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For the Teacherhtml5e=mc2Tell the students about air, water and weather. Also ask them some
questions based on the previous knowledge that they have learnt in
previous classes.

2. Land Breeze Land breeze

At night reverse process takes place. Land cools
down quickly. But water in sea is warm as it
cools slowly. So the air above the water is also
hot. As the hot air is light, it rises up. The cool
air from the land flows to occupy the space of
warm air. This is known as Land Breeze.

Water

About three-fourth of the earth is covered with water. It exists in three forms namely,
snow, water and water vapour.
The states of water can be changed by the processes like evaporation, condensation
and freezing.

Evaporation

When you put the wet clothes in the sun, you observe that after a few hours they get
dry. Where does the water in clothes go? Water of clothes changes into water vapours
by the heat of the sun. This process of change of water into water vapours is called
evaporation. The water in rivers, lakes and oceans gets evaporated by the heat of sun.

Condensation

You might have seen some water droplets on the lid of pan while water is boiling or
food is cooking in it. It happens due to the change of water vapours into water. This
change of water vapours into water is known as condensation.
Condensation takes place in nature too. Clouds, dew, fog and snow are its examples.

Freezing

Freezing is the process in which liquid water changes into snow.

Purification of Water

Impure water can make us fall ill. So we should always drink pure water. Water can be
purified in the following ways:

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