Humans play a big role in causing desertification. They keep too many animals, such as cows, on their land. They also cut down too many trees, so that new trees cannot grow. It is important to try to change these destructive practices. If they continue, more and more land will be permanently ruined. (From Reading Challenge 2, Book 3)

    Do you believe that seven is a lucky number or that bad luck happens in sets of three? If so, your ideas are as old as Pythagoras, a Greek philosopher who lived 2,600 years ago. Pythagoras believed that certain numbers and their multiples had mystical power. For centuries, people have given importance to numbers and developed superstitions about them. Many of these superstitions have been passed on throughout the generations and still exist today. 

    Numbers don’t have the same meaning in all cultures. Five is considered a holy and lucky number in Egypt. But in Ghana, the Ashanti people considered five to be an unlucky number. To give someone five of anything is to wish the person evil. The ancient Greeks and Egyptians thought the number four was a perfect number symbolizing unity, endurance, and balance. However, the Chinese consider the number four to be unlucky because it sounds like the word for death. 

    There are many superstitions regarding the number 13. For example, in Britain it’s considered a bad omen for 13 people to sit at a table. Some say that the person who rises first at this table will meet with misfortune, even death, within a year. Other says it’s the last person to rise. Some British people think it’s unlucky to have 13 people in a room, especially for the person closest to the door. The thirteen day of the month isn’t considered a good day on which to begin any new enterprise, including marriage, or to set out on a journey. Many people believe that Friday the thirteenth is the unluckiest day in the year. This belief is so widespread that there are horror movies called Friday the Thirteen. 

   From ancient civilizations to modern societies, the belief in the magic of numbers has persisted in spite of the advances in science and technology. There is nothing quite as stubborn as superstition. Even today, in the twenty-first century, people still believe in bad luck and omens. In the future, people may work in space stations or travel the universe in starships, but there probably won’t be a “Starbase 13” or a rocket liftoff on Friday the thirteen. A seventh voyage will be a good one, and the third time around will still be lucky.