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Natural sciences

Grade 4

Planet earth and the universe

Module 45

Stormy weather

Activity:

Learning about stormy weather conditions

[lo 2.1, 3.1]

Stormy weather

:

What do you do when the weather is stormy? Tell the class about funny stories related to storms.

Dark clouds converge in the air. Heavy rains fall to the earth. Now and again there is a bright flash of lightning and we hear the roar of thunder. But what is actually happening?

Clouds:

The air is full of small dust particles. Water drops form around such dust particles and then form clouds together with millions of other drops.

Try the following:

Mark an empty bottle in mm and place it outside when it rains.

Lightning:

During a storm strong winds blow the small water drops that have formed around the dust particles, into the centre of the clouds where they bounce against each other. Each of the small particles of a cloud has either a positive or negative electrical charge. When the particles bump against each other the charges separate. The majority of the positive charges move to the top of the cloud and the negative charges move toward the bottom of the cloud. Lightning is a massive electrical spark in the cloud. This spark occurs when the negative charges in one cloud come into contact with the positive charges in another cloud or with the ground.

Thunder

Thunder is the loud noise that you hear when warm air and cold air suddenly come together. When lightning brightens the sky, it also heats the surrounding air. When this hot air comes into contact with the cold air, a gigantic wave of moving air causes the clap of thunder.

Dangerous weather

Tornado

This is a very strong wind that is caused when a front with cold and dry air comes into contact with warm, moist air. It causes a large black cloud in the air. The warm air rises rapidly and more warm air moves in below it to replace it. Sometimes the rising air begins to move in a spiral and a tornado develops. If a tornado reaches the ground, it causes incredible damage because it sucks up everything that it encounters on the ground into the air.

Hurricane

This is a very big storm that starts on the surface of tropical seas. It consists of a large quantity of wind and rain that begins to spin around its centre, which we call the “eye”. It moves forwards as it rotates and creates enormous waves that are very destructive.

Cut A4 sheets of paper into four (into quarters) to have one small sheet of paper for each learner in the class. Each learner must draw an aspect of the weather on his or her piece of paper. Work clearly and neatly. Stretch a washing line across the classroom and hang the drawings of the “weather conditions” from the line!

Assessment

LEARNING OUTCOME 2 : CONSTRUCTING SCIENCE KNOWLEDGE The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

Assessment Standard

We know this when the learner

2.1 recalls significant information.

LEARNING OUTCOME 3 : SCIENCE, SOCIETY AND THE ENVIRONMENT The learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment.

Assessment Standard

We know this when the learner

3.1 understands science and technology in the context of history and personal knowledge.

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Source:  OpenStax, Natural sciences grade 4. OpenStax CNX. Sep 18, 2009 Download for free at http://cnx.org/content/col11096/1.1
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