Laurie Sandston, age 15, of Albuquerque, N.M., for her question:

IS CHINA'S CIVILIZATION THE WORLD'S OLDEST?

China has the oldest continuous civilization of any country in the world. One reason that China's long history goes back about 5,000 years is that for much of the time it was physically isolated from other countries. Surrounding Chins on all sides were physical barriers or wastelands that limited contact with the outside world.

Because China was cut off from the rest of the world, the Chinese regarded their country as the center of the world culture. Their country was called "Chung kuo," which means "Central" or "Middle Kingdom." The isolation served as protection.

Although China fell behind the West in economic development in the past 200 years, for mote than 2,000 years before that China was one of the most advanced countries in the world.

The official name of the nation today is the People's Republic of China, and since 1949 it has had a Communist government. One of the objectives held by the current leaders of China is to again see the country restored to its former position of influence and power.

There are many impressive facts regarding China. One is that China is the world's first country to have a population that passed the 1 billion mark. This information came out of a 1982 national census. Since the 1960s there had been a great decrease in the death rate.

Another impressive fact is that China is the third largest country in area in the world. The country has an eastern coastline that measures 2,700 miles. China is 3,000 miles wide from east to west and 3,400 miles at its longest north to south measurement.

Historians agree that people are China's greatest resource because of their strong cultural traditions and unity. They form a large source of labor for China's farms and factories. The people are extremely dedicated and they also believe in working very hard.

One of China's problems is that only 10 to 12 percent of the country can be used for growing crops, providing less than one third of an acre of cultivated land per person in China. This is an extremely small amount of land. It means that the people have to work especially hard to grow enough crops to feed the people as well as to meet the needs of Industry.

Another problem is that about 96 percent of the people crowd into only about 40 percent of the nation's land area. Most of the people live In the plains and lowlands in the east.

Home for the Chinese people originally was the Wei River Valley, a tributary of the Yellow River in north China. The Chinese first became a distinct cultural group about 5,000 years ago. The first settlers were most likely members of a Mongoloid race from the grasslands of Mongolia.

At first the settlers were herdsmen. Gradually they changed their way of living to settled agriculture. They grew wheat and developed irrigation.