Centre Travel

Air Air is all around us - it surrounds the earth in a layer called the atmosphere.  All living things must have air in order to live.  Air is colourless and has no smell,  Yet it is really a mixture of a number of different gases. We can feel air when the wind blows, and we know air has weight.  Air carries sounds - without it we would not be able to hear because sounds cannot travel in a Vacuum. The chief gas in air is nitrogen, which makes up nearly four-fifths of the air.   About one--fifth of the air is made up of Oxygen.  Air also holds some water particles called vapour.  We find the degree of Humidity in the air by measuring the amount of Vapour. Air expands when it is heated, and when it expands it becomes lighter. This is why warm air rises. The air that surrounds the earth gets thinner and higher you go.  All high-flying aircraft have to keep the air in their cabins at ground -  level pressure so that passengers can breathe normally.  In the same way, mountaineers

Abbreviation An abbreviation  is a shortened form of a word or a group of words.  Words and phrases are shortened to save space.  Sometimes only the beginning of the word used, such as St for "Saint" or DR for "doctor"  Sometimes only the beginning of the word is used as in Sept  for "September". A full stop may be placed after the abbreviation to show that it is shortened form.

The abacus is a simple counting machine first used by the ancient Greeks and Romans.  It consists of rows of beads strung on wires:  those on the first wire count as ones, those on the second wire count as tens, and on the third they count as hundreds, and so on.  The abacus is still used in Eastern countries such as China and Japan.  The Romans sometimes used small stones as counters.  They called these counters calculi, and it is from this that we get our word calcuate.

There are thousands of different kinds of bacteria.   These tiny living things are too small to be seen with the naked eye.   They are one of the simplest forms of life and are more like plants than animals, though they show characteristics of both. Bacteria take many shapes.  Some are round, others are wormlike or spiralled.  Still others are red-shaped. These microscopic organisms are found everywhere - in our bodies, in the soil, in food, on just about everything we touch. Many bacteria are helpful.  There are bacteria in the soil that help to break down, or decay, animal and vegetable matter.  Those in our digestive systems help break down food nutrients for the body.  Harmful bacteria include germs that cause disease and those that make food spoil.   Bacteria multiply very quickly.  From one bacterium there can be millions in only a few hours.  Louis Pasteur was the first to study the effects of bacteria and to discover  that  it was the bacteria that made food spoil.

The Human Body Where bones meet there is always a joint.  There are immovable joints, as in the skull; slightly movable joints, as in the spine; and hip.  Where one bone rubs against another there is a tough substance called cartilage and the joints , are lubricated by a special fluid called synovial fluid.   Joints are held together by tough stretchy ligaments.

Cactus There are many different cacti, they are able to grow in hot Desert climates.  Cacti can do this because they store water in their fleshy stems.  They are covered with prickly spines instead of leaves.  The spines protect the plant's store of water from desert animals.

The body of the Red Fox:  Ears are large to pick up as much sound as possible. A fox can hear even better than a dog. Nose  The fox 's sense of smell is very keen. With its wet nose it can tell which way the wind is blowing, so it knows exactly, where any smell is coming from. Teeth  Long ones at the front for tearing meat and sharp side ones for slicing it. Tail   The fox's tail is called a brush.  It helps it to balance; and to signal to other foxes, and to keep warm, curling it round like a scarf. Legs   Strong legs and feet for running.  The fox does not run away very fast, but it can run for a long time at the same speed