Water on the Earth (p3)

Jesús Manzaneque & María Montes

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1.- We need water to live
All living things need water. Plants and animals die very quickly if they do not have water.
● Land animals and people drink water.
● Land plants absorb water through their roots. If they do not have water, they dry up and die.

2.- We need water to live
Most of the water on the Earth is in the sea.
There is also water on land. This is the
water you use for drinking and watering your
gardens. Water is found in two different
● Surface water. This water is found
in rivers, lakes and streams.
Underground water. This water is found
under the ground. Water falls on the land
and then filters through the ground
to underground deposits. These are like
rivers or lakes under the ground.
There is also water insnow, and inclouds,
and in the iceat the poles.
The source of a river. In this picture, underground water comes to the surface and becomes the source of a river.

3.- The states of water
Water can be found in three different
states: liquid, solid or gas.
● Tap water, river water and sea water is
water in its liquid state.
● Ice and snow is water in its solid state.
● Steam is water in its gaseous state.

4.- Changing states
A change in state takes place when waterpasses from one state to another. In order for this to happen, the water has
to be cooled or heated.
● If we heat ice, it turns into water. This change is called melting.
● If we cool water, it becomes ice. This change is called freezing.
● If we heat water, it becomes water vapour. This change is called evaporation.
● If we cool water vapour, it becomes water again. This change is called condensation.



5.- Water moves around the Earth
Water is always moving around the Earth. It moves from the sea to the sky, the sky to the land, and from the land back to the sea.
It also changes state from one place to another.
This movement and the changes in state are called the water cycle.
Storm clouds. Clouds are made up of tiny drops of water. These come from water vapour in the air.

6.- Water moves from the sea to the sky
The water in the sea, rivers, and lakes evaporates little by little. This is due to the heat from the Sun.
The water vapour, which is produced during this process, rises and gets colder. When it gets cold, it condenses, and becomes liquid water again. The tiny drops water form clouds.
Hailstones. These are more common in Spring and Summer.
7.-Water moves from the sky to the land
The clouds are blown from one place to another by the wind. Itrains when a cloud is very heavy with drops of water and these water drops get colder. If it gets very cold, or it gets colder very fast, then,
instead of rain, we have snow orhailstones.
This is how water moves from the sky to the land.
The water cycle. Sea water evaporates. Water vapour forms clouds. The water in the clouds falls back to the land. Streams and rivers carry the water back to the sea. Underground water makes rivers in caves and dampens the lower layers of soil.

8.- Water moves from the land to the sea
Water from rain and snow (when it melts) follows two possible routes:
● Some of the water travels into streams, which flow into rivers and then the sea.
● The rest of the water filters down to underground water deposits. When this water reaches the surface again, we call it a spring. This water then flows to the sea.

water cycle.flv


9.- Water in rivers
Water in rivers is always moving. Rivers start in the mountains and flow into the sea, a lake or another river. Rivers which flow into other rivers are called tributaries.
The course of a river is the route it follows from the source to the mouth. The river bed is the ground over which a river flows.
The flow is the amount of water that a river carries.

10.- The journey of a river
A river has three main parts or courses:
● The upper course of the river is near the source. Here, the river is narrow. It carries only a little water, and it moves very fast.
● The middle course of the river flows through areas where there is not much change in altitude. This part of the river is wider, it carries more water, and it flows more gently.
Sometimes the river bends and twists in this part. These bends are called meanders.
● The lower course of the river is where the river meets the sea or a lake.
This part of the river is very wide, and the water moves very slowly.
11.- Rivers are very useful
Rivers are very important for people for several reasons.
● Rivers provide us with waterfor drinking and for irrigating crops.
● Water from a river can be used to make electricity.
● Many fish live in rivers.
● We can use rivers for water sports.

12.- Lakes and reservoirs
We can find water in rivers, lakes and reservoirs.
Lakes are huge areas of water surrounded by land. Small lakes are called lagoons.
Reservoirs are man-made lakes. We make reservoirs by building a wall, called a dam, across a river. This creates a man-made lake and keeps the water in.
We store the water from rivers in reservoirs.
This water is then transported from one place to another by canals. Canals are man-made rivers.

Interesting water facts

Escaping Water experiment

Water Cycle Game

Games and activities

More games and activities

Water on the Earth