Any group of birds, goats, or sheep can be referred to as a flock, but each feathered breed has its own proper title. Hawks travel in casts, while it’s a bevy of quail, a host of sparrows, and a covey of partridges.
Swans move in herds, and peacocks in musters, while a flock of herons is called a siege. A group of geese is properly called a gaggle, but only When they’re on the ground. In the air they are a skein.
Glow-in-the-dark stickers, stars, toys, and clothes, all work by absorbing light and emitting it later. These items contain phosphors, substances such as zinc sulfide that radiate visible light after being energized by natural light. Phosphorescent materials continue to glow after the energizing light is removed. They have electrons that are easily excited to higher energy levels when they absorb light energy.
In phosphorescent materials—such as glow-in-the-dark objects—the excited electrons drop to a lower, but still excited intermediate level and stay there for a period of time before returning to their ground state (original energy level) and emitting the excess energy as visible light.
The word fortnight is a unit of time that equals fourteen days. It comes from the Old English word feorwertyne niht, meaning “fourteen nights.” The term is used in Great Britain, where salaries and most social security benefits are paid on a fortnightly basis, but in the United States people use the term “two weeks.”
In many languages, there is no single word for a two-week period and the equivalent of “fourteen days” has to be used. In Spanish, Italian, French, and Portuguese, the terms quince días, quindicina, quinzaine, and quinzena—all meaning “fifteen days”—are used.
Babies grow in their mother’s uterus, a special organ that houses the baby until it is born. At the start of pregnancy, a mother’s egg is fertilized, which makes a new cell. The cell divides quickly into many more cells. At about one week, this tiny mass, called an embryo, sticks to the wall of the uterus, and begins to grow. From the moment of conception, 46 chromosomes and tens of thousands of genes combine to determine a baby’s physical characteristics—the sex, facial features, body type, and color of hair, eyes, and skin. At the eighth week, the embryo is called a fetus.
By the end of the twelfth week, the fetus is completely formed and is able to make a fist, can turn his or her head, and can squint and frown. Until the baby is ready to come out, it grows inside its mother’s uterus. When the baby is ready to be born, at about 40 weeks, the mother starts to feel labor contractions. The uterus squeezes and pushes the baby out of the uterus and into the world.
Earth Day is a national holiday that was first celebrated on April 22, 1970. It was created by Senator Gaylord Nelson, a Democrat from Wisconsin who was elected to the U.S. Senate in 1962. Senator Nelson decided to set aside one day aside for the entire nation to focus on environmental issues, learn about ways to improve the environment, and protest against the federal government’s unwillingness to help solve problems such as air pollution and the widespread destruction of forests.
After lots of hard work and publicity, on the first Earth Day 20 million Americans gathered at different places from the East to West coasts to hear speeches, participate in community-wide cleanup efforts, and demonstrate to the government that the environment is a major national issue. Ever since then, April 22 has been the date for celebrating Earth Day—a time when the United States (and now many countries all over the world) could participate in educational activities that celebrate Earth and think of new ways to preserve our natural resources. On Earth Day 2008, over 100 million people joined in the effort to celebrate and protect our planet.
Anteaters are slow-moving mammals with long snouts and claws and no teeth. If you can image it, a giant anteater can grow a tongue up to 2 feet (0.60 meters) long! The anteater uses its long tongue to investigate anthills in South America’s tropical dry forests, rain forests, and savannas.
It sticks its long, sticky tongue down the anthill, twirls it around, and scoops up a mouthful of ants. Anteaters can eat mouthful after mouthful of ants—up to 30,000 per day! It also eats termites and other insects.
Humans are credited with five senses: sight, hearing, touch, taste, and smell. So someone with a “sixth sense” is gifted with an unexplained perception outside of the common five.
The expression sixth sense comes from a study of blind people reported in 1903 in which it was found that, although deprived of sight, some of the subjects could perceive or sense certain objects in a room in a way that defied scientific understanding.
In a way, yes. Before the invention of refrigeration machines in 1805, people cut ice from ponds in winter and stored it in an icehouse. These icehouses were pits dug into the ground and lined with wood or straw and packed with snow and ice.
They were covered with an insulated roof. Because cold air sinks, the pit remained very cold, keeping foodstuffs cold and unspoiled until the early summer months.
The surface of a liquid is the seat of a special force as a result of which molecules on the surface are bound together to form something like a stretched membrane. They tend to compress the molecules below to the smallest possible volume, which causes the drop to take a round shape as for a given mass he sphere has minimum volume.
The Statue of Liberty stands for many of the nation’s most cherished ideals: freedom, equality, and democracy. Perhaps most importantly to the millions of immigrants for whom the statue was one of their first sights of the United States, it stands for the ideal of opportunity—the chance to begin a new life, in a new land. While their lives in the United States were frequently difficult, for millions of immigrants America offered the chance to escape from grinding poverty and abusive governments in other lands. Standing in the midst of New York Harbor, the point of entry into the United States for so many immigrants arriving on ships from other countries, the Statue of Liberty has been a powerful symbol of opportunity for more than 100 years.
A poem called “The New Colossus,” written by Emma Lazarus, was mounted on the statue’s pedestal in the early 1900s. Its famous lines include these words that Lazarus imagined Lady Liberty to be saying: Give me your tired, your poor, Your huddled masses yearning to breathe free, The wretched refuse of your teeming shore; Send these, the homeless, tempest-tost to me, I lift my lamp beside the golden door!