Olympic Games

Every four years, athletes from around the world come together to compete in the Olympic Games. Do you know why this event is called the Olympics? The games were first held at Olympia in ancient Greece. The ancient Olympic Games honored the Greek god Zeus. Today, the Olympic Games are held in different cities around the world.

THE ANCIENT GAMES
We know that the ancient Olympics began as far back as 776 BC. That’s when the Greeks began keeping records of the winners. Theancient Games continued until about AD 392, more than 1,000 years! Athletes came from cities throughout Greece to compete in races, boxing and wrestling matches, gymnastics, and weightlifting. They also threw spears, hurled a discus (bronze disk), and jumped for distance. Wealthy Greeks raced their horses. Winners were crowned with wreaths of olive or palm leaves.

The ancient Olympic Games were not just a sporting event, however. There were competitions in poetry, music, speechmaking, and other arts as well. At the beginning and end of the Games, animals were sacrificed (killed and offered) to Zeus. A splendid temple was built at Olympia in Zeus’s honor. When people stopped worshiping the Greek gods, the Olympic Games were canceled.

THE MODERN GAMES
The Olympic Games were brought back in 1896. The first modern Olympic Games were held in Athens, the capital of Greece. Only nine countries participated in the first Games, and all the athletes were male. Today, some 10,000 athletes compete in the Olympic Games, and nearly half of them are female. They represent about 200 nations. At first, the modern Olympics included only summer sports, such as swimming, rowing, and track and field. Figure skating was
added in 1908, and ice hockey in 1920.

The first winter Olympic Games were held in 1924. More winter sports were later added to the Winter Games, including downhill skiing, bobsledding, and ski jumping. Snowboarding and freestyle skiing followed in the 1990s. From 1924 through 1992, the Winter Games and the Summer Games took place in the same year. After 1992, the next Winter Games were moved up two years, to 1994. Winter Games and Summer Games now occur two years apart. Each of these Games takes place every four years.

GOING FOR THE GOLD
After each Olympic event, medals are awarded to the competitors who finish in first, second, and third place. First-place winners receive a gold medal. Those who finish in second place receive a silver medal, and those in third place, a bronze medal. Olympic athletes often dazzle the world. In 1912, Jim Thorpe of the United States won the gold medal for two of the most difficult contests in track and field: the pentathlon, which consists of five different events, and the decathlon, which consists of ten events. Thorpe is still the only athlete to have won the pentathlon and decathlon at the same Olympics. In 1932, Babe Didrikson of the United States became the only Olympic athlete ever to win medals in separate running, jumping, and throwing events. Four years later, African American track star Jesse Owens won four gold medals. During the 1970s, the thrilling performances of Olga Korbut of the Soviet Union and Nadia Comaneci of Romania inspired a generation of girls to take up gymnastics. Also in the 1970s, American Mark Spitz amazed the world by winning a total of seven gold medals in swimming. Sarah Hughes in 2002 charmed audiences as she skated her way to a gold medal.

Nelson Mandela

Nelson Mandela, a boy from an African village, grew up to become the first black president of South Africa. Before he became president, Mandela led a long and difficult struggle against segregation in South Africa. Under segregation, black and white people were kept apart. Segregation denied blacks many basic rights. Mandela spent many years in prison for trying to end segregation in South Africa.

EARLY LIFE
Nelson Rolihlahla Mandela was born in 1918 in a small village in the Transkei region of South Africa. His father was a chief of the Thembu tribe. Mandela’s parents named him Rolihlahla, an African word that means troublemaker. Little did they know how fitting his name would be! At the age of seven, Mandela became the first person in his family to go to school. At school, Mandela was given the name Nelson. He went on to attend collegeand earn a law degree in the city of Johannesburg.

FIGHTING SEGREGATION
When Mandela was a young man, South Africa was divided by segregation. Segregation in South Africa was called apartheid, a word that means apartness. Under apartheid, black people couldn’t vote or hold certain jobs. Whites controlled the government. Blacks and whites lived in separate areas and went to different schools. Mandela opposed this cruel and unfair system. In 1944, Mandela joined a group called the African National Congress (ANC). The ANC opposed the rule of South Africa by whites alone. The ANC believed that South Africa belonged to everyone, whatever the color of their skin.

A NATURAL LEADER
Mandela was a natural leader and a gifted speaker. He became a leader in the ANC, and he encouraged people to break the apartheid laws. The government saw Mandela as a troublemaker. It tried to stop him. The government made the ANC illegal. Mandela was arrested several times. When he was released, he continued to fight for an end to apartheid. In 1962, the government sentenced Mandela to five years in prison. Then, in 1964, he was accused of working to overthrow the government. The government increased Mandela’s sentence to life in prison.

MANDELA IN PRISON
The government sent Mandela to a prison on Robben Island, off the coast of South Africa. The prison conditions were harsh. Mandela was allowed only one visitor every six months. Every day he was forced to break rocks in the prison yard for many hours. During this time, Mandela became the world’s most famous political prisoner. Leaders around the word demanded Mandela’s freedom. They wanted apartheid in South Africa to end. In 1982, the government moved Mandela to a prison on the mainland. This was during a time of growing violence in South
Africa. Many people protested in the streets against apartheid.

PEACEMAKER
The government began secret talks with Mandela. They believed that if anyone could stop the trouble, Mandela could. He was a popular leader who had won the support of many South Africans. In 1990, Mandela was released after spending 27 years in prison.The government lifted the ban on the ANC. Mandela became its leader in 1992. Mandela soon began talks with the government aimed at ending apartheid. Many white people worried about giving blacks equal rights. Mandela worked with South Africa’s president, F. W. de Klerk, to promote peaceful relations between blacks and whites. For their efforts, Mandela and de Klerk won the Nobel Peace Prize in 1993.

PRESIDENT OF SOUTH AFRICA
In 1994, South Africa held elections. For the first time in South Africa’s history, men and women of all races could vote. Mandela became the first black president of South Africa. He brought an end to the hated apartheid system. After five years as president, Mandela retired from political office. He returned to live in the Transkei region, where he grew up.

Islam

Islam is the second largest religion in the world. Only Christianity has more followers. People who follow the religion of Islam are called Muslims. Today, almost 1 billion people call themselves Muslims. Most Muslims live in a string of countries that extends from Morocco in North Africa to
Indonesia in Southeast Asia.

BIRTH OF ISLAM
An Arab trader named Muhammad was the founding prophet of Islam. He lived in Mecca, a busy trading town in Arabia (now called Saudi Arabia). Mecca had temples built to honor various pagan gods. Pilgrims visited these temples to worship statues of the gods. One day, while fasting in a cave, Muhammad had a vision. He returned to Mecca to preach a new religious message. He said there is only one god, not many, and no one should worship idols (statues of gods). He called on the people of Mecca to surrender themselves to Allah, as he called God.

ISLAM GAINS POWER
Muhammad’s message angered some Meccans. In the year 622, they forced him to flee to another city, now known as Medina. That journey—or Hegira, as Muslims call it—marks the beginning of the Islamic calendar. In Medina, Muhammad became the head of the community. Soon, he led his Muslim followers back to Mecca. After a battle, the Meccans accepted Islam. Within a century, Muslims ruled an empire that stretched from India to Spain. Throughout this empire, Islam took root. The empire crumbled after a few centuries, but many people of these lands remained Muslims.

ISLAM DIVIDES
After Muhammad’s death in 632, Muslims disagreed about how the next leader should be chosen. One group came to be known as Sunnis and the other as Shias. Islam remains divided into these two branches. By the year 900, a Muslim movement called Sufism had developed. Sufis seek a personal experience of God. Many great Muslim poets have been Sufis. Sufis helped to spread Islam long after the Islamic empire crumbled.

WHAT DO MUSLIMS BELIEVE?
The Muslim faith centers on five beliefs and practices. These are known as the five pillars of Islam. According to the five pillars, Muslims must
1. Accept that only one God exists and Muhammad was his messenger.
2. Perform certain prayers five times a day.
3. Fast from dawn to dusk during a month called Ramadan.
4. Give a portion of their wealth to the poor.
5. Visit Mecca at least once if they are able to. These practices are based on the holy book of Islam, the Qur’an (also spelled Koran). Muslims believe that the Qur’an is the word of God, delivered through Muhammad. Muslim practices are also based on the Hadith—Muhammad’s own deeds and sayings as eported by his companions.

ISLAMIC LAWS AND CUSTOMS
In the early Islamic empire, the government and the religion were he same. All questions that came up were decided by religious scholars. Their decisions filled in a set of laws called the Sharia. These laws, which are also drawn from the Qur’an and Hadith, cover every aspect of life. They tell what crimes should be punished and how. They set the rules for marriage, contracts, and inheritance. Islam is thus a complete way of life. In this way of life, men and women generally have different roles. Their activities are often kept quite separated. Families sometimes arrange marriages. Women are expected to be well covered when they go outdoors. In some countries, they have to wear a veil covering their body. In Arab countries, such a covering is called a burka. The mosque is the traditional place of worship for Muslims. Friday is their holy day, or day of worship. Islam teaches that all Muslims are equal before God. This teaching gives Muslims around the world a sense of community, no matter what country or social class they come from.

Amphibians

Say you are thirsty. Can you put your hand in a glass of water and drink it through your skin? Of course you can’t! But some animals can absorb water this way. These animals are called amphibians. Amphibians are very interesting creatures. They live a kind of double life. They spend the first part of their life in water and the second part on land. In fact, the word amphibian
comes from two Greek words that mean “both” and “lives.”

KINDS OF AMPHIBIANS
An amphibian is an animal that has moist, hairless skin. Amphibians are cold-blooded, which means they cannot make their own body heat. They get warm in the sun and cool off in the shade. The three main groups of amphibians are frogs and toads, salamanders, and caecilians. All amphibians have backbones. The three kinds of amphibians look very different from each other.
Frogs and toads have legs but do not have tails. Salamanders have short legs and long bodies ending in tails. Caecilians do not have any legs. They look a lot like big earthworms. There are more than 4,000 different species (kinds) of amphibians in the world. Nearly all amphibian species are frogs or toads. Toads differ from frogs in the roughness of their skin. Toads have bumpy skin, and frogs have smooth skin. Toads also have shorter legs than frogs. The biggest amphibian found on Earth is the Japanese giant salamander. It can grow to be longer than 5 feet (1.5 meters). Tiny frogs, such as the gold frog, are only about 0.4 inch (about 1 centimeter) long.

THE DOUBLE LIFE
Most amphibians start out as larvae. Larvae look totally different from adult amphibians. Frogand toad larvae are sometimes called pollywogs or tadpoles. These larvae look more like fish. They live underwater and have a tail that they use for swimming. They breathe through gills to get oxygen from the water. An amphibian’s body changes completely when it goes from a larva to a grown-up. This kind of change is called metamorphosis. Most grown-up amphibians have lungs for breathing instead of gills. Some have both lungs and gills. Full-grown amphibians have legs for moving about on land. Frogs and toads have strong hind (back) legs for jumping. Most salamanders have four short legs and a long, strong tail. The tail helps them keep their balance while walking and pushes them forward while swimming. Caecilians never grow legs. They use their hard heads as battering rams when they burrow in the soil. In water, they swim as eels do, by wiggling their wormlike bodies back and forth. AMAZING SKIN Amphibians can “drink” through their skin. The skin of an adult amphibian is able to absorb water from its surroundings. Most amphibians do not even swallow water. Their skin soaks up as
much as they need. Amphibians also breathe through their skin. Their skin takes in oxygen as well as water. Most grown-up amphibians get oxygen through both their lungs and their skin. But some salamanders get all their oxygen through their skin. They do not even have lungs or gills. Slimy stuff called mucus covers an amphibian’s skin. The mucus keeps just the right amount of salt and water in the amphibian. In some species the mucus is poisonous, which helps keep predators from eating the amphibian. SENSING THE WORLD Some amphibians have good eyesight and hearing, and some do not. Most frogs and toads can hear well. Salamanders, caecilians, and some frogs can only sense vibrations in the ground or water. Frogs have great eyesight. They see through two bulging eyes that stick out from their heads. Most caecilians are totally blind. All amphibians can smell and taste pretty well. Caecilians use feelers on their heads. Amphibians have a place in their mouths called Jacobson’s organ that helps them smell and taste the world
around them.

AN AMPHIBIAN’S LIFE
Amphibians that live in cold places spend most of their time trying to keep wet and warm. In hot places, they try to keep wet and cool and usually come out only at night. During the day, theystay under rocks or logs or in the ground. Amphibians hibernate (become inactive) during cold winters. They become inactive in hot places during the summer. Almost all grown-up amphibians are meat eaters. Frogs and salamanders have sticky tongues. They flick out their tongues to catch insects, spiders, and other animals. Caecilians have sharp teeth for grabbing their prey. Amphibians mate when it is rainy outside. They gather in groups tofind mates. Some male salamanders show bright colors to get the attention of females. Male frogs call out to females. Their call sounds like this: “ribbet.” Female amphibians lay eggs in water or wet places on land. Larvae hatch out of the eggs. No one knows how long amphibians live in thewild. Some capturedtoads have lived 30 years.

WHERE AMPHIBIANS LIVE
Amphibians live everywhere except Antarctica. They can be found in grasslands, rain forests, evergreen forests, deserts, and mountain areas. Caecilians live only in the tropics. Amphibiansneed water to breed and have babies. So most of themlive near ponds, swamps, or streams. A few species can even find water in deserts. Some burrowing frogs live in a dry part of
Australia called the outback. They breed and feed only when it rains, which is not very often.

DISAPPEARING AMPHIBIANS
Amphibians have lived on Earth for more than 300 million years. But recently, something scary has been happening to them. Amphibians are disappearing. There are fewer and fewer amphibians in many parts of the world, including North America, South America, and Australia. No one knows why. Some amphibians have also been found with extra legs or other strange problems. Scientists are working hard to find out what is happening to the amphibians.

Flags

Pieces of cloth in different colors, shapes, and patterns flap and snap in the breeze. They usually hang from poles or staffs. They stand as proud symbols for countries, states, persons, or groups. Sometimes, they are waved as a signal to people. What are these high-flying spectacles? Flags, of course!

NATIONAL FLAGS
The most important and best-known flags are national flags. A national flag stands for the people of a country. Every country has its own unique flag. The national flag of the United States is famous for its stars and stripes and colors of red, white, and blue. Most countries, including the United States and Canada, have a number of official flags. Some flags represent smaller areas of countries. Every state in the United States and every province in Canada has its own flag. Many cities have their own flags, too. Many countries create special flags for important government leaders. The U.S. president, vice president, and cabinet members all have unique flags.

MILITARY FLAGS
Most countries have special military flags. In the United States, different military units carry different flags. The U.S. Navy, Coast Guard, Army, Air Force, and Marine Corps all fly different flags. Navies fly flags on ships at sea. A national flag shows a ship’s nationality. Other flags are used for signaling, or sending messages, to other ships. Military units on land carry their own flags. Larger units, such as U.S. Army regiments, carry special flags, called colors. Smaller army units often fly their own flags, too. Hundreds of years ago, soldiers known as knights charged into battle beneath fluttering pennants. A pennant is a triangle-shaped flag. Today, many military units still carry pennants.

PERSONAL FLAGS
Long before there were national flags, kings and nobles flew their own flags. They decorated their flags with their family crest. The largest flag, called a standard, marked the presence of a king. Other nobles flew flags of different sizes and shapes based on their rank. As kings shaped their lands into nations, national flags grew in importance. Today, we recognize countries all around the world by their unique flags, called national standards. But most royal families still fly their own special flags.

Albert Einstein

Dents in space, light in bundles, and matter that turns into energy sound like science-fiction fantasies. However, Albert Einstein said they were real. Other scientists proved through observations that Einstein’s theories were right. Einstein revolutionized the science of physics and helped bring in the atomic age.

WHERE DID EINSTEIN GROW UP?
Albert Einstein was born in Ulm, Germany, on March 14, 1879. He grew up in Germany, Italy, and Switzerland. Einstein taught himself geometry when he was 12 years old. School bored him because it required endless memorizing and reciting. He often skipped classes to study on his own or to play his violin. Yet he graduated from college in 1900 and earned a Ph.D. degree in 1905. From 1902 to 1907, Einstein worked as a clerk in the patent office in Zürich, Switzerland. His job left him plenty of time to think.

WHAT DID EINSTEIN THINK ABOUT?
Einstein thought about the rules that govern the way the world works. For example, he explained why small particles in liquids wiggle around, a movement called Brownian motion. He said that the particles were being bumped into by tiny bits of matter called atoms that are too small to see. He also thought about light and electricity. Einstein knew that light shining on metal sometimes causes electricity to flow. He explained this result, called the photoelectric effect, by saying that light is made of tiny bundles of energy called photons. Photons hitting the metal knock particles called electrons away. Since electricity is simply moving electrons, he had solved the mystery of the photoelectric effect. In 1921, Einstein won the most famous prize in science, the Nobel Prize, for this work. Another thing Einstein thought about was time. He said that time does not always flow at the same rate. He proposed that motion affects time. He calledthis idea the special theory of relativity. Einstein then came up with his general theory of relativity. This theory has a new explanation for gravity. Einstein said that gravity comes from curves or dents in the fabric of space. Objects make dents in space the way a bowling ball makes a dent in a mattress. The Moon falls into the dent made by Earth and rolls around the Earth. Scientists later proved that the dent a star makes in space-time bends light as the light passes by. Einstein changed physics by showing that new ideas could come just from thinking. Before Einstein, most new ideas in physics had come from experiments in the laboratory.

EINSTEIN AND ATOMIC ENERGY
Einstein also said that matter and energy are the same thing. He expressed this relation in a famous equation: E=mc2. This equation says that energy (E) equals mass (m) times the speed of light squared (c2). Energy can therefore be changed into matter, and matter into energy. The ability to turn matter into energy led to the development of the atomic bomb and nuclear power.

FAME AND LATER YEARS
Einstein’s theories made him famous, even though few people understood them. He became a university professor and director of a physics institute in Berlin, Germany. After the Nazis rose to power in Germany, Einstein left. In 1933, he came to the United States, where he lived the rest of his life. Einstein died in Princeton, New Jersey, on April 18, 1955. Einstein’s last great idea was that every force in nature is part of one master force. Physicists are still working on this idea, which they call the theory of everything.

Leonardo da Vinci

Leonardo da Vinci excelled as a painter, sculptor, architect, engineer, and scientist. He had endless curiosity. Leonardo wanted to understand how things worked. He wanted to put down on paper what he saw. He left thousands of pages of drawings and notes that recorded his thoughts.

GOOD AT EVERYTHING
Leonardo was born in 1452 in the small town of Vinci, near Florence, Italy. He had little schooling and was largely self-taught. Leonardo seemed to be good at everything he tried. He was handsome, a good speaker, and a fine musician. He trained as a painter with Andrea del Verrocchio, a leading artist in Florence. Leonardo later worked for dukes and kings.

HIS MOST FAMOUS PAINTINGS
Leonardo produced a relatively small number of paintings, and he left some of them unfinished. But he had original ideas that influenced Italian artists long after his death. Leonardo believed painting was a science. He applied scientific thinking in his art so that his paintings looked more like the real world. One of his most important painting techniques was sfumato, a blending of one area of color into another so there are no sharp outlines. Leonardo used sfumato in one of his most famous paintings, the Mona Lisa. When you look at this portrait, notice how colors shade into each other on her face and hands. See how Leonardo has blurred the edges of her mouth to give her the hint of a smile. This mysterious smile has fascinated people for centuries. It looks as if Mona Lisa’s expression might change at any moment because of the way Leonardo has softened the edges of the mouth, eyes, and cheeks. She seems almost alive. Many people consider a mural by Leonardo known as The Last Supper to be his masterpiece. Christ, seated in the middle of The Last Supper, has just announced that one of his 12 apostles will betray him. Leonardo places the figures in this painting in a way that increases the drama of the announcement. Christ is the calm center. His body, which is set slightly apart from the others, forms a stable triangle. The apostles are arranged in four groups, some leaning toward Christ and some leaning away. Their gestures and the expressions on their faces reveal their reactions to Christ’s words.

HIS DRAWINGS AND NOTEBOOKS
Drawing was Leonardo’s favorite tool. He said that drawing was a better way of communicating ideas than words were. He drew catapults and war machines. He drew the muscles and skeletons of human beings and other animals. He drew clouds, swirling water, and storms. He designed churches that were never built. Leonardo’s drawings and theories are contained in numerous notebooks. His ideas were far in advance of what other people were thinking at the time. But the notebooks were not published during his lifetime. Had his notebooks been published, they might have revolutionized scientific thinking in the 1500s. Leonardo’s deep love of research was the key to both his artistic and scientific endeavors. Leonardo died in 1519.

Cold War

People once thought the Cold War would never end. Sometimes they feared nuclear bombs would blow up the world. Now the Cold War has faded to a distant memory. The Cold War was a conflict primarily between the United States and the Soviet Union. Each power brought other countries into the conflict on its side. The Cold War lasted more than 40 years, from the mid-1940s to the end of the 1980s. Why was the war “cold”? Because the United States and the Soviet Union never got into armed combat—a shooting or “hot” war—with each other.

HOW DID THE COLD WAR BEGIN?
The Cold War began soon after World War II ended in 1945. The United States and the Soviet Union had been allies (friends) in defeating Nazi Germany in that war. The Soviet army had invaded Germany from the east. After the war, the Soviet Union kept control of countries in Eastern Europe that it had freed from German control. Those countries included Bulgaria, Czechoslovakia, Hungary, Poland, and Romania. An iron curtain fell across Europe. That’s how Winston Churchill, Britain’s leader during World War II, described the division of Europe. There was no actual curtain, but there were strong barriers between Soviet-controlled Eastern Europe and largely democratic Western Europe. The Soviet Union insisted on that. Barbed wire and armed soldiers at borders kept Eastern Europe separate from Western Europe during the Cold War. Defeated Germany was split into East Germany under Soviet control, and West Germany. Berlin, Germany’s former capital, was a divided city. In 1961, a concrete wall went up in Berlin, along the dividing line. Broken glass on top of the Berlin Wall kept people from going over it and escaping to West Germany.

WHAT WAS THE CONFLICT ABOUT?
During the Cold War, the Soviet Union and the United States had different political and economic systems. The Soviet system was called communism. The United States and its allies feared that the Soviet Union wanted to spread communism to the rest of the world. They disliked this system. The goal of communism was to end private ownership of property. Under communism, the people would own everything communally (jointly). They would make decisions as a group. But things didn’t work out that way in the Soviet Union. Instead, the country became a dictatorship under the control of the Communist Party. Many freedoms were lost. Millions of people who disagreed with the Communist Party were arrested and sent to prison camps. The United States and most of the countries of Western Europe haddemocratic governments rather than dictatorships. They valued freedoms that had been lost in the Soviet Union. Their economic system—capitalism—was based on private ownership and on individual rather than group effort. At times during the Cold War, the United States lost some freedoms because of fear of communism. During the 1950s, many Americans who were suspected of sympathy for communism lost their jobs.

WHAT WAS THE ARMS RACE?
During the Cold War, each side built up its arsenal of weapons, especially nuclear weapons—atomic bombs and hydrogen bombs. These weapons could destroy cities and kill hundreds of thousands of people. Each side was afraid the other would start a nuclear war first. A nuclear arms race began. Each side said it needed more weapons to retaliate (fight back)in case of a nuclear attack. Both sides believed that if they had enough weapons the other side wouldn't dare start a nuclear war. If it did, it would face total destruction in retaliation.

HOW DID THE COLD WAR SPREAD?
The Soviet Union had put Communist governments in power in Eastern Europe. Communist leaders had come to power in China. The Soviet Union and China backed groups that tried to take power in other countries. Wars broke out. The United States entered wars to stop the spread of communism. With the Korean War (1950-1953), the Cold War reached Asia. China backed North Korea, and the United States supported South Korea. Korea was still divided when fighting stopped in 1953, and it remains divided today. In 1962, the Cold War brought the world to the edge of nuclear war. The United States discovered that the Soviet Union had installed nuclear missiles in Cuba. The missiles were pointed at the United States. War seemed certain, but the Soviet Union backed down and removed the missiles.

The United States fought the spread of communism in the Vietnam War (1959-1975). The U.S. government feared that if one Asian country fell to communism, the rest of Asia would become communist as well. The war ended with a communist victory in Vietnam. But communism did not spread throughout Asia.

HOW DID THE COLD WAR END?
The Soviet Union nearly went broke as a result of the Cold War weapons race. The Soviet people had given up hope of a better life ahead. In the mid-1980s, a new leader came to power in the Soviet Union, Mikhail Gorbachev. Gorbachev was determined to improve life in his country. In the process, he helped bring the Cold War to an end. Gorbachev called for more freedom for his people. He and U.S. resident Ronald Reagan agreed to destroy many of the weapons their countries had built. Gorbachev encouraged change in Eastern Europe, and he said that Soviet troops would no longer keep communist governments in power there. One after another, the countries of Eastern Europe got rid of their communist leaders. In 1989, the Berlin Wall came down. Europe was no longer divided. Finally, parts of the Soviet Union declared their independence. The Cold War ended with the collapse of communism in Eastern Europe in 1989, and the breakup of the Soviet Union in 1991.

Architecture

We ask for a lot from our buildings. They have to keep out the rain, wind, rats, and bugs, not to mention our enemies. They need to store our stuff, keep us warm when it’s cold, and keep us cool when it’s too hot. We also like our buildings to be well constructed and beautiful. Architecture is the important art and science of making buildings. Architects are the bosses who design buildings and supervise their construction.

WHAT ARE BUILDINGS MADE OF?
Buildings once were made of whatever materials were available. Where forests grew, for example, people used wood. Where there were no trees, people used the earth itself. They dried mud in the sun to make bricks. In the far north, they used blocks of snow or ice. These materials aren’t long-lasting, however. Mud bricks wear away. Wooden buildings catch fire and burn down.
Stone won’t catch fire, and it can be expected to endure. Many kinds of stone, including marble and limestone, are good materials to build with. Steel is strong and lightweight. It lets architects build tall buildings, like skyscrapers. But deciding on what materials to use isn’t usually the first thing an architect thinks about. The architect needs to know the reason for the building. How will the building be used?

REASONS FOR BUILDINGS
Shelter is the most basic reason for building. Buildings shelter us at home, at work, and at play. All buildings must shelter us from rain, wind, sun, and cold. Buildings also provide security. Some of the world’s most permanent structures were built to defend against enemies. Castles had moats and drawbridges to keep enemies out, and high walls from which to pour down boiling oil on them. Some of the most impressive buildings provide places for worship. Temples, churches, and mosques must meet spiritual needs. The soaring heights of a Gothic cathedral, for example, inspire amazement and admiration. Some buildings are just for showing off. Kings and emperors insisted on grand palaces and castles. People with money have always demanded that architecture display their wealth. Today, large corporations, governments, and universities demonstrate their importance by putting up impressive buildings. Architects today design all kinds of buildings. Our way of life calls for office buildings, large apartment complexes, shopping centers, schools, hospitals, airports, and hotels.

LANDMARK ARCHITECTURE
We judge the beauty of architecture in various ways. Some buildings have been judged especially great. In the past, architects lavished attention on religious structures. Today, many of the most
exciting buildings are museums and houses. Many people think the Greek temples are the most beautiful shrines of all time. The Greeks put columns around the outside of their temples. One masterpiece is the Parthenon, a temple on a hilltop in Athens, Greece. We admire its simplicity, but the carvings on the temple were once painted bright colors. Saint Peter’s in Vatican City was a major project of the 1500s. With its dome by Michelangelo, Saint Peter’s influenced many state capitol buildings in the United States.

America’s most famous architect is Frank Lloyd Wright. A number of his buildings are national landmarks. Most famous are the Guggenheim Museum in New York City and Fallingwater, a house in Pennsylvania. The Guggenheim’s spiraling ramp provides a dramatic showcase for artwork. Fallingwater overlooks a stream and waterfall. Its terraces appear to project from the surrounding hillside. Frank Gehry designs buildings that combine many irregular shapes. His Guggenheim Museum in Bilbao, Spain, uses titanium metal to create a curving, lightweight surface that shimmers in sunlight.

Amazon River

A dense, green forest lines the riverbanks. Monkeys chatter in the trees. Off to the side, a big crocodile sticks its eyes and nose out of the water. This is what a boat trip on the Amazon River can be like. Be careful not to fall overboard! Fish called piranhas may be swimming near the boat. A group of piranhas can gobble up a large animal in minutes.

THE MIGHTY AMAZON
The Amazon is a long river in South America. The river starts in snow and tiny streams, high in the Andes Mountains in Peru. It flows east through Brazil. After 4,000 miles (6,400 kilometers), the Amazon empties into the Atlantic Ocean. Along its route, hundreds of streams and smaller rivers empty into the Amazon. As a result, the Amazon carries more water than any other river in the world. Although the Amazon is the largest river in the world, it is not the longest. Only the Nile River in Africa is longer than the Amazon.

The Amazon changes size through the year. It is biggest from January to June, when heavy rains fall in Brazil. During the rainy season, the river is more than 50 miles (80 kilometers) wide in some places. The Amazon dumps several million tons of mud, sand, and other sediment in the Atlantic Ocean every day. Much of this sediment has washed down from the Andes Mountains. It turns the Amazon a muddy yellowish color. The sediment changes the color of the Atlantic for about 200 miles (about 320 kilometers) from the mouth of the Amazon.

WHAT ANIMALS LIVE IN THE AMAZON?
The Amazon is home to many interesting animals. The piranha is an Amazon fish with a bad reputation. One species (kind) of piranha has powerful jaws and sharp teeth that can tear flesh from bones. However, most piranhas eat plants. Stingrays and electric eels live in the Amazon, too. Stingrays have poisonous stingers on their tails. Snakelike electric eels use their electricity to stun prey. Giant otters, river dolphins, and manatees are among the mammals found in the Amazon. Crocodiles called caimans and giant turtles also live in the river.

THE AMAZON RAIN FOREST
A vast tropical rain forest lies next to the Amazon River in Brazil and neighboring countries. More than seven times the size of Texas, it is the largest rain forest in the world. The Amazon rain forest is home to colorful scarlet macaws, stealthy jaguars, noisy howler monkeys, bloodsucking vampire bats, three-toed sloths, long-nosed tapirs, and powerful anaconda snakes.
Many useful plants grow in the Amazon rain forest. They provide food, building materials, rubber, medicines, and other products.