The Earth

There is one ball you can stand on easily, because it is so big. It is the ball we live on, which we call the earth.

Some of the earth is covered with land, but most of it is covered with water. We call the big areas of land the continents, and the big areas of water the oceans, or seas. We live on Islands next to the continent of Europe with the Atlantic Ocean to the west.

All around the earth there is a layer of air, which we call the atmosphere. When we go above the atmosphere, we are in Space. So the earth is a huge ball of rock , water and other things, surrounded by atmosphere and moving in Space.

Gases

There are gases all around us. They are the gases that air is made of. We can't see the air, we can't touched it, and we can't taste it. But we can feel it and hear it when it moves. We can also feel the air pushing against us when we cycle or run fast.

Air is one of the most important things on earth. We must breath air to live. Without air, we would die. Underwater and out in Space there is no air. We can only go there if we take air with us.

People who dive under the water take air with them in metal bottles. We can squeeze a lot of air into the bottles. This is compressed air. We can squeeze all gases in the same way, but we can't do this to liquid or solids.

Science

You know guy's that the word science come from the Latin word scire which means ''to know''. This is not just things we know about the world. It is an organized way of knowing and investigating the world. To satisfy our curiosity about the world, scientist always ask questions. They also try to explain why things happen. They believe that nothing happens without a cause. However, there are people who still maintain that this is not always the case.

For example, we might have observed our grandparents and other people carry out some unusual practices and beliefs. This belief and practices have been passed on to our parents too, some of these beliefs and practices have logical or scientific explanations while some have no scientific basis at all.
The beliefs and practices that have no scientific basis are called Superstitions.

Putting energy to work

We use energy to do work. Try making a simple toy that puts energy to work.

1. Push the rubber band through the hole in the middle of the cotton reel. Break the matchstick in half and push a piece through the loop of the rubber band. Tape the matchstick to the cotton reel, so that it cannot turn.

• An empty cotton reel
• A matchstick
• A rubber band
• A piece of sticky tape
• A round bead
• A pencil about 10 centimeters long
  
  

2. At the other end, pull the rubber band through the bead with an unbent paper clip, and then push the pencil through the loop. The rubber band should be holding everything together, so0 if it's too loose find another the right length.

3. Wind the pencil round ten times and let go of the cotton reel on a flat surface. What happens?


The rubber band makes the cotton reel move, but where did the energy of the rubber band come from? What difference does the number of turns in the band make?Try it with 20,30 or 40 turns. Does changing the length of the pencil make any difference?You could try making a bigger machine from an empty washing-up liquid bottle.

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Underground electricity cables

If you look up a torch bulb closely, you will see that there is fine wire inside, which lights up when electricity passes through it. The electric bulbs we use to light up our homes are the same, but they use a much stronger kind of electricity . This comes into our homes through thick wires, or cables.

Main electricity is very useful but it is very dangerous. Never try to look inside electric plugs and sockets or play about with any electrical equipment . You could get an electric shock that would hurt you.

When you press the button on an electric bell, electricity from the battery makes the striker hit the bell.

Electric Current

When i go outside at night, i need to take a torch with me to see where me are going. When i switch on the torch, it lights up. The light is made by electricity. This is not the same as static electricity, but is the sort of electricity which flows through wires and other pieces of metal. When electricity flows, i say there is an electric current.

In a torch the electricity comes from a battery. A battery makes electricity when chemicals inside it join together. Have you anything worked by batteries?

If i took a torch to pieces, i would find that it has many parts. It is made up of a bulb, one or two batteries, and a switch. These parts are joined together by pieces of metal. The metal makes a path where electricity can flow from the battery to the bulb, and back. This kind of path is an electric circuit which usually has a switch in it. When the switch are turned 'OFF', it leaves a gap in the circuit and no electricity can flow through.