Actors have entertained audiences for thousands of years. In the past, plays were performed both to entertain and to teach. Today, plays involve the use of lighting, sound systems, and elaborate sets and often have large casts that include many actors.
For over two hundred years, individuals have protected and served their communities as lawmen. Today, people who help enforce the law are called police officers because both men and women can serve in the police force.
The first teachers in the United States were students who did well in school and were hired to teach other students. Today, teachers must have college degrees to teach. Schools today are larger than those in the past and often have several separate classes at the same grade level.
Batter up and explore the comprehensive history of America's favorite pastimeâ€”baseball! This fun book features baseball's timeline, which follows the evolution of the baseball official rules through time. Also addressed are the first African American and Women's baseball leagues. Photos will keep readers engaged and vocabulary related to the game and its history is provided.
Doctors help people stay healthy. When people get sick, doctors help them get well again. Today, doctors use many complex instruments to treat people. Long ago, doctors had few instruments and did not know as many ways to help people get well.
Some of the first geologists came from ancient Greece and Egypt. Later, scientists in China studied how land was formed and figured out how erosion wears away mountains, rocks, and other landforms. Scottish scientist James Hutton's The Theory of the Earth became the basis for modern geology. William Smith started out as a farmer, but went on to create what is thought to be the first geologic map. German Friedrick Mohs studied minerals and came up with a hardness identification scale that is still used by every geologist.
Maps and globes are among the most important tools that scientists have for studying the earth. In the 1500s, Gerardus Mercator created the first globes and maps. William Davis helped make geography a school subject and is a founder of geomorphology, the study of landforms. He also made important discoveries about the cycle of erosion. Many of today's discoveries come from photos taken from satellites that orbit our planet.
Ancient astronomers looked at movements in the sun, moon, and stars to guide travelers and keep track of the seasons. Nicholas Copernicus was the first to challenge people's beliefs that Earth was the center of the solar system and is known as the founder of astronomy. Galileo Galilei built a telescope and spotted craters on the moon and sunspots on the sun. Isaac Newton invented the reflecting telescope and discovered the law of gravity. Astronomers continue to work every day to uncover the mysteries of the universe.
Planck studied physics, the science of matter and energy. He wound up making big discoveries in the area of thermodynamics, which is the study of heat and how it moves. Planck won the Nobel Prize for his work in Quantum Physics, which is the movement inside of atoms. It changed the way scientists understood the world.
Marie Curie's work in radioactivity changed the way scientists think about matter and energy and led to advancements in the treatment of disease. With her fellow scientist and husband, Pierre Curie, she searched for the source of radioactivity and discovered two elements, radium and polonium. They shared the 1903 Nobel Prize, the world's highest science award, for their discovery.
Albert Einstein is probably the most influential scientist and greatest physicist of the twentieth century. He revolutionized our ideas about time and space and is best known for his theory of relativity and his equation E=mc^2, which explains the relationship between energy and mass. By age 30, he was considered by many to be one of the world's greatest scientific thinkers.
Isaac Newton is considered one of the greatest scientists who ever lived. His work changed the way humans understand astronomy, physics, math, and more. He is probably most famous for three laws about the way things move, called Newton's Law of Motion.
Scientists who have studied light and sound over the last few centuries invented many things that we still use today. Thomas Young, for example, proved that light moves in waves and invented prescription eyeglasses. The study of sound has led to inventions like the telephone and hearing aids. Thomas Edison studied both light and sound and invented such things as a long-lasting light bulb, the phonograph, and the first recording machine.
George Washington Carver was born a slave, but he became an important scientist and teacher. He experimented with soil and became famous for his work as a botanist. He used peanuts and other plants to make new products. Before Carver's research, plants were only used for food and clothing. His creative approach to agriculture taught people that plants could be used to make many products, like rubber, ink, fuel, and paper, to name a few.
Hippocrates was a Greek doctor who is called The Father of Medicine. Before he was born around 460 B.C., there was little science in medicine. Doctors thought the gods were to blame for illness. Hippocrates studied the human body and tried to figure out what caused disease so he could develop cures. Hippocrates suggested rules for doctors to follow. The Hippocratic Oath, which doctors still follow, was based on his teachings.