libraries. So, the libraries, books, magazines and
newspapers are the sources of information.

The radio and television inform us about various events
around the world. We exchange our messages through the
letters. We can talk to our friends and relatives by telephone.
Now-a-days we are using mobile phones for communication.
So, radio, television, telephone, mobile phones and letters are
the sources of information. Now a days computer network is
widely used as a source of information. The internet services
in computer network have made e-mail, voice mail and video
chat possible. The internet services can be used as a source
of information in desktop computer, laptop computer, smart
phones, etc. Similarly, hoarding board signals on the road and
loud- speakers are also used as the sources of information.

Blooming Science, Health and Physical Education Book 4 143

Communication

Theprocessofsendinginformationsormessagefromperson
to person and from place to place is called communication. It
is very important for many purposes. It may be verbal or non-
verbal. Information can be received or sent by different means
of communication. We are using many electronic devices like
radio, mobile phone, telephone and computer as the means of
communication. We also communicate with the help of letters.
Printed materials like books, magazines, newspapers, etc are
also used as the means of communication.

We can have communication by various ways. There are two
types of communication. They are; one- way communication
and two way communication.

One-way communication

In one way communication, we can either send or
receive the information one at a time. Some examples of one
way communication are letter, radio, television, newspaper,
magazine, etc. Some of the means of one way communication
are explained in brief below.

Letters or mail

A letter or a mail is apiece of written or printed paper made
ready to send to somebody. All countries have postal service

144 Blooming Science, Health and Physical Education Book 4

to collect, transport and deliver the mails. We also have post
office for this purpose. A letter is enclosed in an envelope with
addresses of sender and receiver written on it. A stamp (ticket)
is pasted on it to pay the charge. The letter is then dropped in
the post box kept in post office. The post office sends the letter
to the receiver by various ways.

Newspaper

Newspapers are the printed
sheets of paper which contains
news, views, advertisements,
etc. It gives information about
the different fields like national,
international, science, sports,
finance, etc. Newspapers are
published daily, weekly or on a monthly basis. Newspapers
are the cheapest and most efficient means of communicating
information to the public. We should have habit of reading
newspaper on a daily basis because it gives us information
about different things.

Radio

Radio is an audio means of information or communication.
It gives information about different things. We listen to the
radio for news. Radio can provide information to a large

Blooming Science, Health and Physical Education Book 4 145

number of people residing in a wide
geographical area at a time. It can
be used to inform about weather
forecast and natural disasters. Radio
also entertains the people with
music and different programs. We
can not use loud speakers to inform
the people up to longer distances
because the sound can not travel
that far. In radio, sound travels in the form of waves and can
be transmitted upto the long distances also.

Television

Television is an audio- visual
means of communication. On a
television, we can see the moving
pictures with sound. Television
informs us about the news and other
different programmes like that of
radio. Television is also a means of
entertainment. We can see live programmes and live matches
of sports on television. It informs a large number of people
to a long distance at a time. A television can pass the signals
through the satellite.

Two-way communication

The system of communication in which we can receive
and send the information at the same time is called two-way
communication. Telephone, mobile phone, computer network
online chat, video chat, etc are some examples of two-way

146 Blooming Science, Health and Physical Education Book 4

communication. In two way communication, we can send the
message and get the immediate reaction at once. It can be done
in the form of audio by using telephone and mobile phone.
It can be used with audio-visual means by using computer
networks with internet. By using internet, we can have audio-
visual communication by using various types of computers
and smart phones.

Importance of information and communication

Information plays a very important role in our society.
It brings the people in different parts of the world together.
It informs us about different events happening in the world.
Pre-information of certain phenomena makes the people
able to prevent the loss of life and property also. Some major
importance of information and communication are given
below.
1. It increases the level of knowledge.
2. It helps to develop friendship and improves relationship.
3. It is very important to work in group.
4. It makes us familiar to the change occurring in our

surroundings and in the world.
5. It helps to share emotions, sorrow, happiness and new

ideas with others.
6. It helps to know about new places.

7. It helps to be safe from some natural disasters like
hurricane, flood, fire, epidemics, etc.

Blooming Science, Health and Physical Education Book 4 147

Key words a large board used for displaying advertising
posters.
Hoarding board –
a flat paper container for a letter.
Envelope –
Satellite – an artificial body revolving around the earth
to pass the television signals.
Hurricane –
Loudspeaker – a storm of most intense severity.

Epidemics – a device that converts an electrical audio
signal into sound.

a widespread occurrence of an infectious
disease in a community at a particular time.

Main Points to Remember

 The message distributed by a source to one or many people is called information.

 The things from which the informations are conveyed are the means of information.

 Some means of information use verbal way and some use non-verbal ways of
communication.

 The process of sending message from person to person and from place to place is
called communication.

 There are various means of communication. Communication can be done in two
ways; one-way communication and two-way communication.

 Radio, television, letters, newspapers, etc are the means of one-way
communication.

 Telephone, computer network with internet, mobile phone, etc are the means of
two-way communication.

 Information and communication brings the people of the world together and
informs about various happenings.

148 Blooming Science, Health and Physical Education Book 4

Project work

1. Write a letter to your friend or maternal uncle (mama).
Keep it in an envelope, paste a stamp on it and send it
with the help of parents / guardians by using post box/
post office.

2. Listen to the radio and watch television at your home.
Make a list of any four programmes broadcasted from
each in your project work copy.



S.N. Radio S.N. Television
programmes
programmes

1. 1.

2. 2.

3. 3.

4 4.

Exercise

1. Fill in the blanks with suitable words.
a. We get ................ and ................ by reading books.
b. We use ................ to listen news.
c. ................ is the audio visual means of communication.

Blooming Science, Health and Physical Education Book 4 149

d. We read ................ to know the national and
international news.

e. Letter, radio and newspapers are means of ................
communication.

f. We use ................ to talk with people in any part of the
world.

2. Write ‘True’ for correct sentences and ‘False’ for wrong
ones.
a. A library is a source of information.
b. The television is an audio means of
communication.
c. Telephone is a means of two way
communication.
d. Information and communication increases
the level of knowledge.
e. We can send a letter with fixing a stamp on
the envelope.

3. Which information media can be used to relay the following
a. Notice of public holiday throughout the country.
b. Live broadcast of meeting of parliament in audio-
visual form.
c. Printed form of notice in a city.
d. Traffic symbols to drivers.
e. Advertisement to the public nearer to the highway.

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