What do you know about the sea? Some people have seen it but others haven't. The sea looks beautiful on a fine sunny day and it can be very rough when there is a strong wind. What other things do you know about it?

    Of course, the sea is very large. In the world there is more sea than land.

    If you have swum in the sea, you know that the sea is salty. Rivers carry salt from the land into the sea. Some places of the sea are saltier than the other places. Do you know the Dead Sea? It is so salty that you can't sink when you are in the water! And fish cannot live in it!

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    Nobody can live without the sun. The sun gives us light and heat, then light and heat give us life. Without the sun, we would be in complete darkness. Without light and heat, the Earth would be very cold and would be all snow and ice. Then all plants, animals and men would die.

    We can't live without light and heat. Yet, if the sun is always shining upon us, we can't bear it, either. The Earth would be too hot to live on.

    We need the night to bring us rest and sleep. We do not have the sun at night, because our Earth is always turning around the sun and only one side of the Earth sees the sun at one time. When we see the sun on the side of the Earth, it is day to us. When we can't see the sun, it is night.