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00:00Air is very important for all living things.
00:10We cannot survive without air.
00:13In this chapter, we will study more about air which is invisible and has no definite
00:20shape.
00:21Air is a mixture of gases.
00:27It is made of gases like oxygen, carbon dioxide, nitrogen and water vapour.
00:35We need oxygen to breathe and carbon dioxide is used by plants to make food.
00:43Air has weight.
00:45Take a stick which is 1 meter long.
00:51Take two blown up balloons and tie their strings at the two ends of the stick.
01:00Balance the stick by shifting the positions of the balloons.
01:08A small slit is made in one balloon, so air may slowly escape from it.
01:19When all the air has escaped from one balloon, the other balloon with air in it goes down
01:27and the stick is not balanced now.
01:31From this, we can conclude that air has weight.
01:40Air is needed to make things burn.
01:43Oxygen is needed for burning.
01:46If you cover a burning candle with a glass, it will stop burning after some time.
01:53It needs more air to keep burning.
01:59Air has dust particles.
02:01When vehicles move or a sweeper sweeps the road, dust particles rise up and mix with
02:10the air and pollute the air.
02:13Air pollution.
02:15If the air around us contains dust, smoke and germs, we say that the air is polluted.
02:24The smoke coming out of vehicles like bus, truck or car also mixes with the air.
02:33The smoke coming out of the chimneys of factories or bakeries also mixes in the air.
02:42Checking air pollution.
02:44In order to check air pollution, we should check our vehicles regularly.
02:51We should not burn wood, coal and other similar things.
02:56Garbage should be thrown in covered dust bins.
03:01To get clean and fresh air, keep the windows open with wire net.
03:07It will allow the fresh air to come in.
03:12We need clean and fresh air to be healthy.
03:17Always go for a morning walk.
03:20Morning air is fresh.
03:25Keep the surroundings clean.
03:28It will keep the air clean.
03:31Grow green plants where we live.
03:34Plants make the air fresh and clean.
03:39Play out in the open.
03:41It will give you fresh and clean air which makes you healthy.
03:52Do not cover your face while sleeping.
03:56Wind.
03:57Moving air is called wind.
04:02Wind is a natural source of energy.
04:05We cannot see the wind.
04:07We can feel the wind.
04:10When the wind blows fast and hard, it is called a storm.
04:16When the wind blows slowly and gently, it is called breeze.
04:23Hot winds of summer are called loo.
04:27Wind has direction.
04:30We can find out the direction in which the wind is blowing.
04:35Take some sand on the table and switch on the fan.
04:40It gets blown in the direction of the wind.
04:43We can also find the direction of the wind by looking at the movement of the branches
04:50of the tree.
04:51A kite moves along the direction of the wind.
04:55Summary.
04:56Air is very important for all living things.
05:01Nobody can see air but can feel it.
05:07Air is a mixture of many gases.
05:10We should not pollute the air as we all need to breathe it.
05:17Polluted air carries many diseases.
05:21Garbage should be thrown in covered dustbins.
05:26Keep the surroundings clean.
05:29Plants make the air fresh and clean.
05:34Moving air is called wind.