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Welcome to Britannica School, a safe, up-to-date, and age-appropriate information resource for Primary, Middle and Secondary School.

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BrainPOP - Animated Educational Site for Kids - Science, Social Studies, English, Math, Arts & Music, Health, and Technology

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How Do Your Body Parts Work? | Non Stop Episodes | The Dr. Binocs Show | PEEKABOO KIDZ

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A kingdom is a piece of land that is ruled by a king or a queen. A kingdom is often called a monarchy, which means that one person, usually inheriting their position by birth or marriage, is the leader, or head of state.

Kingdoms are one of the earliest types of societies on Earth, dating back thousands of years. There have been hundreds, if not thousands, of different kingdoms throughout history. Kingdoms can be huge, such as the United Kingdom. During the nineteenth century, the United Kingdom, ruled from London, England, stretched over five continents. Kingdoms can also be small, such as the kingdom of Brunei, which is smaller than the U.S. state of Delaware.

Kingdoms are rarely ruled by an absolute monarch, a single king or queen who makes all decisions for the entire state. Kingdoms are usually broken into smaller territories, such as city-states or provinces, that are governed by officials who report to the monarch. Most modern kings and queens do not control the government. Elected leaders and constitutions establish laws for most kingdoms today.
Early Kingdoms
The world's earliest kingdoms developed thousands of years ago when leaders began conquering and controlling cities and settlements. Rulers of early kingdoms provided protection to their residents, or subjects. In return, subjects paid taxes or services to the monarch. Kingdoms also had the power to create and enforce laws.

The first kingdoms were established about 3000 BCE in Sumer and Egypt. Sumer was a kingdom that existed between the Tigris and Euphrates Rivers in modern Iraq. The Sumerians had their own written language and undertook complicated construction projects, such as irrigation canals and large temples called ziggurats. There is also evidence that the Sumerian kingdom traded and fought with neighboring peoples.

A few thousand years later, the kingdom of Teotihuacan developed in North America. The kingdom was centered in the city of Teotihuacan in modern Mexico City, Mexico. Teotihuacan probably had more than 100,000 inhabitants, making it among the largest ancient kingdoms in the world at that time.

Many, but not all, ancient kingdoms were empires. Empires are geographically large political units made of many different cultural or ethnic groups. Empires were often headed by monarchs, making them kingdoms. The ancient Egyptian empire was a kingdom ruled by a monarch called a pharaoh, for instance. The Egyptian empire reached its height in the so-called "New Kingdom" period, under the leadership of the pharaoh Amenhotep III (1390-1352 BCE). Egypt in the New Kingdom stretched from modern-day Egypt, along the Mediterranean coast to modern-day Turkey in the north, and modern-day Eritrea in the south.

Many empires did not have monarchs, however, so empire and kingdom are not always the same thing.
Medieval Kingdoms
The Middle Ages was a period in history that lasted roughly from about 500 to 1500. It is also referred to as the medieval period. During the Middle Ages, countless kingdoms formed and collapsed throughout Europe, Asia, and Africa.

In Europe, many small kingdoms were formed and fought over by tribes following the collapse of the Roman Empire in 476. Tribes such as the Ostrogoths, from modern Romania, and the Franks, from modern Germany, were among those that formed small, unstable kingdoms in the early Middle Ages.

Perhaps the most famous European kingdom of the Middle Ages was that of Britain's legendary King Arthur. Arthur may not have existed at all. Accounts of his kingdom were written hundreds of years after it supposedly existed. If there was a King Arthur, he probably lived during the fifth century, after the Romans left Britain and before the emergence of actual, historical British kings in the eighth century. King Arthur would have been one of dozens, or perhaps hundreds, of kings in Britain at the time. Even if King Arthur did not exist, his legend suggests kingdoms played a role in the Middle Ages.

At around the same time tribes and small kingdoms were warring over parts of Europe, the African kingdoms of Ghana and Mali were among the strongest of the Middle Ages. The Ghana Empire, also known as the Wagadou Empire, formed about 790. It found success as a major trading center. The Ghana Empire, located in the modern countries of Mauritania and Mali, was a kingdom on the southwest edge of the Sahara Desert. Caravans with hundreds of camels would travel across the Sahara like ships crossing a sandy sea.

The kingdom emerged as a trading center for gold and salt. (Salt, a valuable preservative for food, was nearly as valuable as gold.) The trade of ideas also flourished in the kingdom, as the religion of Islam spread westward from the Arabian Peninsula to the western coast of Africa. The Ghana Empire was weakened and eventually collapsed because of rapid growth, drought, and weakened trade.

About 1200, the Mali Empire rose out of what was once Ghana. Mali became a strong kingdom under the leadership of King Sundiata. Sundiata's kingdom stretched from the Atlantic coast of the modern countries of Senegal and Mauritania to the inland area of southeast Mali. Like Ghana, the Mali Empire depended on trade routes through the Sahara. Unlike Ghana, this kingdom actually had its own gold mines within its borders. One of the kingdom's major cities was the trade hub of Timbuktu, in the modern nation of Mali. Timbuktu was the major trade city on the edge of the Sahara for hundreds of years, trading gold, ivory, salt, and slaves.
Later Kingdoms
After many centuries of war and turmoil, stronger and more sophisticated kingdoms began to develop throughout the world. In Europe, the kingdoms of Portugal, France, and England expanded across vast territories after the discovery of the Americas in the late fifteenth century.

Kingdoms established stronger diplomatic ties with neighboring governments to reduce conflict. They relied on treaties and, often, marriages to create strong alliances. Many monarchs of Europe during this period were related to each other. The British Queen Victoria had many grandchildren which were married to people across Europe, a fact that may have contributed to mostly peaceful times during her reign.

Kingdoms of this period increased trade with far-away kingdoms and built strong fleets for overseas exploration. The Portuguese Empire, for instance, established ties with the Kingdom of Siam, in the modern country of Thailand. Portugal's fleet was able to travel around the continent of Africa and along the coast of Asia to reach Siam. Portugal, which dominated trade routes in the Indian Ocean, traded for valuable spices.

The Kingdom of Siam was exposed to European technology and politics. While some Asian kingdoms, such as Japan, rejected the influence of European powers, Siam used European ideas to modernize the country. Siam reached its peak under King Mongkut, who ruled from 1851-1868. King Mongkut helped establish the first newspaper in the kingdom. King Mongkut also introduced the idea of free trade. Subjects in the kingdom could manufacture their own trade goods, such as rice or tea, for trade with foreign businesses.
Modern Kingdoms
A few kingdoms are still ruled absolutely by a monarch. King Salman bin Abdulaziz Al Saud of Saudi Arabia, King Mswati III of Swaziland, and King Hassanal Bolkiah of Brunei are absolute monarchs. All of these kingdoms have legislatures and sets of laws. The monarch remains the final authority.

However, most of the kingdoms that exist today are constitutional monarchies. The king or queen acts as a ceremonial head of state, with public responsibilities such as promoting tourism and interest in the nation's history and culture but no real political authority. Under a constitutional monarchy, the nation is governed by a constitution, or set of laws, executed by a president or prime minister elected by the country's citizens. In England, for example, Queen Elizabeth II is the official head of state-but the nation is governed by a prime minister and parliament.

The Kingdom of Thailand, formerly the Kingdom of Siam, is an example of a modern kingdom. The kingdom ended its absolute monarchy in 1932, and today it is a democracy with elected leaders and courts of law. However, the king of Thailand, Maha Vajiralongkorn, has reigned since 2016 after the death of his father Bhumibol Adulyadej, who was the longest-serving king in Thai history. King Adulyadej had tremendous public support and had been known to intervene in politics. His son seems to be less popular and his role somewhat uncertain.

Other modern kingdoms ruled by a constitutional monarchy include Sweden, Belgium, Japan, and Morocco.

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A kingdom is a piece of land that is ruled by a king or a queen. A kingdom is often called a monarchy, which means that one person, usually inheriting their position by birth or marriage, is the leader, or head of state.

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Bourbon Kings of France 1589-1830 minus some years during French Revolution

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Bourbon Kings of France 1589-1830 minus some years during French Revolution

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We believe you’ll find that today’s Wonder of the Day is good for the sole!

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The KidsHealth parents site offers advice on children’s health, behavior, and growth —from before birth through the teen years.

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Look at the "What Comedians Do" section of this article

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Look at the "What Comedians Do" section of this article

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Why doesn't glue stick to the inside of the bottle?

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Why doesn't glue stick to the inside of the bottle?

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Ever wonder what makes super glue so super? The little tube of super glue in your is really a type of with a big name: cyanoacrylate .

Epoxies and resins are types of adhesives. When these adhesives are mixed, a occurs, causing them to harden.

Cyanoacrylate is an that forms its strongest almost instantly. The only thing it requires to set is water. Since almost every object has at least tiny amounts of water on its , super glue does a super job of sticking most things together very quickly.

Even the air contains water in the form of humidity. As soon as cyanoacrylate molecules come into contact with water, they begin forming a sort of plastic .

As the glue hardens, the strands of the can no longer move, strengthening the . If the glue cannot absorb enough water from the air, the bonding process cannot begin and the glue will not harden.

The warnings on super glue are no joke. Super glue can't tell the difference between an art project and human fingers, and it sticks them together all the same.

Skin is made up of all sorts of cracks, crevices, grooves, and pores that give the glue a perfect to grab onto. In addition, skin is with water, which activates the glue's hardening process.

Incredibly, doctors have found medical uses for special types of glues. You won't find these glues on hardware store shelves, but medical adhesives are sometimes used to close wounds instead of using traditional or staples.

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Ever wonder what makes super glue so super? The little tube of super glue in your is really a type of with a big name: cyanoacrylate . Epoxies and resins are types of adhesives. When these adhesives are mixed, a occurs, causing them to harden. Cyanoacrylate is an that forms its strongest almost instantly.

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Hybrid Car

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Although many crystals may look alike at first glance, in this experiment we find a couple of ways to tell them apart.

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The Secret Science of Glue - American Chemical Society

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How strong can glue be? What’s tape made from? Find the answers to these sticky questions and many more!

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Sniffing glue is a cheap, but dangerous way people have used to get high for many years. Solvent glue is one of many common substances that fall under the category of "inhalants." Others include:

Common forms of solvent glues include model glue and rubber cement.

Inhalants are typically used by adolescents as a cheaper and more easily accessible alternative to marijuana and other drugs. The National Institute on Drug Abuse notes that inhalants are the only class of substances used more by younger teens than older teens.

Sniffing glue can be life-threatening. Even if the result isn't fatal, the risks associated with glue and other inhalants include possible brain damage and severe breathing problems.

Your experience with sniffing glue may be much different than another person's. In addition, the effect of one glue-sniffing attempt could be more or less severe than earlier or subsequent experiences.

The following includes some of the more serious risks and dangers of sniffing glue.

Acute respiratory failure

Acute respiratory failure is a potentially fatal condition that can occur when something impairs your ability to breathe or directly affects your lungs. This prevents a sufficient amount of oxygen from reaching the rest of the body.

The use of glue and other inhalants, as well as excessive alcohol consumption, are all possible causes of acute respiratory failure. Ongoing drug and alcohol abuse, as well other lung problems can also lead to chronic respiratory failure, a condition in which the body can't take in enough oxygen over time. In serious cases, chronic respiratory failure can lead to coma.

Brain damage

Sniffing glue and other inhalants - especially those that include the solvents toluene and naphthalene - can damage the myelin sheath, the thin covering around the nerve fibers in the brain and the rest of your nervous system. This damage can cause long-term harm to brain function, causing neurological problems similar to those seen with multiple sclerosis.

Heart rhythm disturbances

Exposure to the chemicals in glue can lead to an irregular heartbeat ( arrhythmia). In some cases, the abnormal rhythms can lead to fatal heart failure. This is known as sudden sniffing death syndrome (SSDS), and it can occur from just one attempt.

Other serious health risks associated with sniffing glue include:

liver damage

kidney damage

choking (often from vomit)

injuries resulting from impaired judgment, such as falls or car accidents

In addition to serious health complications, there are also short-term symptoms and consequences of sniffing glue. Among them are:

chemical odor on clothes and breath

glue-sniffer's rash - a rash around the mouth that extends to the middle of the face

headaches

dizziness

nausea and vomiting

abdominal pain

mood swings and belligerence

appearing intoxicated

decline in thinking skills, concentration, and decision-making ability

loss of interest in normal activities

damage to personal relationships

numbness

tingling in hands and feet

loss of coordination

fatigue

hearing loss

apathy

impaired judgment

loss of consciousness

The "high" you can get from sniffing glue or inhaling other chemicals may cause a temporary sense of euphoria or hallucinations. However, these feelings only last a few minutes and aren't worth the risks to your health.

Inhaling glue and other chemicals is dangerous and should never be attempted.

If you or your child is sniffing glue and may be addicted to the practice, formal addiction treatment may be helpful.

Physical examination

Treatment usually starts with a thorough physical examination, checking for:

brain and central nervous system damage

heart rhythm disturbances

liver damage

kidney damage

lung problems

The chemicals in glue and other inhalants can stay in the body's fatty tissues for weeks, meaning there may be residual effects long after a person's last experience with the substances.

Neurological testing

Neurological testing is also critical in planning a treatment program. Doctors will need to see if there are any permanent injuries to brain function and memory. A person's mental and emotional health will also need evaluation by a trained therapist.

Therapy sessions

If the person sniffing glue is a student, treatment may include therapy designed to help them deal with peer pressure and find a peer group that will provide a more positive influence.

Avoidance of inhalants and other drugs is a primary goal of treatment. Young people in treatment also learn basic life skills to help them focus on their future and make healthy decisions.

Therapy sessions may include group work, as well as music and art. Recreational activities that involve physical action and multisensory stimuli can be especially helpful. Other forms of treatment may include individual talk therapy, peer support groups, family therapy, and relapse prevention education.

Talk therapy may take the form of cognitive behavioral therapy (CBT). CBT helps you think differently about situations (such as understanding the reasons why you're turning to inhalants or other drugs), so that your feelings about those situations and your behaviors will change.

An inhalant user's attention span may be limited, especially early on in therapy. For that reason, therapy sessions may be limited to 15 or 30 minutes at a time. Expect a rehabilitation program to last longer than one month, partly because the chemicals can remain in the body for long periods.

Sniffing glue, huffing, and other types of inhalant use can cause short-term and long-term health problems, and even death.

If you're curious about the effects of glue sniffing, talk to a doctor, your parents, or a school counselor. You may benefit from exploring the reasons for your curiosity.

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Sniffing Glue: Serious Health Risks and Side Effects

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Sniffing glue is one of the more dangerous forms of getting a high, with several life-threatening side effects and many short- and long-term health consequences. Find out how sniffing glue affects your brain and the rest of your body. We'll also review treatment that can help you recover from an inhalant addiction.

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It's difficult to concentrate on your homework when your is rumbling, isn't it? If you're going to perform to your , you need to your with some healthy after-school snacks. But what should you eat?

That leftover pizza in the refrigerator probably looks . Of course, a big bowl of ice cream would hit the spot, too. Ripping open that new bag of potato chips would also be very satisfying . Your parents probably wouldn't of any of those choices, though.

When it comes to healthy after-school snacks, there's one thing that's sure to your while also satisfying your tooth: fruit! Before you pick up your pen again, grab an apple or an orange.

Have you ever given much thought to where your fruit comes from? And, no, we don't mean the grocery store. We're talking about how these fruits are grown. They come from trees, right?

Fruits and trees do seem to go hand in hand. After all, oranges and apples do grow on trees. So do many other fruits, such as apricots, cherries, lemons, limes, coconuts, grapefruits, mangoes, nectarines, peaches, pears, persimmons, plums, and pomegranates, to name just a few!

But not all fruits grow on trees. Some grow on vines on the , while others might grow on small plants or bushes. Let's take a closer look at some fruits that you won't find growing on a .

Watermelons, for example, do not grow on trees. Given the size of these large melons, we can all be happy about that. Can you a watermelon falling out of a onto your head? Ouch! Instead, watermelons grow on vines on the .

Watermelons aren't the only fruits that grow on the on vines. Fruits that grow in a similar way include cantaloupes and honeydew melons. Grapes also grow on vines, but their vines tend to rather than stay on the .

There are also several fruits that grow on bushes rather than trees. Most berries fall into this . Examples of fruits that grow on bushes include blueberries, raspberries, and strawberries.

There's one fruit that sounds like it would surely grow on a : the pineapple. Pine is a type of , and apples grow on trees, so surely pineapples grow on trees, right? Nope! Pineapples grow on a plant close to the . The pineapple's name comes from the Spanish word "pina" (because it reminded people of a pine cone) and the English word "apple" (because of its taste).

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We hope to see you in Wonderopolis today as we tackle a subject that's both juicy and delicious!

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Discover the Bromeliad, including its habitat, ecological role, and why protecting this species supports healthy forests and resilient communities.

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When you think of fruit, you probably think of something sweet and juicy to eat. Apples, berries and oranges are all fruit. But scientists think of fruit as a part of a plant that contains seeds. The fruit might not be sweet. In fact, it might not be edible at all. But it's still a fruit.

Fruit is usually soft and juicy, but not always. Sometimes it's covered by a hard, protective shell. Think about a watermelon, for instance. It is soft and juicy on the inside, but the outside is tough. Walnuts and other nuts are technically a fruit even though they are very hard.

Fun Facts about Fruits for Kids

Think of all the fruits and vegetables you eat. Are any of the vegetables you eat really fruit? How about tomatoes, peppers or green beans? They all have seeds and are all fruit. Pumpkins, squash, and cucumbers are also fruit.

Vegetables are edible plant parts that don't contain seeds. Lettuce, carrots and celery don't contain seeds - at least not the parts that we eat. These plants will flower and produce seed, but we usually eat them before they do so.

Some fruit, such as pomegranates, have tough, leathery skins.

Raspberries and blackberries are called aggregate fruit. They are made up of hundreds of little fruits. Each one contains a seed.

Fruit Vocabulary

Learn More about What is a Fruit

Watch this fun video about fruits:

A video about vegetables that are actually fruits.

Fruit Q&A

Question: Do all fruit grow on the ground?

Answer: Many fruits grow on trees, including apples, peaches, plums, oranges and lemons. Some fruit grow on vines.

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Question: Are any types of fruit poisonous?

Answer: Many round berries are poisonous. They might even look like an edible berry. Never eat a berry unless a grown up tells you it is safe.

Enjoyed the Easy Science for Kids Website on What is a Fruit info? Take the FREE & fun What is a Fruit quiz and download FREE What is a Fruit worksheet for kids. For lengthy info click here.

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Fun Fruit Facts for Kids (All You Need to Know!)

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Easy Science for Kids All About What is a Fruit, its Types and Characteristics. Learn more fun facts about Fruits with our Science Kids Website about Fruits

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Website Under Redevelopment - business enquiries: contact@blackboxmedia.au

Note: kidcyber.com.au is the name of the domain registrant's service that provides links to advertisements for services, goods, events or activities that may be of interest to you, based on the search term "kidcyber".

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Have you ever heard of Percy Jackson? How about Hercules? Medusa? If so, you might know that they're part of Greek mythology.

What is Greek mythology? It's a set of stories used by the ancient Greeks to understand the world. For the Greeks, mythology was tied to religion. Many experts believe that most Greeks thought the stories were true. Others think that Greek saw the stories as .

Have you ever WONDERed why the seasons change? How about why spiders weave webs? Do you know why the Sun moves across the sky? Science gives us answers to these questions today. But the ancient Greeks found these answers in their mythology.

The Greeks believed in many gods and goddesses. And, in their myths, the Greek gods and goddesses interacted with people often. They even acted like humans sometimes. They could be angry, vain, and jealous.

One of the best-known names from Greek mythology is Zeus. He was the king of the gods. After fighting the Titans, he ruled the world with his brothers and sisters. Their names were Hera, Hades, Poseidon, Hestia, and Demeter.

There are twelve major Greek gods and goddesses. They are called the Olympians. The Greeks explained many parts of nature with stories about the Olympians. The story of Hades, Persephone, and Demeter explained the changing seasons. The goddess Athena turned a weaver named Arachne into the first spider. Zeus's son, Apollo, pulled the Sun across the sky. Remember, the Greeks didn't have modern science. This is how they understood the world.

The Greeks also believed the Olympians ruled over different parts of the world. Zeus ruled the sky. Poseidon took charge of the sea. Hades ruled the Underworld. They believed Hera was the goddess of marriage and birth. Demeter ruled over the , and Hestia was the goddess of the home. Other gods and goddesses had their own jobs.

The Greeks also had many stories about heroes. They were often . That meant they had one human parent. Their other parent was a god or goddess. Famous Greek heroes include the Hercules, Theseus, and Achilles. They did great things, often with the help of the gods.

Sometimes, the Greek heroes had help from . One example was Pegasus. This was the flying horse often ridden by heroes and gods. More often, the meant the heroes . A few examples are the Minotaur, Medusa, and Hydra. Heroes had to prove themselves by fighting these .

Rome defeated Greece in 146 BCE. So how do people today know about Greek mythology? Many of the stories were told in ancient Greek texts. This includes Theogony, The Iliad, and The Odyssey. The Romans also took many characters and stories from the Greeks to make their own mythology. That's another way Greek mythology lived on.

Do you know any stories from Greek mythology? Many of them are still told today. Greek myths many modern books, TV shows, and movies. Read more about Greek mythology, and you may notice some familiar stories!

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Today's Wonder of the Day may have you saying, "This is all GREEK to me"!

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Chart comparing Greek gods to Roman gods

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Chart comparing Greek gods to Roman gods

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Although Greek Gods are arguably better known, Greek and Roman mythology often have the same Gods with different names because many Roman Gods are borrowed from Greek mythology, often with different traits. For example, Cupid is the Roman god of love and E

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The body of traditional tales concerning the gods, heroes, and rituals of the ancient Greeks.

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Check out these ghastly Greek myths from the time of the Ancient Greeks! Read on, if you dare...
Greek 'myths' (short for mythology) are a series of stories about the Gods and magical beings of Greece. We'll bet you've heard of some of the famous - and infamous! - characters already, such as Heracles, (the strongest man on Earth) Zeus, (the God of the sky and king of the gods) Pegasus (a flying horse) and Hades (the god of the underworld).

Find out more about the grand Greek myths, below!

Greek mythology

Created thousands of years ago, Greek myths were epic stories about , passed down over generations. They often feature heroic battles and terrible creatures, and taught the importance of bravery, intelligence, and right and wrong. They showed that even the gods, like mortal men, could be punished or rewarded for their actions. Details of the ancient tales have been found on everything from pottery to temples to stone statues!

Greek myths were a huge part of the religion in Ancient Greece, and offer a glimpse into the lives of the ancient people who told them. Check out five of these fascinating Greek myths below, and meet the people-eating, fire-breathing beasts and the heroes who battled them!

The Monster: Scylla and Charybdis
The Hero: Odysseus
The Battle: On both sides of a narrow stretch of sea, monsters lie in wait. On one side, Scylla thrashes around her six snakelike heads, ready to crunch on passing sailors. On the other, Charybdis creates a deadly whirlpool. No person has ever faced these beasts and escaped unharmed. Now the king, Odysseus, and his crew must pass them to get home. They edge around Charybdis' spiralling sea, saving the ship from being swallowed whole. But Scylla swoops down and gobbles up six men. "Row!" Odysseus shouts, leading the rest of the crew past Scylla and out of the deadly channel. Having survived the dreaded beasts, Odysseus and his men continue their journey.

Did you know we have a FREE downloadable Greek Mythology primary resource? Great for teachers, homeschoolers and parents alike!

Theseus and the Minotaur

The Monster: The Minotaur
The Hero: Theseus
The Battle: Half-man, half-bull, the Minotaur lurks in an underground maze waiting for his next meal - children sent to him as a sacrifice. Lost in the labyrinth, the kids surely will be devoured. But brave king Theseus has had enough of his land living in fear of the Minotaur. He accompanies the group and is prepared to fight. Hearing the Minotaur breathing nearby, he springs toward it. Dodging the monster's deadly horns, he thrusts his sword into the beast. The Minotaur is dead, but will the group find its way out? Luckily, Theseus unspooled a piece of string as he walked through the maze, and leads the children out to safety.

The Labours of Heracles

The Monster: The Hydra
The Hero: Heracles
The Battle: In a swamp creeps a deadly nine-headed serpent called the Hydra. Killing it is one of 12 tasks Heracles - the son of Greek god, Zeus - must complete to become immortal. After throwing flaming spears at the beast, the Hydra attacks so Heracles hits its heads with a club, but more grow in their place! Heracles' friend, Iolus, then leaps to his aid with a flaming torch. After an epic battle, the men finally destroy the Hydra!

Perseus and Medusa

The Monster: Medusa
The Hero: Perseus
The Battle: The hideous Medusa has snakes for hair, terrifying tusks and a face that turns anyone that looks at it into stone! To please his king, warrior Perseus agrees to slay the beast. Wearing a helmet of invisibility, he sneaks up on Medusa. She's asleep, but one gaze at her face and Perseus would be a statue! So he looks at her harmless reflection in his shiny shield and beheads her. Victorious, Perseus flies off on winged sandals.

Bellerophon and Pegasus

The Monster: The Chimera
The Hero: Bellerophon
The Battle: The fire-breathing Chimera is a terrifying beast with a serpent for a tail, a goat's body and a lion's head! A king has commanded warrior, Bellerophon, to destroy her. Soaring above the monster on a winged horse, Pegasus, he shoots arrows at her. Bellerophon then attaches lead to his spear and thrusts it into the vicious beast. The hero's actions kills the fiery Chimera.

Read more about amazing ancient adventures in National Geographic Treasury of Greek Mythology.

Did you know we have a FREE downloadable primary resource about the Lost City of Atlantis? Perfect for teachers, homeschoolers and parents alike, the resource investigates the legendary Ancient Greek island swallowed by the sea!

Illustrations: Ben Shannon

What do you make of our Greek myths? Let us know by leaving a comment, below!

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Ancient Greek Myths | National Geographic Kids

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Meet the monsters of Ancient Greek mythology here at Nat Geo Kids. We explore the tales of Medusa, the Minotaur, the Chimera and other Greek myths...

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Here's a project for you: place a black sheet of paper on a cookie sheet. Set the paper outdoors the next time it snows. Allow a few snowflakes to fall on the paper. Bring the cookie sheet indoors and look at the snowflakes through a magnifying lens. What do you see? That flat snowflake actually contains many tiny crystals.

Crystals are solid materials that have a highly ordered atomic structure. They are formed through a process called crystallization, where atoms or molecules arrange themselves in a repeating pattern. Crystals can be found in nature, such as quartz and diamond, or they can be artificially created. They have various uses, including in jewelry, electronics, and medicine, due to their unique properties like transparency, hardness, and ability to transmit and store energy.

Crystals Facts for Kids

Crystals form in nature over time.

They have regular shapes and patterns.

Diamonds and quartz are crystals.

They grow from a solution.

Some crystals can change color.

Salt and sugar also form crystals.

Each crystal has unique properties.

Crystals can be big or small.

Snowflakes are crystals.

Some crystals are used in electronics.

Salt crystals are cubic in shape.

Minerals

Children are naturally attracted to the marvel and beauty of crystals, which are a unique part of the natural world and encompass a special category within minerals. Crystals are solid, inorganic substances that occur naturally, formed by a precise pattern of interconnected molecules, resulting in a distinct shape for each crystal.

Examples of such minerals include salt, diamond, and quartz. The world's largest recorded crystals, the gypsum crystals, are found in Mexico's Cave of Crystals and can reach impressive lengths of up to 36 feet. Crystals, varying in color, size, and shape, are found globally.

Beyond their aesthetic appeal, crystals also hold practical significance, such as quartz used in watches and some believed to possess healing properties in alternative medicine.

Gemstones

Gemstones, a specific type of crystal, are incredible natural formations that originate from a variety of shapes, colors, and sizes. These gemstones often formed deep within the Earth over millions of years, are a result of atoms combining in specific patterns under extreme heat and pressure, creating these stunning structures.

Each gemstone, whether it's ruby, emerald, or diamond, possesses a unique formation pattern that enhances its color and sparkle. Beyond their aesthetic appeal often utilized in jewelry, these gemstones also serve functional purposes in daily essentials like watches and in specific industrial tools.

Crystallography

Crystallography, the scientific exploration of crystals and their unique structures should be understood as more than just the study of beautiful, shiny objects. Children, in particular, should be educated about the fascinating atomic structure of these crystals, each comprising a regular repeating pattern that forms a crystal lattice, contributing to their distinct shape and color.

Common crystals such as diamonds, emeralds, and everyday substances like salt and sugar are part of this vast domain. Hence, the next time a child sprinkles salt on their food, they should be reminded of the fact that they are utilizing minuscule crystals, thus instilling an appreciation for the science of crystallography.

Crystal formations

Crystals, captivating natural formations with diverse shapes and colors, manifest when a liquid solidifies upon cooling or water evaporates from a mineral solution. As these processes occur, the atoms or molecules composing the crystal arrange themselves repeatedly, shaping the crystal's distinctive structure.

Notable examples of these crystalline structures include quartz, diamonds, salt, and sugar, which may require thousands to millions of years to form. Consequently, every crystal encapsulates a small fragment of Earth's geological chronicle.

Crystal healing

Crystal healing, a fascinating concept embraced by many, suggests that specific crystals can enhance one's health or mood by interacting with their energy.

This is based on the belief that crystals, such as amethysts reputed to calm the mind and rose quartz known to foster love and peace, carry energy that can influence ours when they come into contact with our bodies. They can be positioned on various parts of the body or adorned as jewelry to exert their effects.

However, it's crucial for younger individuals to comprehend that while engaging with crystal healing can be an intriguing venture, it should never replace medical advice or treatment provided by healthcare professionals.

Crystal structures

Crystals, while aesthetically pleasing, are also scientifically intriguing due to their unique structures. These structures are formed by the orderly and repeated arrangement of atoms, ions, or molecules in various directions, creating distinct, often symmetrical shapes.

For instance, the cubic or isometric crystal structure is characterized by atoms configured in a cube-like pattern, while other crystal structures such as hexagonal, tetragonal, and orthorhombic are differentiated by the shape of their 'unit cell', the simplest repetitive unit in the crystal.

Minerals in nature often adopt these geometrically pleasing crystal structures. Therefore, a crystal is not merely a beautiful stone, but a remarkable exemplification of scientific marvel.

Quartz crystals

Quartz crystals, one of the most widespread minerals found in the Earth's crust, offer a captivating and educational subject for children to learn about due to their unique properties and worldwide occurrence. These crystals, which can display a spectrum of colors including clear, pink (Rose Quartz), black (Smoky Quartz), and purple (Amethyst), are formed through the combination of silicon and oxygen under specific conditions within the Earth's crust.

What sets quartz crystals apart and makes them highly valuable, not just for their aesthetic appeal but also for their practical application, is their ability to generate electricity when pressure is applied, a phenomenon known as piezoelectricity. This property is harnessed in an array of everyday technologies, from wristwatches and radios to computer chips, showcasing the significant role quartz plays in our daily lives.

Crystal growth

Crystal growth, an enlightening scientific experiment for children, occurs when a liquid solution containing substances like salt or sugar begins to cool and solidify. During this process, the atoms or molecules within the solution assemble in a distinct pattern, creating a unique crystalline structure.

The dimensions of these crystals largely depend on their growth duration, with the size increasing over time. Each substance, when crystallized, yields uniquely shaped and colored crystals - cube-shaped for salt, oblong for sugar, and triclinic and blue for copper sulfate.

This fascinating phenomenon not only introduces children to science but also cultivates patience, and imparts an appreciation for the aesthetics of nature.

Crystal lattice

Children often find the intriguing structures of crystals captivating, especially when learning about the idea of a crystal lattice.

A crystal lattice is the unique and symmetrical arrangement of atoms, ions, or molecules in any crystalline material, repeated in a 3D pattern extending in all directions throughout the entire crystal. This specific, repeating pattern is what gives a crystal its distinctive shape, resulting in unique forms of crystals such as salt, diamonds, and quartz.

The lattice structures, however, vary between different types of crystals, leading to a diverse range of crystal appearances.

Crystallographic symmetry

Crystals, known for their beauty, also possess an intriguing scientific aspect termed crystallographic symmetry, which pertains to the uniform and balanced distribution of atoms within the crystal structure.

Upon closely observing the minute constituents of a crystal, one would notice a repetitive pattern extending in all directions, similar to the symmetrical halves of a perfectly cut piece of paper. This symmetrical pattern, which remains unchanged even after rotation or inversion, contributes to the unique shapes and properties of crystals, indicating the fundamental role of internal symmetry in establishing their distinct physical attributes.

How do crystals form? Crystals occur in minerals and other chemical compounds, including sugar, salt and ice. In minerals, crystals are created when molten rock or dissolved minerals cool and become solid very slowly. The atoms in minerals cling to each other by electrical forces. As they stick together, they form three-dimensional patterns.
What Shapes Do Crystals Form?

Cubic crystals, which resembles a box and has 6, 8 or even 12 sides.

Hexagonal or trigonal crystals, which have six or three sides.

Monoclinic crystals, which looks a bit like a multi-faced box.

Orthorhombic crystals, which may look like two pyramids stuck together.

Tetragonal crystals, which resemble a cube, but have one elongated side.

Triclinic crystals, which may not be symmetrical.

Fun Facts About Crystals for Kids

Crystallography is the scientific study of crystals and their formation.

Gemstones, like rubies, emeralds and sapphires, are crystals. The elements they are made up of determine their color.

A unit cell is what they call the basic building block of a crystal. It is the smallest arrangement of atoms that shows the crystal structure.

The ions and atoms, or actually their charges, must equal zero. A crystal will not form if the positive and negative charges of its components are different.

Some of the largest natural crystals in the world are found in the Cave of Crystals in Naica, Chihuahua, Mexico.

The most common crystals you may be familiar with are table salt, snowflakes and pencil lead (graphite).

Crystals Vocabulary

1. Crystal: a geometric structure usually created through heating and cooling minerals and other compounds

2. Molten: a solid that has melted due to high heat

3. Atom: a basic unit of any element

All About Crystals Video for Kids

Here's a great video for kids on Crystals:

Crystal Q&A

Question: How do geodes form?

Answer: When water in the Earth becomes hot enough to dissolve minerals in the rocks, the minerals are carried in the water where it seeps into cracks and holes in the rocks. When it cools, cavities filled with sparkling crystals form. These are geodes.

Enjoyed the Easy Earth Science for Kids Website about Crystals info? Take the FREE & fun Crystals quiz and download FREE all about Crystals worksheet for kids. For lengthy info click here.

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Fun Crystal Facts for Kids (All You Need to Know!)

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All About Crystals - Earth Science Facts for Kids. Learn science fun facts all about Crystals through our Fun and FREE Easy Earth Science Website for Kids

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A solid figure that is made up of a repeating pattern of geometric shapes is known as a crystal. Crystals form when a liquid cools and hardens. During this crystallization process, molecules within the liquid pull together in a pattern. Some crystals, such as emeralds, form when magma cools very slowly.

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Learning about crystals involves both science and math. Kids can go outside for a nature hike or experiment with basic household items to learn about crystals once they have a basic understanding of what makes up a crystalline structure. To help with the study of crystals, you may need to have a magnifying glass or a child's microscope to get a better look at the structure.

What Are Crystals?

What Are Crystals?

Crystals represent nature's organization. When atoms come together in an organized manner with a repeating pattern, it's considered a crystal. This results in a substance with a flat outer surface that has a geometric pattern, explains "What's That Rock or Mineral? A Beginner's Guide." They can be found in a variety of shapes, including orthorhombic, tetragonal, isometric, monoclinic, hexagonal, cubic and triclinic. One example of a crystal structure is a snowflake. When viewed under a microscope each snowflake looks different, but they all resemble a star with six distinct points.

Finding Natural Crystals

Finding Natural Crystals

All minerals and ice - along with snowflakes - are crystalline structures. You can take the kids outside for a scavenger hunt to find these crystals in nature. Some common crystals you may find on a hike include quartz, which forms in several colors, including milky white and pink; olivine, which is green; and magnetite, which is black. Even if you can't identify the type of rock you find, by looking closely at its outer structure you can often determine whether it is a crystal. The surface will usually have obvious repeating geometric shapes. An exception would be minerals that have been in rivers or streams, where the current makes the surface of rocks smooth and rounded.

Making Your Own Crystals

Making Your Own Crystals

Evaporation creates many crystals, and this is something you illustrate in your own kitchen. To make a crystal at home, fill a glass jar with 3 cups of hot water. Mix in 3 tablespoons of borax to the hot water and stir until it has all dissolved. With pipe cleaners, make a shape such as a star and tie a 12-inch piece of yarn to the star. Put the star into the solution and let it sit for at least 24 hours. Leave the other end of the yarn dangling outside the jar. Within 24 hours, crystals will start to form on the pipe cleaner. The longer you leave it, the bigger the crystals will grow.

Making Crystal Shapes

Making Crystal Shapes

Another educational crystal lesson for kids is to build the basic shapes that form crystals. An easy way to do this is to use straws and tape. Cut the straws to various lengths. Then connect the pieces with tape to make 3-D shapes that form crystals, such as a hexagonal or isometric. If you make several 3-D shapes, you can then connect those to build your own crystal.

Cite This Article

MLA

Anders, Lynn. "Learning About Crystals For Kids" sciencing.com, https://www.sciencing.com/learning-crystals-kids-5255258/. 24 April 2017.

APA

Anders, Lynn. (2017, April 24). Learning About Crystals For Kids. sciencing.com. Retrieved from https://www.sciencing.com/learning-crystals-kids-5255258/

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Anders, Lynn. Learning About Crystals For Kids last modified March 24, 2022. https://www.sciencing.com/learning-crystals-kids-5255258/

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Learning About Crystals For Kids - Sciencing

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Learning about crystals involves both science and math. Kids can go outside for a nature hike or experiment with basic household items to learn about crystals once they have a basic understanding of what makes up a crystalline structure.

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Crystals are solids that form by a regular repeated pattern of molecules connecting together. In crystals, a collection of atoms, called the Unit Cell, is repeated in exactly the same arrangement over and over throughout the entire material.

Crystals have:

An orderly and symmetrical atomic structure and a definite chemical composition.

A definite external geometrical shape bounded by plane faces.

Physical (and optical) properties which vary with direction (except for the isometric minerals).

Only if a mineral is allowed to grow without interference from other minerals will it form crystals. Minerals "grow," or crystallize, from many types of solutions. They may precipitate from evaporating sea water or crystallize from magmas when lava cools. While growing, minerals may develop a distinct crystal form with smooth, flat planes called crystal faces. The geometric pattern of the crystal faces reflects the internal atomic arrangement of the crystal structure. This is one of the most important things about a mineral.

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All About Crystals Home All About Crystals All About […]

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Collecting Crystals and Meditation/Decoration Use of Crystals

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Collecting Crystals and Meditation/Decoration Use of Crystals

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Marine animals that live in the ocean habitat

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Marine animals that live in the ocean habitat

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Just how deep does the ocean go? Way further than you think. Tech Insider's animation puts the actual distance into perspective, showing a vast distance between the waves we see and the mysterious point we call Challenger Deep.

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Despite making up more than 70% of the Earth's surface, there is still much about the oceans that we do not know.

Exploring and studying them is critical to protect these valuable resources for future generations. Uncover why we need to protect the oceans, find out how to get involved and dive into cutting-edge research about life underwater.

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Around 95% of the Earth’s oceans are still unexplored - we know less about the deep sea than we do about space. Explore the power of the ocean.

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Just how deep does the ocean go? Way further than you think. Tech Insider's animation puts the actual distance into perspective, showing a vast distance between the waves we see and the mysterious point we call Challenger Deep.

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Deep Sea Strangers: Fascinating and bizarre creatures from the ocean’s depths

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Fish - info and online games. Learn about sharks, bony fish and more. Includes a fact of the day and a fascinating fact.

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Some animals that live in the ocean defy description. It's hard to tell if they're a plant, an animal or something else altogether. These animals include sponges, sea urchins, coral, star fish, jellyfish and sea anemones.

They don't look like most animals, but they don't look exactly like plants either. The jellyfish, for example, looks like a blob of jelly with long trailing tentacles. Coral are attached to the ocean floor. They're hard and knobby. They almost look like rocks, but they're not.

Fun Facts about Strange Undersea Creatures for Kids

Coral polyps are tiny animals related to sea anemones. They have a hard limestone skeleton that they attach to a rock or the ocean floor. This is the beginning of a coral reef. Once attached, the polyp starts making clones of itself and the coral grows. It joins other polyps to make huge reefs. Algae grows on the coral, which colors it. Coral reefs provide shelter for thousands of marine animals. Pollution threatens coral reefs.

Sea anemones have a foot that attaches to a rock or the ocean floor. They have stinging tentacles. When a fish touches one of the tentacles, barbs shoot into the fish. The barbs are venomous and paralyze the fish. The tentacles guide the fish to the animal's mouth. Lunch is served.

Jellyfish have lived on earth for millions of years. They were here before the dinosaurs. Jellyfish have a soft body that floats through the water. Food goes in a hole in their bodies. Poisonous tentacles paralyze prey. Some jellyfish are dangerous to humans. The Portuguese Man-of-War is said to be as venomous as a cobra. Even dead jellyfish sting.

Sponges are animals that live on the ocean floor in colonies. Their bodies have lots of holes and canals. Their skeletons are used as sponges for cleaning. Tarpon Springs, a little town in Florida, was built by Greek sponge fishermen. They still hunt for sponges today.

Strange Under Sea Creatures Vocabulary

Learn More All About Strange Undersea Creatures

Watch this mystical documentary video of the different and strange creatures of the ocean:

A video documentary of the secrets of the deep and the lives of strange undersea creatures.

Strange Undersea Creature Q&A

Question: What are sea urchins?

Answer: Sea urchins are small animals that are covered with spines. They live on rocks or the ocean floor and feed on bits of plants and animals. Many sea urchins have poisonous spines.

----------

Question: Do these animals have body parts like other animals?

Answer: Usually not. Jellyfish, for example, don't have a brain, heart or blood.

Enjoyed the Easy Science for Kids Website about Strange Undersea Creatures info? Take the FREE & fun Strange Undersea Creatures quiz and download FREE Strange Undersea Creatures worksheet for kids. For lengthy info click here.

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Easy Science for Kids Plants or Animals? Strange Undersea Creatures - learn fun facts about animals, the human body, our planet and much more. Fun free Plants or Animals? Strange Undersea Creatures activities!

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Water covers more than 75% of the Earth and 99% of that water is salt water. The marine biome is made up of salt water regions and includes estuaries, coral reefs, shores, and the open ocean.

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When you think of the things you to , what comes to mind? Food and water probably top your list. Clothing probably isn't far behind. There's one other basic that we sometimes take for granted: .

If you don't have a safe place to sleep at night, life can become very difficult in a hurry. Think of the struggle the homeless of the world experience nightly. Most of us are fortunate enough to have a over our heads.

The buildings we live in come in an almost-endless variety of types, shapes, and sizes. Some houses are small, some are large. Some houses are . Others might be skyscrapers that contain thousands of apartments.

When it comes to buildings, the number of different types of structures that around the world is mind-boggling. From grass huts in the tropics and igloos in the Arctic to skyscrapers in the big city and single-family homes in the suburbs, it seems like there's a building to suit every environment and purpose.

Curious children often WONDER about exactly how buildings are built. Given the great variety of buildings, there's no one way to build one. There are a few common elements that most buildings share, though, and the basic processes are often similar, differing only in , materials, and other factors.

The first step in building isn't to reach for a hammer and some nails. Instead, it involves reaching for a pen and paper. A professional called an architect or civil engineer usually gets the process going by designing a blueprint for the building, which ends up being a guide construction workers will use to know how to build the building.

Once a blueprint is completed, most buildings follow a rough series of steps that have been established over the years. These steps allow builders to construct buildings in a cost-effective and manner that conforms to building codes.

After the building site has been prepared by to ensure a flat surface to build upon, construction workers create a foundation that will serve as the building's support. As a general rule, the taller the building is, the deeper its foundation must be.

Once the foundation has been laid, the framework of the building can be built using a combination of wood and steel beams. Special attention must be given to the placement of the beams that will become the load-bearing walls.

The primary problem any builder faces is keeping a building upright. Most of any building consists of empty space. The force of gravity will pull upon all the other parts of a building. If a building isn't constructed properly, gravity will ultimately and pull it to the ground. Load-bearing walls ensure that the upper parts of a building are supported and can withstand the force of gravity.

After framing is complete, windows, doors, and a can be installed. With the building enclosed, installation of the things you can't see, such as electrical wires, plumbing pipes, heating and air conditioning ducts, and insulation , can take place.

Next comes drywall to form the walls of the house, enclosing all the hidden things just installed. With walls up, flooring can be laid, followed by painting and finishing all the remaining interior work, such as trim, electrical outlets, and plumbing fixtures.

If you talk to any construction worker, you'll learn that this is just a general overview of the building process. There are many other steps involved along the way. Constructing a building is a complex process that involves experts in a wide variety of fields. It also involves advanced science and technology in ways that it's hard to appreciate until you've experienced the construction process from start to finish.

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When you think of the things you to , what comes to mind? Food and water probably top your list. Clothing probably isn't far behind. There's one other basic that we sometimes take for granted: . If you don't have a safe place to sleep at night, life can become very difficult in a hurry.

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What's that? Up there in the ! Is it a bird? Or a plane? No! It's a skyscraper! Have you ever seen a skyscraper up close? If you live in big city, there's a good chance you've probably seen many skyscrapers. If you don't, however, you might have only seen skyscrapers on a vacation to a big city or simply on television.

Skyscraper is a very descriptive term for these buildings that way high up into the . From the ground looking up, they do seem to all the way up to the surface of the . If you ever get the chance to ride an all the way to the top floor of a skyscraper, you'll be rewarded with a magnificent view.

If you live in the United States, you know that there are some famous skyscrapers in Chicago and New York that have once held the of world's tallest . For example, the Empire State in New York City and the Willis Tower (formerly known as the Sears Tower) in Chicago have both held that in the past.

So where is the world's tallest today? As of January 4, 2010, the belongs to the Burj Khalifa in Dubai, United Arab Emirates. Standing more than a half-mile tall at an impressive 2,722 feet, the Burj Khalifa features a hotel, apartments, and corporate offices in its 163 floors.

Unfortunately for the Dubai , it might not retain that much longer. Saudi Arabia is already hard at work constructing the Kingdom Tower in Jeddah. When completed, it will the Burj Khalifa by more than 500 feet, rising a full kilometer to 3,280 feet!

Will buildings continue to get taller and taller into the future? It's possible. As science and technology continue to advance, architects will likely continue to push the when it comes to tall skyscrapers.

How tall can buildings go? No one knows for sure, but there are certain factors that tend to limit buildings from reaching a mile high or more. For starters, buildings must be designed to withstand the winds that exist at those heights.

Modern skyscrapers use a variety of technologies to battle the wind. Many modern skyscraper designs feature wind-resistant features that make them more aerodynamic . Even more impressive technologies exist in the tallest buildings. In Taiwan's Taipei 101 skyscraper, for example, a pendulum system in the top floors swings the opposite way of prevailing winds to prevent damage in the case of a .

Of course, money is also a concern. The advanced technologies required to build taller and taller buildings do not come cheap. taller buildings often comes at a tag that is simply too much to bear in the current economy. For example, the Burj Khalifa cost about $1.5 billion to build, which is on par with the recently constructed Dallas Cowboys football stadium.

Perhaps the biggest obstacle to even taller buildings, however, is the . Modern systems have just about reached their limit. When cables extend longer than 2,000 feet, they usually weigh too much to work properly. This means that some of the world's tallest buildings require " lobbies," where you have to transfer to another to take you to the highest floors.

Transferring to different elevators and slow speeds (to prevent discomfort from pressure changes) result in rides that are too long for some people. For example, reaching the top of the world's tallest buildings can take as long as three minutes or more without stopping at any other floors. As a result, until technology advances, we may only see minor advances in the height of the world's tallest buildings.

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Join us in Wonderopolis today for a Wonder of the Day that scrapes the sky!

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What's the Difference Between an Architect and an Engineer?

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Do you live in a big city? If so, you may be used to all the hustle and bustle and tall buildings. Many of our Wonder Friends live in small towns or rural areas, though. Is that you? If so, you may find a trip to a large city quite the change of pace.

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skyscraper, a very tall multistoried building. The name first came into use during the 1880s, shortly after the first skyscrapers were built, in the United States. The development of skyscrapers came as a result of the coincidence of several technological and social developments. The term skyscraper originally applied to buildings of 10 to 20 stories, but by the late 20th century the term was used to describe high-rise buildings of unusual height, generally greater than 40 or 50 stories.

The increase in urban commerce in the United States in the second half of the 19th century augmented the need for city business space, and the installation of the first safe passenger elevator (in the Haughwout Department Store, New York City) in 1857 made practical the erection of buildings more than four or five stories tall. Although the earliest skyscrapers rested on extremely thick masonry walls at the ground level, architects soon turned to the use of a cast- iron and wrought-iron framework to support the weight of the upper floors, allowing for more floor space on the lower stories. James Bogardus built the Cast Iron Building (1848, New York City) with a rigid frame of iron providing the main support for upper-floor and roof loads.

It was, however, the refinement of the Bessemer process, first used in the United States in the 1860s, that allowed for the major advance in skyscraper construction. As steel is stronger and lighter in weight than iron, the use of a steel frame made possible the construction of truly tall buildings. William Le Baron Jenney's 10-story Home Insurance Company Building (1884-85) in Chicago was the first to use steel-girder construction. Jenney's skyscrapers also first employed the curtain wall, an outer covering of masonry or other material that bears only its own weight and is affixed to and supported by the steel skeleton. Structurally, skyscrapers consist of a substructure of piers beneath the ground, a superstructure of columns and girders above the ground, and a curtain wall hung on the girders.

As the population density of urban areas has increased, so has the need for buildings that rise rather than spread. The skyscraper, which was originally a form of commercial architecture, has increasingly been used for residential purposes as well.

The design and decoration of skyscrapers have passed through several stages. Jenney and his protégé Louis Sullivan styled their buildings to accentuate verticality, with delineated columns rising from base to cornice. There was, however, some retention of, and regression to, earlier styles as well. As part of the Neoclassical revival, for instance, skyscrapers such as those designed by the firm of McKim, Mead, and White were modeled after Classical Greek columns. The Metropolitan Life Insurance Building in New York City (1909) was modeled by Napoleon Le Brun after the Campanile of St. Mark's in Venice, and the Woolworth Building (1913), by Cass Gilbert, is a prime example of neo-Gothic decoration. Even the Art Deco carvings on such towers as the Chrysler Building (1930), the Empire State Building (1931), and the RCA Building (1931) in New York City, which were then considered as modern as the new technology, are now viewed as more related to the old ornate decorations than to truly modern lines.

The International Style with its total simplicity seemed ideally suited to skyscraper design, and, during the decades following World War II, it dominated the field, notable early examples being the Seagram Building (1958) in New York City and the Lake Shore Drive Apartments (1951) in Chicago. The stark verticality and glass curtain walls of this style became a hallmark of ultramodern urban life in many countries. During the 1970s, however, attempts were made to redefine the human element in urban architecture. Zoning ordinances encouraged the incorporation of plazas and parks into and around the bases of even the tallest skyscrapers, just as zoning laws in the first decades of the 20th century were passed to prevent city streets from becoming sunless canyons and led to the shorter, stepped skyscraper. Office towers, such as those of the World Trade Center (1972) in New York City and the Sears Tower (1973; now called Willis Tower) in Chicago, continued to be built, but most of them, such as the Citicorp Center (1978) in New York City, featured lively and innovative space for shopping and entertainment at street level.

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Another factor influencing skyscraper design and construction in the late 20th and early 21st centuries was the need for energy conservation. Earlier, sealed windows that made necessary continuous forced-air circulation or cooling, for instance, gave way in mid-rise buildings to operable windows and glass walls that were tinted to reflect the sun's rays. Also, perhaps in reaction to the austerity of the International Style, the 1980s saw the beginnings of a return to more classical ornamentation, such as that of Philip Johnson's AT&T Building (1984) in New York City. See also high-rise building.

A listing of the world's tallest buildings is provided in the table.

rank

building

location

year completed

height* (metres)

height* (feet)

occupied floors

*To architectural top, as measured from the level of the lowest significant open-air pedestrian entrance to the topmost architectural feature of the building, including spires but not including antennas, signage, flag poles, or other functional or technical equipment.

Source: Council on Tall Buildings and Urban Habitat.

The Editors of Encyclopaedia Britannica Melissa Petruzzello.

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skyscraper | Definition, Building, History, & Facts

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skyscraper, a very tall multistoried building. The name first came into use during the 1880s, shortly after the first skyscrapers were built, in the United States. The development of skyscrapers came as a result of the coincidence of several technological and social developments.

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In 1956, architect Frank Lloyd Wright proposed a mile-high skyscraper, a building five times as high as the Eiffel Tower. While this massive tower was never built, today bigger and bigger buildings are going up around the world. How did these impossible ideas turn into architectural opportunities? Stefan Al explains how these megastructures became fixtures of our city skylines.

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Will there ever be a mile-high skyscraper? - Stefan Al

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In 1956, architect Frank Lloyd Wright proposed a mile-high skyscraper, a building five times as high as the Eiffel Tower. While this massive tower was never built, today bigger and bigger buildings are going up around the world. How did these impossible ideas turn into architectural opportunities?

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Many of our Wonder Friends know about Bastille Day. Others may have read about Napoleon Bonaparte. Maybe you've heard that Marie Antoinette said, "Let them eat cake!" These are all important parts of today's Wonder of the Day-the French Revolution.

The French Revolution is also known as the Revolution of 1789. That's because two more revolutions shook France in later years. However, the French Revolution didn't start in 1789. That's just when it reached its first . The war began in 1787.

What happened in 1787 to cause a revolution? As with any war, there was more than one cause. One was widespread . In the years before the revolution, France's population grew. But its rate of food production did not. That made food cost more. Many people couldn't feed their families.

France also had a large national . King Louis XVI wanted to raise taxes to help lower the . This angered many nobles. With so many unhappy with the government, things boiled over.

One of the biggest events of the French Revolution happened on July 14, 1789. That day, a stormed the Bastille. They freed the prisoners inside. They also took weapons to fight the king's forces.

Later in 1789, the National Assembly issued the Declaration on the Rights of Man. This gave French citizens freedom of speech, press, and religion. It also set up a . However, women and enslaved people were not citizens. They were not given these freedoms. They were also unable to vote.

Still, women and enslaved people helped the revolution. In October 1789, women in Paris led the March on Versailles. This was a protest against the rising cost of bread. Later, in 1794, revolutionary France made slavery illegal.

In June 1791, France's royal family tried to leave the country. However, they were caught. King Louis XVI was in January 1793. A few months later, Queen Marie Antoinette met the same fate.

The execution of the king and queen was followed by the Reign of Terror. During this period, anyone believed to be against the revolution was sent to the guillotine . This lasted for about ten months. Between 14,000 and 40,000 people were .

The unrest went on for many years. France's first ended in 1799. That's when Napoleon Bonaparte became emperor. Napoleon led the country into many wars. He also brought slavery back to France.

Following the Revolution of 1789, France went through two more revolutions. They were in 1830 and 1848. Many experts also believe the French Revolution helped shape revolts in Haiti and Russia. Today, France is a democratic republic.

Experts today disagree about the legacy of the French Revolution. Many see it as a step in France's journey to become a . However, the Reign of Terror and rule of Napoleon cause others to criticize the war. What do you think?

C3.D3.His.2, CCRA.R.4, CCRA.L.3, CCRA.L.6, CCRA.R.1, CCRA.R.2, CCRA.R.10, CCRA.SL.1, CCRA.W.2, CCRA.W.9, CCRA.L.1, CCRA.L.2

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Many of our Wonder Friends know about Bastille Day. Others may have read about Napoleon Bonaparte. Maybe you've heard that Marie Antoinette said, "Let them eat cake!" These are all important parts of today's Wonder of the Day-the French Revolution. The French Revolution is also known as the Revolution of 1789.

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Many people in the United States are fascinated by royalty. That's probably because, unlike many other countries, we don't have kings and queens here in America.

Ready to take a peek under the to get the on royalty? All of us have different ideas about royalty.

Young children, for example, probably think about princesses, like Cinderella, when they hear the word royalty. Others might immediately think of the British royal family, like Prince William, or American women who became real-life princesses, like Princess Grace of Monaco.

Kings, queens, princes, and princesses - they seem like larger-than-life figures who live privileged , almost- lives. Yet, they're also human beings like the rest of us. No one can deny, though, that they lead lives quite different than most.

Royalty developed centuries ago under the feudal systems of medieval Europe. Under , a few landowners gained large territories through either military force or purchase.

The mightiest of these landowners was crowned king. Other, less- landowners gained titles by pledging their allegiance to the king and managing smaller territories on his behalf.

Over time, a king would die, and his would succeed him, usually according to the rules of inheritance of money and property. Other nobles would pass on their titles and positions to their in a similar way.

In this way, many European countries developed a complex system of royalty over many hundreds of years, including a wide variety of special traditions and rituals. Although Europe was the only place with a true feudal system, monarchies (governments ruled by royal families) also developed in a similar fashion in Japan and the Middle East.

In the 17th to 19th centuries, many monarchies were replaced with democratic governments that featured leaders by the people. When this happened, the royal family often kept an important, but mainly , role in the government, while actual power was held by officials.

Were you born into a royal family? Probably not. Let's face it, the odds are against you. But that's OK. A very select few people still marry into royal families from time to time.

Before you start searching for a prince by kissing frogs, though, you might want to ask yourself an important question. Would you really want to be royalty?

Sure, the crowns and fancy clothes are nice. But royals are also subjected to intense . Would you want your every move watched by others?

Depending on what country you live in, you might have a royal that's something other than king, queen, prince, or princess. Here are a few royal titles used now or in the past in other countries:

Russia: czar/czarina

Asia and Africa: emir

Japan and Ancient Rome: emperor/empress

Ancient Egypt: pharaoh

India: raja

Iran: shah

Muslim countries: sultan

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Many people in the United States are fascinated by royalty. That's probably because, unlike many other countries, we don't have kings and queens here in America. Ready to take a peek under the to get the on royalty? All of us have different ideas about royalty.

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Join us in Wonderopolis today as we go up, up, up to learn about what brings us down, down, down!

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Defining Gravity: Crash Course Kids #4.1

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun.

What else does gravity do?

Why do you land on the ground when you jump up instead of floating off into space? Why do things fall down when you throw them or drop them? The answer is gravity: an invisible force that pulls objects toward each other. Earth's gravity is what keeps you on the ground and what makes things fall.

Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.

Earth's gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That's what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here.

You exert the same gravitational force on Earth that it does on you. But because Earth is so much more massive than you, your force doesn't really have an effect on our planet.

Gravity in our universe

Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made.

Gravity not only pulls on mass but also on light. Albert Einstein discovered this principle. If you shine a flashlight upwards, the light will grow imperceptibly redder as gravity pulls it. You can't see the change with your eyes, but scientists can measure it.

Black holes pack so much mass into such a small volume that their gravity is strong enough to keep anything, even light, from escaping.

Gravity on Earth

Gravity is very important to us. We could not live on Earth without it. The sun's gravity keeps Earth in orbit around it, keeping us at a comfortable distance to enjoy the sun's light and warmth. It holds down our atmosphere and the air we need to breathe. Gravity is what holds our world together.

However, gravity isn't the same everywhere on Earth. Gravity is slightly stronger over places with more mass underground than over places with less mass. NASA uses two spacecraft to measure these variations in Earth's gravity. These spacecraft are part of the Gravity Recovery and Climate Experiment (GRACE) mission.

GRACE detects tiny changes in gravity over time. These changes have revealed important details about our planet. For example, GRACE monitors changes in sea level and can detect changes in Earth's crust brought on by earthquakes.

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Gravity is the force by which a planet or other body draws objects toward its center.

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Today's Wonder of the Day was inspired by LAUREN from Winston-Salem, NC. LAUREN Wonders, " How does technology help us with almost everything? " Thanks for WONDERing with us, LAUREN!

What challenges do you face every day? Some kids have a hard time tying their shoes or being on time for the school bus. You might find it challenging to read the front board. Many kids have a hard time hearing their teacher from across the room. Others struggle with gym class activities.

All people have personal challenges . But you probably also have some special ! You might be a great writer or artist. Maybe you can do more cartwheels than anyone else in your class. Your talent could be listening or being a good friend.

How do you use your ? Many people enjoy using their to help others. Take your teacher for example. They use their special every day to help you learn and grow. Many other people use their special skills to help others with the challenges they face.

How about people who work in technology ? Many of them use their to make new devices that help others. Do you use any gadgets at school? Access to a device and the Internet can open up a world of learning. For many children with learning disabilities, new educational technology can help them learn.

And there are plenty more examples. Many smartphone applications help people face challenges . For example, money reading apps help people with impairments identify the value of the money they're holding. If your eyesight is limited, you know just how helpful that can be. It helps people use the right bills and make sure they get the correct change back.

Text-to-speech technology is also a huge help to many people. Kids use it to follow along with texts that are hard to read. Adults also use text-to-speech . They listen to emails and other important documents if they can't see them. Speech-to-text technology also allows people with limited hearing to read the words they can't hear.

Have you ever lost the use of a leg? Whether briefly or permanently, you know how useful wheelchairs can be. And they're becoming more advanced every day! Prototypes already exist for wheelchairs that can climb stairs. And scientists are even working on wheelchairs that can be controlled with just the mind. They'll read brain waves to find out exactly what their user wants them to do.

Voice technology already lets people control devices with the sound of their voice. You can find it in many products. There are voice keyboards, cars, smartphones, and many others. And of course, driverless cars can may improve transportation for people with and impairments . Many models of these cars are in testing and could be on the road soon!

What does the future hold for technology ? You might be amazed at some you'll see in your lifetime. Maybe you'll even come up with the next helpful device yourself! If technology isn't your passion, there are plenty of other ways for you to help others. All are useful-especially when they're used to help people face challenges !

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Today's technological Wonder of the Day could be life changing!

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Do you get to play with any cool gadgets at school? Today, many schools make technology part of learning. That means you may get the chance to use personal computers, laptops, or tablets. You may even use smartphones in the classroom.

Classrooms have not always had the supplies they use today, though. One-room schoolhouses once used hornbooks. Those were wooden paddles. They had lessons written on them to teach. We've come a long way since then!

There was even a time before students had pencils and paper. Instead, they used slates. These were small, handheld blackboards that they could write on with . Can you imagine taking notes on those?

In fact, the classroom chalkboard didn't come along until the late 1800s. With this new tool, the entire class could see what teachers were writing at the same time. Chalkboards seem like a thing of the past today. But they were cutting-edge technology at one time!

Over the years, new items were added to classrooms. found ways for new devices to improve learning. They started using film projectors , radios, and televisions. Soon after came videotape players and overhead projectors .

Copying machines also brought big changes when they came along in the mid-1900s. Teachers could give students copies of lessons for homework and studying. This lets the classroom reach beyond its walls.

The use of audio tapes and headphones in the classroom made learning new languages easier. They also helped students with vision or reading impairments . With these new tools, they could listen to lessons instead of reading them.

Handheld calculators made math class easier for students. They also helped math teachers move more quickly through topics.

There are hundreds of other examples of educational technology over the years. Many changes have come in the past couple of decades, though. Schools have seen a lot of growth in the use of cutting-edge technology .

Then came the invention of the personal computer. Education took a huge leap forward. Soon after came the Internet. Modern education looks very different than it did when your parents were in school.

Today, it's not uncommon for children to use their own laptop or tablet computers in school. Other schools may use handheld computers or smartphones. Some schools even use the Internet to connect with other teachers and schools around the world!

You may even be reading today's Wonder of the Day via the Internet in your classroom! How cool is that? Some classes even use technology to make their own websites. They share with their friends and relatives what's going on in their classroom.

Does technology help you learn? Or would you rather work with pencils and paper? Maybe you'd love to try out a ! The next time you're at school, take a good look around. What examples of technology can you find?

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If you use Wonderopolis at school, then today's Wonder of the Day is especially for you!

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DK Learning Downloadable Content Hub - Penguin Random House

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Downloadable resources formerly available on dklearning.com

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Generating, consuming, distributing and making electricity

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Generating, consuming, distributing and making electricity

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Click on all 4 links on the map to read all of the information.

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DK Find Out! | Fun Facts for Kids on Animals, Earth, History and more!

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Visit DK Find Out! to learn about dinosaurs, space, animals, nature & more. Fun learning activities for kids with videos, quizzes & galleries at DKFindOut.com

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Deepest Part of The Oceans -  Full Documentary HD

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From generating electricity to growing crops, dams have proven to be one of the most useful innovations in human history. Find out how these simple structures accomplish so much.

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Grand Ethiopian Renaissance Dam Project, Benishangul-Gumuz

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The Grand Ethiopian Renaissance Dam (GERD) is located in the Benishangul-Gumuz region of Ethiopia, on the Blue Nile River.