Science notes, unit 9

Earth

Textbook Science Year 2 (DLP), pages 101–116

What this chapter covers

{'You can name the natural sources of water': 'rain, rivers, lakes, seas and springs (9.1.1)'}
You can say that water flows from a high place to a low place (9.1.2, 9.1.3)
You can say how rain, rivers and the sea join in the natural water cycle (9.1.4, 9.1.5)
You can say that air is around us and that living things need air to breathe (9.2.1, 9.2.2)
You can say that moving air is wind and how wind helps people (9.2.3)
You can give an effect of strong winds and describe a simple wind rocket (9.2.4, 9.2.5, 9.2.6)

Water and air are the basic sources of life. In this unit you will find out where water comes from, where it flows, and how air and wind help us.

9.1Water

Natural sources of water

The natural sources of water on Earth are rain, rivers, lakes, seas and springs.

Source	What it is
Rain	Water drops that fall from the clouds
River	A stream of water made when rain falls to the earth
Lake	A large area of water with land all around it
Sea	A big part of the earth covered with salt water
Spring	A place where water under the ground flows out

A grey rainy sky and a blue lake surrounded by land — Rain and a lake.

Water bubbling out of the ground between stones — A spring (left) and a river (right).

A river winding through green forest — A spring (left) and a river (right).

Did you know? Sea water is salty. Rain, river and lake water are not salty.

Name three natural sources of water.

Show answerHide answer

Any three: rain, rivers, lakes, seas, springs.

Water flows from high to low

Water always flows from a high place to a low place.

Four photos: coloured water poured into a tray, then one side of the tray raised and the water running to the low side — Lift one side of the tray. The coloured water runs down to the low side.

Rivers and waterfalls flow from highland (hills and mountains) to lowland. Then they flow into the sea.

A picture of a river starting at a waterfall on a high mountain, flowing across lowland to the sea — A river flows from the mountain, down to the lowland and into the sea.

Water does not flow uphill by itself. It flows down.

The natural water cycle

The natural water cycle is a cycle that never stops. It gives water to living things and cools the earth.

Water in the sea and rivers is heated by the sun.
It turns into water vapour and rises up.
The water vapour cools and makes clouds.
Heavy clouds give rain. Rain flows back to rivers and the sea.

Picture of the natural water cycle: 1 water, 2 water vapour, 3 clouds, 4 rain — Water, water vapour, clouds, rain. Then it starts again.

Put in order: rain, water vapour, clouds, water.

Show answerHide answer

Water, water vapour, clouds, rain.

9.2Air

Air and living things

Air is all around us. It is also in water and in soil. Air has gases such as oxygen and carbon dioxide.

Living things need air to breathe. Humans, animals and plants breathe. Fish breathe in water and termites breathe in the soil.

A boy blowing up a balloon, a man fishing, and termites in the soil; air is around them all — Humans, plants, animals, fish and termites all breathe.

A tree, a buffalo and a fish; living things breathe — Humans, plants, animals, fish and termites all breathe.

We need oxygen to breathe. We breathe out carbon dioxide.

Moving air: wind

Moving air is called wind. We cannot see the wind, but we can feel it.

The wind helps people:

It helps a kite fly high.
It moves a sailing boat.
It turns a windmill.
It dries clothes on the clothes line.

Children flying a kite on a beach, and a sailing boat on the sea — The wind flies the kite and moves the sailing boat.

Wind turbines in a field and white clothes drying on a line — Wind turns the windmills and dries clothes.

Strong winds

A very strong wind can cause big waves and storms. It can hurt people and break houses.

Big waves near a house by the sea in a strong wind — Strong winds make big waves.

Wind rocket: cut out a paper rocket, tape a short straw to it, and put a long straw into the short straw. Blow into the long straw. Moving air makes the rocket fly!

Pictures: Science Year 2 (DLP) textbook, pp. 102-104, 105-107, 108-109, 110-111 and 112-113.

Summary

Idea	Remember
Natural sources of water	Rain, rivers, lakes, seas, springs
Direction of water flow	High place to low place
Water cycle	Water, water vapour, clouds, rain
Air	Living things need air to breathe
Wind	Moving air; flies a kite, moves a boat
Strong wind	Big waves, storms