DK Children’s Encyclopedia)_clone

Precious metals SEE ALSO ▸▸ Aircraft p.13 Precious metals are rare and worth a lot of money. They are ▸▸ Elements p.90 found in the ground as pure metal or combined with other ▸▸ Metals p.162 elements in rocks. Silver and gold are the best known and ▸▸ Money p.169 have been treasured for thousands of years. Other precious ▸▸ Gold pp.200–201 metals include platinum and beryllium. ▸▸ Rocks and minerals p.214 Gold The highest quality Silver flutes are made of Pure gold is a very soft metal. solid silver. This precious metal, To make it harder—so that we along with gold and can make useful objects out of mercury, has been it—we combine gold with small used by humans since amounts of other metals. prehistoric times. A mobile phone Gold This ancient Silver is used contains just a tiny earrings Egyptian burial in many of today’s amount of gold—about mask is covered batteries. 0.001 oz (0.025 g). in gold foil. Cutlery DVD The most valuable coins have always been made of gold. Pieces of jewelry Mirror are often made from platinum. Platinum bar Catalytic converters Platinum is used in Watch Beryllium in cars contain pacemakers. These platinum. It makes devices can keep a Beryllium is a steel-gray precious metal. exhaust fumes person’s heart beating. It is a vital component of computers, less poisonous. cars, aircraft, phones, 199 medical equipment, Platinum and many other hi-tech gadgets. Just a few hundred tons of platinum are produced each year. Fighter aircraft Because it is so rare, it is used in very small amounts.

The story of... Meteor shower This gold mask is thought to Gold When Earth first formed, show the gold and other metals sank deep Greek hero Gold is a precious metal that has been into the core. Other gold, found Agamemnon. used to make jewelry and decorations near the surface of our planet, since ancient times. It is rare and very arrived later from space. Asteroids expensive. But that’s just the start rained down in a powerful storm, of its story. Gold has a glittering history and is still popular bringing gold with them. all over the world. Gold nugget Digging for gold In the past, a single nugget could change the life of a gold-digger. When gold was found in the US in the 1800s, it started a “gold rush.” Thousands of people, known as prospectors, traveled to the US hoping to find gold and become rich. Large gold mines 25 have created huge holes deep percent of all the into the ground. world’s gold is stored in a New York City vault. Gold mine Centuries of sparkle Pieces of gold found loose on the Earth’s surface can be picked Gold was the first metal to be discovered and used up by hand. Bigger quantities by humans. It is beautiful and deep underground must be dug shiny, as well as soft and bendy. This makes it ideal for shaping out in a process called mining. Modern mines use heavy into jewelry, including delicate rings, bracelets, machines to dig chunks of rock and necklaces. that contain traces of gold. 200

The world’s Golden money oldest coins The first gold coins were made by King Croesus in 564 bce. All coins were made from used to be made of precious metals, electrum—a including gold and silver. However, modern coins are usually made of mixture of gold and silver. cheaper metals, such as copper, nickel, and zinc. Sacred manuscripts Gold leaf were decorated with gold leaf. For centuries, gold has been used to decorate religious buildings, works of art, and objects. As well as using the solid metal, gold can be thinned down into very fine sheets called gold leaf. Gold leaf is used to decorate books and paintings. A model of the spacecraft used in the 1969 moon landing. The mask was Golden craft The visors of discovered by space helmets archaeologists Space scientists use sheets of in a burial tomb gold foil to cover parts of some are coated in a thin in 1876. spacecraft and satellites they layer of gold to send into space. The foil keep astronauts protects them by reflecting cool and safe. the sun’s harmful rays during their journey. 201

Prehistoric life SEE ALSO ▸▸ Dinosaurs p.80 Earth has changed a lot over many millions of years. It has ▸▸ Early humans not always been home to plants, animals, and people. Many early living things no longer exist, so we only know p.82 about them from their remains. The distant past is known ▸▸ Earth p.83 as “prehistory.” ▸▸ Fossils p.111 ▸▸ Habitats p.126 Ammonites were ▸▸ Oceans and seas animals with shells that lived in water. p.187 Forests As Earth warmed up, plants grew on land and forests provided food for different types of animals. Oceans The first life was in the oceans. There were underwater plants and early animals. Dinosaurs were the main land animal in prehistoric forests. Ice ages In times when the Earth cooled down, most of it was covered in ice. Animals had to adapt to survive. Woolly mammoths had thick fur coats to help them keep warm in the ice ages. Stone Age After the last ice age, Earth warmed up to how it is today. A great variety of plants and animals live in many different habitats, such as deserts, forests, and polar regions. Early humans invented ways to hunt and gather food, and survive longer. 202

Radio SEE ALSO ▸▸ Atmosphere p.33 Radios pick up signals and turn them into sounds we can ▸▸ Books p.44 hear. They do this by using invisible waves that carry ▸▸ Communication sound information. Thousands of different radio stations play music, news, and drama to listeners all over the world. p.69 ▸▸ Hearing p.127 ▸▸ Navigation p.182 ▸▸ Television p.251 How radio works 2. Radio waves 3. Radio antenna Invisible radio waves carry An antenna is a thin Radio towers turn sounds into sounds from radio towers to metal rod that picks radio waves. Radios pick up radios in the home. up radio waves. these waves and turn them back into sounds that you can hear. 1. Radio tower Radio towers have antennas on the top of them. These antennas send out radio waves. Radio waves travel at the speed of light—about 186,000 miles (300,000 km) a second! 4. Speaker Remote Controller The radio’s control Remote control toy car speaker plays the waves as sounds. Wireless gadgets use radio waves to contact Radio towers each other. For example, are tall to make a remote control can sure that radio tell a toy car how to waves can travel move around. over buildings. 203 Digital radio Instead of radio waves, digital radio uses digital signals that don’t get broken up like radio waves do. This means they sound better.

Rain forests SEE ALSO ▸▸ Birds p.39 Rain forests are forests with tall trees and lots of rain. ▸▸ Forests p.109 Tropical rain forests are hot places. They are home to ▸▸ Habitats p.126 nearly half of all animals and plants in the world. The ▸▸ Materials p.157 trees are so thick with leaves that very little sunlight ▸▸ Plants p.194 reaches the forest floor. ▸▸ Trees p.261 ▸▸ Weather p.271 Amazon rain forest This harpy eagle hunts for animals Emergent layer The world’s largest rain forest is in the treetops. Only the tallest trees reach the Amazon in South America. This this top layer of the rain forest. rain forest surrounds the Amazon River. Its trees and plants provide Howler monkeys food and shelter for many animals. get together and howl each morning. This large blue Morpho The leaves of Toco toucans use butterfly is brown on the bromeliads catch their long beaks to other side of its wings, so water that small reach fruit to eat. it can hide when resting. animals come to drink. Canopy layer This is a thick layer of leaves and branches. Most rain forest animals live here. Emerald tree boas squeeze animals to death before eating them whole. Jaguars hunt other A praying mantis Some trees have animals and climb waits for other giant buttress roots trees to rest and eat. insects to come that help them soak close, then grabs up water quickly. Understory and eats them. Shrubs and new trees The bright red leaves grow in this hot, dark This many-legged surrounding the flowers layer of the rain forest. centipede can kill of the heliconia stricta bigger frogs, spiders, look like lobster claws. Forest floor and snakes. This dark, damp layer is This long-tongued covered in dead leaves that giant anteater can eat have fallen from above. 30,000 ants a day. Capybaras are good swimmers and eat water plants. 204

Recycling SEE ALSO ▸▸ Changing world Recycling means reusing garbage or making it into new things rather than burning it or burying it in the ground. pp.50–51 Everything from paper, glass, metal, and plastic to phones and computers can be recycled. The more we recycle our ▸▸ Climate change waste, the less we damage our planet. p.60 ▸▸ Computers p.71 ▸▸ Metals p.162 ▸▸ Plastic p.195 ▸▸ Pollution p.198 Paper and Food waste cardboard Leftover food can Old paper and cardboard be fed to animals, such can be mashed up in as pigs or chickens, or water, then rolled used to make compost flat and dried to to help plants grow. make new paper products. Plastic Metal Most of the plastic Cans can be melted we throw away can be down. They are either chopped up, melted remade into more cans down, and re-formed or used to make other into new items. metal goods. Glass Electronics Bottles and jars Devices such as made of glass can be phones and laptops cleaned and used again can be repaired or have or melted down to make their valuable metal new glass objects. parts taken out to be reused. 205

The story of... Festivals Festivals are celebrated across the world. Some festivals, like Eid or Christmas, mark important religious events. Others, like the Chinese New Year, mark the passing of time. Festivals are often a time of joy. People might put up lights, dance, or give each other presents. Christmas Christmas trees are often finished Every year at Christmas, with a star or angel Christians celebrate the birth of on top. Jesus Christ. Some go to church and sing carols or special songs about Presents are the event. Most people give presents placed below to each other and have a large a decorated meal with special food. Many Christmas tree. people spend Christmas with friends and family. The “Elegant Skull” is a symbol of the Day of the Dead. Day of the Dead In Mexico, people celebrate the Day of the Dead for three days at the start of November. This ancient festival is held to remember friends and family who have died. People build shrines to the dead and bring gifts of food and drink to their graves. Elegant Skull A Chinese Dragon statue puppet that is used in festival celebrations. 206

Chinese New Year Muslims say the Eid special Eid prayer Celebrations for the outside a mosque. Muslims celebrate the Eid Chinese New Year last for al-Fitr holiday at the end of 15 days. Families clean their Ramadan. During Ramadan, they houses to sweep away bad luck, fast, or go without food during decorate their windows and the day. At Eid, Muslims give doors with red paper shapes, and enjoy a big feast together. Some money to charity, pray people throw firecrackers to together, visit friends make a big noise, and dragons and family, and enjoy dance in the streets. a feast. At New Year, Passover Passover is one of Chinese parents Jewish people celebrate the most important give their children Passover to remember the Jewish festivals, and escape of the Jews from slavery money in red in Egypt. The festival lasts for seven is more than packets. or eight days and is marked with the special seder, or meal, which includes 3,000 matzo—a flat, or unleavened, years old. bread that hasn’t been given time to rise. Dancers control the colorful dragons using long sticks. The special food Fireworks light up on the plate the sky at Diwali, tells the story the festival of the Jews’ escape of lights. from slavery. Diwali The Hindu festival of Diwali takes place every fall in the north of the world and every spring in the south. It celebrates the victory of light over darkness and good over evil. People light up their homes and public places and set off fireworks. 207

Religion SEE ALSO ▸▸ Ancient India A religion is a set of beliefs. Religions often try to explain the world, such as how it came to exist. Religion is an p.19 important part of many people’s lives. They agree with their religion’s teachings, and try to behave by its rules, for ▸▸ Dance p.76 example, about how to treat other people. Many religions have central figures that are prayed to, called gods. ▸▸ Festivals pp.206–207 ▸▸ Turkish Empire p.262 ▸▸ World p.275 Buddhism Special candlestick Judaism Buddhists follow the called a Menorah Judaism dates back teaching of Buddha, who 4,000 years. Jews lived in India in the fifth believe in one God who created the world. century bce. They meditate, which involves They trace their history back to the thinking deeply. They Hebrew people of believe that they will be what is now Israel. reborn after death. Buddha statue Sikhism Gurdwara World religions Islam Sikhs follow the The followers of Islam teachings of Guru Granth More than 75 percent of Mosque are called Muslims. They Sahib. They believe that believers follow Buddhism, believe that the Quran, all people are equally Islam, Christianity, or Hinduism. their holy book, is God’s important. Sikhs pray in Judaism and Sikhism also have word told through his grand buildings worldwide followings. There messenger Muhammad, called Gurdwaras. are many other religions, but fewer people follow them. whose teachings they follow. The H indu god Shiva Hinduism Jesus on Christianity Hinduism began in India the cross Christians have one God. more than 2,500 years They believe that their 208 God’s son Jesus lived on ago. Hindus pray to Earth 2,000 years ago. many gods and believe He died nailed to a cross so that Christians could that life is a circle of birth, death, and rebirth. have life after death.

Renaissance SEE ALSO ▸▸ Aircraft p.13 Italy experienced great change in science and art between 1400 and 1600. This movement then spread ▸▸ Ancient Rome across Europe. It was called the “Renaissance,” which p.20 means “rebirth,” because it looked at ideas that originally came from ancient Rome and Greece. ▸▸ Art p.28 ▸▸ Inventions pp.136–137 ▸▸ Religion p.208 ▸▸ Writing p.280 Buildings The great dome Science of the cathedral Renaissance builders in Florence was Scientists began to copied ancient styles built in 1436. carry out experiments for to produce larger, more the first time. They made elegant buildings. These important discoveries about This flying buildings often had space, science, and medicine. machine was columns and domes. designed by Leonardo da Vinci. It never actually flew. Art This painting, by Pietro The people at the front of Perugino, shows Jesus the painting appear larger Renaissance artists used a more realistic style giving the keys of than those farther away. than previous artists. They tried to show light Heaven to St. Peter. This is called perspective. and shade and came up with new types of paint and materials. 209

Reptiles SEE ALSO ▸▸ Amphibians p.15 Reptiles are scaly-skinned, cold-blooded animals. Most ▸▸ Antarctica p.24 reptiles lay soft, leathery eggs. A baby reptile grows inside ▸▸ Deserts p.78 the egg and then, when it’s ready, breaks its way out. ▸▸ Dinosaurs p.80 There are four main groups of reptile. ▸▸ Eggs p.86 ▸▸ Evolution p.95 ▸▸ Sun p.247 All reptiles have Some lizards scaly skin. can move their eyes to look in two directions at once. Lizards These reptiles have many skills. This chameleon can change the color of its skin. Other reptiles can run up walls, or break off their tails to escape danger. Tortoises have hard shells. Tortoises Reptiles live on Crocodiles Crocodiles and and turtles and alligators alligators have every continent strong jaws. Turtles live in water These giant reptiles have and tortoises live on except Antarctica. existed since before dinosaurs. Basking the land. Their shells They hide under water, then protect them, but are spring up to catch their prey Reptiles are cold-blooded heavy, so they move and drag it under. animals. They get the heat very slowly out their bodies need from the of the water. world around them, lying in the sunshine to warm up. They hide in the shade to keep themselves from overheating. Snakes All snakes swallow their prey whole. They smell using their tongues. Some snakes have poisonous bites, but most are not dangerous to people. 210

Rivers SEE ALSO ▸▸ Farming p.98 Starting as tiny streams, rivers flow from mountaintops down to the ocean. They provide a home to lots of wildlife. ▸▸ Water People transport things along rivers, grow crops next pp.120–121 to them, and even use rivers for spare-time activities, such as sailing and fishing. ▸▸ Glaciers p.122 ▸▸ Lakes p.143 ▸▸ Water cycle p.270 ▸▸ Weather p.271 River system Small streams Rain and snow fall flow downhill and to make streams. Water flows down the mountains, come together making small streams. These streams to make rivers. join up to form rivers, which wind along and then eventually flow into the ocean. Some rivers start from lakes. Dams use water Farms use movement to river water create electricity. to grow crops. On flatter ground, rivers follow wide, steady bends called meanders. Rivers become River habitats are wider and deeper home to many downstream. kinds of wildlife. Rivers provide Fishing nearby towns and cities with water. The “mouth” of Water a river is where sports Mighty river it joins the ocean. The further rivers get from the mountains, the deeper Rivers are used to and more slow-moving they transport people become. Eventually they spill and goods to the out into a lake or the ocean. ocean and beyond. 211

Robots SEE ALSO ▸▸ Computers p.71 Robots are computer-controlled machines that do jobs ▸▸ Factories p.97 for us. They can be used in many ways, such as helping ▸▸ Machines p.150 doctors, building things, and doing jobs that would be ▸▸ Medicine p.160 too dangerous for people to do. ▸▸ Space travel p.237 Types of robot Eye sensors Humanoid robot allow the Some robots are designed Robots are carefully designed to robot to “see.” to look a bit like people. This do their jobs. Each type of robot robot is called NAO. It can has its own unique look. dance and speak. Each “finger” has a Robots can see different function. and feel, but not like humans. Their sensors use code to interpret feedback. Medical robot Hand sensors Robots are capable of performing very allow NAO to delicate movements. They can help “feel” objects. doctors operate on their patients. Factory robot Robots in space Robots are strong, and are good at doing the NASA uses robots to perform same thing over and dangerous tasks in outer space. over again. This makes This robot mends things on the them useful in factories. International Space Station. Motors allow the Foot sensors are used for robot to move up walking, climbing stairs, and down. and detecting obstacles. 212

Rock cycle SEE ALSO ▸▸ Earth’s surface Rock may be very hard, but it does not last forever. It is constantly being worn away by wind, water, p.84 and ice. At the same time, new rock is being made at the bottom of the sea and by volcanoes. This is ▸▸ Erosion p.93 called the rock cycle. ▸▸ Inside Earth p.135 ▸▸ Mountains p.172 ▸▸ Rocks and minerals p.214 ▸▸ Volcanoes p.268 Recycled rocks Cooling Heated and Magma erupts squashed Tiny pieces of volcanic rock are from volcanoes. washed into the sea and settle on It cools and hardens Any rock can be changed the sea bed. They become buried by to form a type of into metamorphic rock by new layers of rock particles that get rock called volcanic, the heat and the weight squashed together to form new rock. or igneous, rock. of the rock above it. Slate, As this new rock is buried deeper, which is used to make roof it gets hotter and melts to form tiles, is a common magma. Magma rises and cools metamorphic rock. to form new volcanic rock. Breaking down Volcanic rock is broken up by wind, rain, and ice. Tiny particles of the broken rock are washed into the ocean by rain. Settling Pieces of volcanic rock settle on the sea bed. They are buried and squashed to make a type of rock called sedimentary rock. Changing Melting Lots of layers If sedimentary rock Deep in the Earth, where is buried deep enough, it is extremely hot, rock Most rocks being formed it is changed by heat melts to form magma. In today are sedimentary and the weight of the some places, magma rises rocks. They are made from rock above it into to the Earth’s surface, tiny pieces of older rocks metamorphic rock. forming volcanoes. that build up on the sea bed in layers. Sandstone is a common sedimentary rock. 213

Rocks and minerals SEE ALSO ▸▸ Earth’s surface The Earth’s surface is made up of hard natural objects called rocks. Rocks are made up of a mixture p.84 of substances called minerals. There are many different kinds of rocks and minerals. ▸▸ Elements p.90 ▸▸ Gemstones p.118 ▸▸ Metals p.162 ▸▸ Rock cycle p.213 ▸▸ Volcanoes p.268 Rocks Metamorphic rock Under great heat and pressure, Types of rock have different metamorphic rock is formed names depending on how they deep inside the Earth. were formed. The three types are called sedimentary, igneous, and metamorphic. Sedimentary rock When particles of minerals settle and are squashed together, they slowly become sedimentary rock. Minerals There are Igneous rock This type of rock is formed A mineral is a naturally occurring solid. It is made nearly 4,000 when melted rock cools from chemical elements—simple substances down and becomes solid. that cannot be broken down further. Minerals different types grow together to form rocks. Glowing rocks of minerals Some rocks look plain in daylight, but on Earth. their minerals change color under special “ultraviolet” light. The glowing minerals in this rock are called calcite and willemite. Serpentine Amethyst Garnet Opal 214

Satellites SEE ALSO ▸▸ Astronomy p.32 Satellites are objects that go around, or orbit, something bigger. There are more than 2,000 artificial satellites ▸▸ Clouds p.64 orbiting the Earth. They are used for a variety of different jobs. Some track the weather while others let us ▸▸ Communication communicate with each other. p.69 GPS satellite ▸▸ Internet p.138 The global positioning system (GPS) ▸▸ Solar system gives us our exact position on the p.23s Earth. The system uses more than 20 satellites, working together ▸▸ Universe p.263 to pinpoint your location. Local satellites This satellite always stays over this area. Some types of satellite stay over the same area as they orbit the Earth. These are called geostationary satellites. To cover the whole Earth, many satellites are needed. Photos of When this the Earth flap is open, are sent to the telescope weather takes photos. stations. Solar panels collect the sun’s rays to power the satellite. Communication satellite Weather satellite Hubble space telescope These satellites pick up signals and These satellites take pictures of the This satellite points away from the send them to other places in the world. clouds and measure land and sea Earth and takes detailed images of the They are used for phone calls and live temperatures. This information helps universe. It lets us see farther into video communications. us to study and forecast the weather. space than we could from the Earth. 215

Saturn SEE ALSO ▸▸ Astronomy p.32 Saturn is the second largest planet in the solar system after Jupiter and the sixth farthest planet from the sun. ▸▸ Atmosphere p.33 It is a “gas giant,” mainly made of hydrogen and helium, and is best known for its rings. ▸▸ Jupiter p.141 ▸▸ Moon p.171 ▸▸ Exploration pp.180–181 ▸▸ Solar system p.233 Ringed planet Icy rings Saturn's rings are made Saturn is surrounded by huge rings of chunks of ice, rocks, that stretch over a vast distance. and dust. However, they are only a few hundred feet thick. Saturn Gaps between rings The gaps between the rings are areas with less ice and dust. Moons of Saturn The unmanned spacecraft Cassini Like Jupiter, Saturn has more than 60 moons. Titan, the largest moon, has lakes of liquid methane and a thick atmosphere. Enceladus, Saturn's sixth largest moon, shoots out water from its south pole. Titan Huygens probe Cassini-Huygens The Cassini spacecraft explored Saturn between 2004 and 2017. A probe called Huygens, carried by Cassini, landed on the surface of Saturn's moon Titan in 2005. 216

Science SEE ALSO ▸▸ Astronomy p.32 Science is the search for truth and knowledge. It’s about ▸▸ Biology p.38 understanding the world and learning how and why things ▸▸ Chemistry p.58 work the way they do. Science includes doing experiments ▸▸ Medicine p.160 to test predictions and collect evidence. We divide science ▸▸ Physics p.192 into three main areas: chemistry, biology, and physics. ▸▸ The sciences pp.218–219 Biology The study of living things and their surroundings is called biology. It includes the human body, plants, and animals. Physics Chemistry Physics studies Looking at what light, sound, forces, things are made of is waves, magnets, known as chemistry. This electricity, energy, includes the tiny building and the planets. blocks of all materials, Scientists called atoms. Scientists are people who investigate the world Science isn’t to answer questions and find solutions to just facts in a book— problems. They do experiments to see if ideas are right or wrong, and they share information. it’s a whole way Inventions Copy of Thomas Edison of thinking and Edison’s invented the discovering. Studying science helps us to light bulb electric light bulb create new things. For example, in 1879, while if we understand movement, we studying electricity. can design better cars. If we understand the body, we can invent medicines to help fight off sickness. 217

The story of... The sciences For thousands of years, people have been observing the world around them and coming up with ideas to explain why things behave the way they do. Science is about answering questions with ideas, evidence, and experience. Child making Some of the earliest Notches around a wave in a doctors were ancient the edge were bottle lined up with 5,000Egyptian women, objects in the sky. years ago. Curing diseases 1. Bacteria growing In 1928, Scottish scientist Alexander Fleming noticed how a mold called penicillin killed bacteria. This discovery led to a type of medicine called antibiotics. They have been killing germs in the human body ever since. Experiments 3. Bacteria dies In ancient Greece, a man called Aristotle said that people 2. Penicillin should look at nature and carry introduced out experiments to find answers to their questions. Scientist do Renaissance experiments to test their ideas Starting in the 15th and to make new discoveries. century, the Renaissance was an explosion of ideas that Compasses helped transformed science and art in explorers to travel Europe. Leading experiments, the world and gathering evidence, and sharing discover new ideas. ideas became popular—this led to new inventions and discoveries. Early compass 218

Accidental inventions Many great scientific discoveries have been made by accident. For example, German scientist Wilhelm Conrad Röntgen accidentally discovered X-rays in 1885. He was sending electricity through tubes of gas when he noticed that he could see what was inside a nearby box. He then used this finding to take pictures of the bones inside his wife. Nebra Sky Disk The night sky Early X-ray X-rays pass Renaissance One of the earliest sciences through skin and artist and scientist was studying the movements flesh but bounce of the moon, planets, and stars. back off bones. Leonardo da This is now called astronomy. Moon Vinci sketched calendars were first made about Scientific drawings pictures of humans 10,000 years ago. Around 4,000 and animals he years ago, the Nebra Sky Disk Many scientists create beautiful, was used to track seasons and precise drawings to record their findings. had cut up. Mary Anning was a famous British fossil the sun’s position. hunter who lived in the 1800s. Mary found her first fossils as a child and made drawings of them. Her discoveries helped scientists to understand how life existed in the oceans millions of years ago. The Plesiosaurus’s Plesiosaurus drawn by Mary Anning in 1824 paddles have bones that are also present in legs and feet. 219

Seashore SEE ALSO ▸▸ Birds p.39 The area where land meets the sea or ocean is called the ▸▸ Habitats p.126 seashore. It may be sand, mud, or rock. Animals and plants ▸▸ Invertebrates p.139 that live here have to be able to survive crashing waves ▸▸ North America and the water level changing twice a day. p.184 Shore zones California gulls ▸▸ Oceans and seas soar over the The seashore has different zones, which are shores, searching p.187 divided by the distance they are from the ocean. for fish, insects, ▸▸ Tides p.254 Animals in the low tide zone are mostly in the and eggs to eat. water all the time, while those in the high tide Brandt’s cormorants zone have to survive in air when the tide is out. rest together on rocks near the water. California sea Brown pelicans Spray zone lions rest on land have a pouch in This area is not underwater, in large numbers. their beak to but is splashed by wave store food. after wave. Acorn barnacles close up during low tide. High tide zone Sea otters have Kelp are tall This area is only thick fur to keep sea plants. covered in water when them warm. the tide comes in. Hermit crabs live in California blue seashells to keep mussels clean themselves safe the sea water. from other animals. Sculpin fish eat small fish and shellfish. Purple sea urchins Green sea move around using anemones are suckers on their animals with long, tube-shaped feet. armlike tentacles. Low tide zone Purple ochre sea US Pacific coast This area is stars can survive for This seashore is home to covered in water eight hours without thousands of different animals most of the time. being in water. and sea plants. The coastline has cool temperatures. 220

Seasons SEE ALSO ▸▸ Climate change In many parts of the world, the year has four seasons. These seasons are winter, spring, summer, and autumn. p.60 The lives of plants and animals, the weather, and the hours of daylight all change from one season to the next. In some ▸▸ Day and night p.77 hot parts of the world, there are just two seasons. ▸▸ Hibernation p.129 ▸▸ Solar system p.233 ▸▸ Trees p.261 ▸▸ Weather p.271 Changing seasons In the cold winter, plants stop growing. In spring, they begin to grow again and baby animals are born. Summer sees the hottest weather, and then in autumn leaves change color and fall off the trees. Winter Spring Summer Autumn What causes December the seasons? March The Earth travels around the sun. It is tilted so some This part of the Earth parts of it get stronger tilts away from the sunlight than other parts. sun and has its winter. As it moves, the amount of sunlight reaching Sun different parts of the Earth changes. This This part of the Earth September Monsoons gives us our seasons. tilts toward the sun and has its summer. Tropical parts of the Earth are warm Axis all year round. There are often just June two seasons—a dry season and a rainy season, called a monsoon. 221

Shapes SEE ALSO ▸▸ Constellations Shapes are areas with different outlines. In math, there are two types of shape. Two-dimensional shapes have p.73 length and width, while three-dimensional shapes have ▸▸ Flags p.102 length, width, and height. Shapes can be made of straight ▸▸ Maps p.155 or curved lines, or a mixture such as in a semicircle. ▸▸ Numbers p.185 ▸▸ Symmetry p.248 ▸▸ Volume p.269 What makes a shape? Edge Line The side of a shape A straight line is the A shape is named depending on the number is called an edge. shortest distance of sides and angles it has. Regular shapes between two points. have sides that are all the same length. Angle Point An angle is the A point is a place place where two on a shape. It is lines meet. shown with a dot. Triangles have three sides and Circles have one long, round side. Squares have four equal sides and three inside angles adding up to 180°. four right angles. Angles Right angle Polygons An angle of Angles are measured in degrees (º) out exactly 90º. “Polygon” is the name of 360. Angles have different names 90° for any flat, two- depending on how big they are. dimensional shape. 240° Acute angle Reflex angle Pentagons have five equal sides An angle less An angle between and five inside angles. than a right 180º and 360º. angle (90º). 45° 222 Obtuse angle An angle between 90º and 180º. 135°

Sharks SEE ALSO ▸▸ Conservation Sharks are a type of fish. Almost all of them eat meat. They are found in every ocean and some rivers. There are more p.72 than 400 types of sharks. Most are active during the day, but some hunt at night. ▸▸ Fish p.101 ▸▸ Food chains p.107 ▸▸ Oceans and seas p.187 ▸▸ Prehistoric life p.202 Sharks have good Great white shark eyesight even when there isn’t much light. This shark eats other animals. It mainly hunts and feeds on fish, but Sharks have also eats turtles, been around for dolphins, and seals. more than The front fins can be used to slow 400 million down the shark. years! The pointed The tail moves from nose is used to side to side to power sniff for food. the shark forward. The sharp, pointed teeth are perfect for ripping food. Each whale Whale shark The back fins stop shark has its the shark from own pattern This is the largest fish rolling over. of spots. in the world. It can travel Sharks under threat Hammerhead shark thousands of miles every year. The number of sharks is getting smaller Hammerhead sharks use their because they are hunted for their fins, wide heads to pin down teeth, and fish oil. Scientists try to learn stingrays on the about sharks, so that they can help them. ocean floor. The eyes are a long way apart, letting the shark see far to spot its prey. 223

Ships SEE ALSO ▸▸ Oceans and seas Sea transportation comes in all shapes and sizes, from tiny sailing boats to large cruise liners and p.187 gigantic container ships. They can be used for sports, ▸▸ Sports p.239 to take people on vacation, and to move things from ▸▸ Trade p.257 one country to another. ▸▸ Transportation The captain Cranes load pp.258–259 steers the containers on ▸▸ Work p.274 ship from and off the ship. the bridge. Container ship Containers are Some of the largest boats large metal boxes. on the oceans are container Each container can ships. These giants of the hold around 6,000 seas can transport more shoe boxes. than 15,000 containers full of items such as clothes, toys, and televisions to different countries. Sailing boat The hold carries more Submersible containers. Some store This tiny boat doesn’t have an hundreds of cars. This craft doesn’t travel on the engine. It is powered by wind, ocean, but underneath it. It can which is caught in the sail take scientists deep underwater to push the boat to look at sea life and study across the water. the ocean floor. Cruise ship A cruise ship is a floating hotel that takes tourists to different countries. On board are swimming pools, theaters, and water slides. 224

Sickness SEE ALSO ▸▸ Body cells p.41 Tiny living things called germs can make us sick if they get ▸▸ Human body inside our bodies. Germs are all around us—in the air, in our p.130 food, and on the things we touch. Our bodies have many different ways to stop them from harming us. ▸▸ Medicine p.160 ▸▸ Microscopic life p.165 ▸▸ Skin p.229 Body defenses ▸▸ Taste p.249 The body has a defense system to Tears stop germs from getting in. It also Watery tears wash dirt kills germs that find a way in. out of our eyes. They also kill germs. Mucus (nose and throat) Ear wax Mucus traps germs we Ear wax flows out of our breathe in. Hairs move the ears, pushing germs and mucus to the mouth, where dirt out with it. the germs and mucus get swallowed. Saliva Also known as spit, saliva Senses protects your mouth by Sight, smell, and taste killing germs. help us avoid eating food that has gone bad. Skin White blood cells Avoiding Skin stops germs Tiny white blood sickness from entering the cells in your blood kill body by forming a germs in the body. Covering our nose and protective barrier. mouth when we sneeze or cough stops germs from 1,000 Acid spreading through the air. germs can fit on Chemicals in the head of a pin. the stomach They’re tiny! kill most germs we swallow. Good bacteria Helpful bacteria in our intestines stops germs from growing. 225

Sight SEE ALSO ▸▸ Body cells p.41 Sight is seeing the shapes, sizes, and colors of ▸▸ Brain p.45 nearby and faraway objects within our surroundings. ▸▸ Cells p.56 When we see, colored light is bouncing off objects ▸▸ Hearing p.127 and into our eyes. ▸▸ Light p.147 ▸▸ Muscles p.173 How we see Glasses ▸▸ Smell p.232 Tiny sensors at the back of the eye receive If an eye lens doesn’t focus Some people use glasses light and send signals to the brain to make the light in the right place, to help them read an image from the light we see. the image is blurred. Glasses contain lenses that Retina Eyelid change where the light In the retina at the focuses in the eye, so the back of the eye, tiny Eyelashes image becomes clear. sensors called “cells” collect information Tear duct about color, light, Liquid is made and shape. here. When we blink, our eyelids wipe our eyeballs with the liquid, to clean out dust. Iris Pupil The iris is the colored part of Outer eye the eye. It changes the size of the Iris round hole in the middle—the pupil. Cornea The cornea bends the light entering the eye. Just one-sixth Pupil Eyeball The pupil gets bigger of the eyeball can to let in more light Optic nerve when it’s dark and gets The optic nerve sends be seen from smaller to let in less the light information outside. light when it’s bright. collected in the eye to the brain. Lens The lens focuses the light at the back of the eye. It makes the picture we see clear. Muscles 226

Sinking and floating SEE ALSO ▸▸ Forces p.108 When we place objects in water they can float on the ▸▸ Gases p.117 surface or sink below it. The heavier and more packed ▸▸ Gravity p.125 together a material is, the more likely it is to sink. Materials ▸▸ Materials p.157 like stone and metal usually sink, while wood and plastics ▸▸ Metals p.162 usually float. ▸▸ Ships p.224 Floating The weight Salt water has of the duck If the downward force of an pushes down. more buoyancy object’s weight is less than the force of the water The duck is full of than fresh water, so pushing up on it, it will float. air, making it light The more air an object and buoyant. we can float more contains, the more likely it is to float. easily in the ocean than in a lake. Buoyancy Buoyancy The weight As the duck pushes some pushes the of the coin of the water out of the duck upward. is pushing way, the water pushes it down. back on the duck. The effect of the upward The coin sinks push of the water is a because its weight force called buoyancy. is greater than its buoyancy. Massive ships Sinking It seems amazing that huge metal ships float while small metal coins sink. Ships float because they are An object sinks when full of air and because they have a large surface area. the force of its weight The force of buoyancy pushing upward is spread out pushing downward is and is greater than the ship’s overall weight. greater than the force of buoyancy pushing The buoyancy of the back up on it. coin pushes it up. 227

Skeleton SEE ALSO ▸▸ Brain p.45 All the bones in the human body fit together in the ▸▸ Heart p.128 skeleton. They make up the shape of the human body. ▸▸ Human body The skeleton forms a protective cage around the soft, inner organs like the lungs and the heart. p.130 ▸▸ Lungs p.149 ▸▸ Muscles p.173 Our bones Skull The hinge The skull protects the joint lets the The skeleton is made up delicate brain inside. arm move up of 206 bones. The bones are moved Ribcage Ball and and down. by muscles. socket joint Ball and socket Hinge joint Saddle joint joints in the A saddle joint shoulder and hip Joints allows the allow a swivel thumb to move movement. Joints are the places where one bone in a circle. joins another to allow movement. They Humerus Ulna let our bones move side to side, up and down, or in circles. Joints have fluid in Pelvis Radius them to help make movement smooth. Spine The spine is made up of 24 bones called vertebrae. Femur Inside bones The ends of The outer layer of bones Spongy bone bones are harder is made from a strong at the joints. substance called calcium. Inside is the bone marrow, Bone is which supplies blood cells to the rest of the body. stronger Tibia Types of bone Bone marrow than wood, Compact bone concrete, There are two kinds of or steel. bone inside each bone. Blood Hard, compact bone gives the bone strength and protection. Spongy bone is full of little holes that make the bone lighter. 228

Skin SEE ALSO ▸▸ Body cells p.41 Skin is the stretchy outer layer of the body. It keeps our ▸▸ Cells p.56 inside parts inside and germs outside. It protects us from ▸▸ Genes p.119 water and sunshine, and keeps us at the right temperature. ▸▸ Heart p.128 The outer layer continually flakes off as new skin is made. ▸▸ Human body Inside the skin Pore p.130 Sweat comes ▸▸ Touch p.256 The skin is split into layers. out of the skin Below the outer layer that from holes Hair you can see, there is a lot called pores. Thin hairs going on. grow out of tiny pits called hair follicles. Epidermis The epidermis is the stretchy outer layer of skin we can see. Sweat gland Dermis Produces sweat to cool This is the area the skin. More sweat is where sweat made if the body is warm. and oil are made to keep the skin Skin color stretchy. A chemical in our skin Fat called melanin controls Fat helps skin color. The more cushion knocks melanin you have in and bumps. It your skin, the darker it also stores is. It is made in the energy for epidermis, the top layer the body. of skin. Nerves Blood vessels Skin is the body’s Nerves send signals These tubes carry to the brain that tell blood around the biggest organ. us the texture, body. They get temperature, and wider to allow more It weighs pressure of the blood to flow and to things we touch. help the body to 8.8 lbs (4 kg)! cool down. 229

Slavery SEE ALSO ▸▸ Africa p.12 Slaves are people who have had their rights taken away and are treated like property. They may have been captured in ▸▸ Ancient Rome war, owe more money than they can pay, or have parents p.20 who are slaves. Slavery has been used throughout history, but today it is against the law in every country in the world. ▸▸ Law p.145 ▸▸ North America p.184 ▸▸ Ships p.224 ▸▸ Trade p.257 Slave labor In the early 1800s, big farms called plantations in the US used slave labor to pick cotton, cut sugar cane, and perform other tasks. Slaves worked long hours in very bad conditions. Slavery today Though slavery is now illegal, more than 20 million people are still kept as slaves, mostly in Asia and Africa. Groups around the world are working to solve this terrible problem. The slave trade People were often chained and packed To keep American plantations supplied with tightly into slave ships. workers, ships carried slaves from Africa to America. Between 1450 and 1850, 12 million 230 people crossed the Atlantic Ocean.

Sleep SEE ALSO ▸▸ Brain p.45 Every night we sleep and our bodies rest, repair, and grow. While we sleep our brains sort through the information ▸▸ Eating gathered from our senses and some of it is deleted and pp.104–105 some is stored as memories. We need sleep to stay fit and healthy. ▸▸ Hibernation p.129 Sleep patterns ▸▸ Human body Our sleep follows a pattern of p.130 different stages. You go through each stage several times every night. ▸▸ Sickness p.225 8 p.m. 9 p.m. 10 p.m. 11 p.m. 12 a.m. 1 a.m. 2 a.m. 3 a.m. 4 a.m. 5 a.m. 6 a.m. 7 a.m. Awake Dreaming Light sleep Shallow sleep Deep sleep When we wake up, We dream when we’re Breathing slows We move around This is when our we become alert close to waking. We down but the brain is more during shallow bodies are growing and aware of our have three to seven still active and you sleep than during and repairing muscle, surroundings. dreams a night. can wake up easily. deep sleep. tissue, and bones. Why do we Memory Energy You will sleep? Our brain deletes useless If we don’t get enough information and stores sleep, we lack energy spend one-third Sleep is important more important things and want sugary food. because without it our while we sleep. of your life asleep. brain and body slowly Growth This is around stop working. Healing Our bodies grow and repair Our bodies heal better and muscles and bones while 30 years faster when we get plenty we are in a deep sleep. of solid sleep. in total! 231

Smell SEE ALSO ▸▸ Brain p.45 Smell is one of our senses. When tiny parts of something ▸▸ Hearing p.127 float through the air and into our nose we identify a smell. ▸▸ Human body The brain tells us what it smells like compared to other things we’ve smelled before. p.130 ▸▸ Muscles p.173 This area works out what ▸▸ Skeleton p.228 the smell is and sends ▸▸ Taste p.249 information to the brain. The brain How we smell These cells are tells us about sensors that the smell. Anything that smells releases tiny detect smells. particles into the air. The particles mix Mucus with a sticky fluid in our nose called This sticky fluid mixes mucus. Sensors in the nose detect with the smell to help the smell and send signals to the brain the sensor cells to identify it. detect what it is. Nose bone We can detect The smell enters the nose. Nose cavity more than This is the main airway for breathing. It is connected 10,000 to the throat and mouth. different smells with our nose! The tongue has sensors for tasting food. Taste and smell Smell and taste are closely linked. If you hold your nose, you will find it harder to figure out what something tastes like. 232

Solar system SEE ALSO ▸▸ Asteroids p.30 The solar system is made up of our star, the sun, and ▸▸ Comets p.68 everything that travels around it. This includes eight ▸▸ Earth p.83 planets and their moons, asteroids, and comets. Scientists ▸▸ Jupiter p.141 think the solar system formed 4.6 billion years ago, ▸▸ Neptune p.183 from a massive spinning cloud of gas and dust. ▸▸ Sun p.247 ▸▸ Universe p.263 8 6 3 4 5 Sun 1 72 Asteroid belt Orbiting planets 1. Mercury 2. Venus 3. Earth 4. Mars Mercury is the The surface of Venus Earth has lots of Mars has a red, The sun is the center of the smallest planet. is super-hot. liquid water. dusty surface. solar system. Everything in the solar system travels 5. Jupiter 6. Saturn 7. Uranus 8. Neptune around, or orbits, the sun. Jupiter is the Saturn is famous for Uranus is thought to Neptune has strong largest planet. the rings around it. be the coldest planet. winds and giant storms. Types of planet Kepler-16b There are three types of planet in the solar system. There are many other solar systems The rocky planets orbit close to the sun, and the gas in the universe. Scientists have even and ice giants orbit farther away. found a planet, called Kepler-16b, iter that orbits two suns. e Earth Neptun Jup Rocky planets Ice giants Gas giants Mercury, Venus, Earth, and Uranus and Neptune are Jupiter and Saturn Mars are small and rocky with made of a mixture of gas are huge planets solid surfaces. and icy materials. made of gas. 233

Solids SEE ALSO ▸▸ Changing states Solids are materials that keep their shape. They don’t flow like water—they stay where you put them. Solids p.57 are useful for making many things, from mobile phones ▸▸ Gases p.117 to houses. They are usually hard materials, but soft ▸▸ Liquids p.148 materials that keep their shape are solid, too. ▸▸ Materials p.157 ▸▸ Metals p.162 What solids do Particles ▸▸ Plastic p.195 Solids are made from tiny Solids can be hard, bendy, particles that are close Cutting solids strong, squishy, see-through, or together. If enough heat magnetic. The behaviors of a is added, they start to We can cut solids into solid are called its properties. move past each other different shapes. Wood is to become liquid. a solid material that comes from trees. We cut and shape it to make furniture. Solids make a pile, not a pool or puddle. Chopped wood Solid rocks become Shaping solids liquid lava when Metal is a hard solid we can find underground. We heat heated to very metal to make it soft, then bend and hammer it into the high temperatures. shape we want. When it cools, metal keeps its shape. Solids keep their shape. A hot metal horseshoe Making new solids We can make new solid materials Liquid gelatin Gets chilled by mixing other materials together. Solid gelatin For example, gelatin is made by adding hot water to gelatin powder to make a liquid. The liquid then cools into a solid. 234

Sound SEE ALSO ▸▸ Gases p.117 A sound is made when something vibrates. The bigger the vibration, the louder the sound is. The faster something ▸▸ Hearing p.127 vibrates, the higher pitched the sound is. Sound vibrations travel through things to get to our ears. ▸▸ Liquids p.148 Sound vibrates ▸▸ Musical through the air. instruments p.175 ▸▸ Music pp.176–177 ▸▸ Solids p.234 The voice box Our ears detect vibrates when the vibration we speak, and our brain making sound. understands them as sound. How sounds travel Big, slow Sounds travel by vibrating the air until it reaches vibrations our ears and we hear the sound. The vibrations are called sound waves. Sound waves can travel Big drum through solids, liquids, and gases. The big drum vibrates more slowly, so it has a lower note Volume Small, fast compared to the small drum. vibrations It’s bigger, so it makes bigger Volume changes depending vibrations that are louder. on how big a vibration is. The bigger the vibration, the louder the sound. How high or low a sound is depends on how fast something vibrates. The faster the vibration, the higher the sound. Things sound Small drum We can hit a small louder when drum harder to they are close make it louder, but it vibrates at the to us. same speed so it has a constant note. 235

South America SEE ALSO ▸▸ Amphibians p.15 The continent of South America is surrounded by ocean, except at the top where it joins with North America. ▸▸ Explorers p.96 One-third of the continent is covered by a huge jungle, called the Amazon rain forest. The Andes mountain range ▸▸ Incas p.132 stretches all the way down one side of South America. ▸▸ North America p.184 ▸▸ Rain forests p.204 ▸▸ World p.275 The giant tortoises Virgen de Pitcher of the Galápagos la Paz plant Islands can live for more than 150 years. Giant tortoise Anaconda Amazon Canoes theater Capybara About Bogotá South Cathedral America Piranha Flute Kapok Qualea tree grandiflora Population: Andean Llama 422.5 million condor Reed boat Amazon rain forest Leatherback Soccer turtle The world’s biggest Highest point: Aconcagua forest, the Amazon, is Salt lakes Pampas Christ the This soapstone home to thousands of grass Redeemer statue is 128 ft species of plants and (39 m) high. It Lowest point: animals. Many native, overlooks the Laguna del Carbón Brazilian city of Rio de Janeiro. or indigenous, tribes live in the forest, too. Polo Machu Picchu Biggest desert: Built by Inca emperor Atacama Desert Pachacuti in 15th-century Peru, Machu Picchu is a Longest river: Andean Inca builders used Amazon goose interlocking stones spectacular mountain-top that fitted together town. Many thousands of The skin of the Perito Moreno very tightly. people visit it every year. golden poison dart Glacier frog is covered in a deadly poison. Magellanic penguin 236

Space travel SEE ALSO ▸▸ Astronauts p.31 Space travel is how we explore the solar system and learn about our place in the universe. Most space ▸▸ Moon p.171 travel is done using robot spacecraft called probes. The farthest in space that humans have traveled ▸▸ Exploration themselves is to the moon. pp.180–181 Humans in space ▸▸ Radio p.203 ▸▸ Robots p.212 ▸▸ Solar system p.233 The outside fuel To get into space, people use super- It takes a tank is filled with powered spaceships. Space shuttles like liquid hydrogen and Atlantis were used to take people into robot spacecraft oxygen to power space for 30 years. Now people use about six months to the shuttle’s the Russian Soyuz spacecraft. engines. travel to Mars. Solar cells use the sun’s power to make the probe work. Astronauts Juno probe sit in the cockpit. Robots in space Magnetometer measures magnetic fields. Probes gather data using cameras, magnetometers, and radars, then send the data back to Earth. This booster Extreme environment rocket gives extra power. Space is not an easy place for people to be in. It can be both extremely hot and cold. There Launch of the are dangerous rays from the sun and there is space shuttle no air to breathe. Spaceships and stations are Atlantis carefully designed to keep astronauts safe. Astronaut Karen Nyberg washes her hair on board the International Space Station. 237

Spiders SEE ALSO ▸▸ Animal groups Spiders are animals with two body segments and eight legs. They are predators, hunting other small animals to p.22 eat. They do not chew their food, but turn it into liquid before sucking it up. ▸▸ Animal homes p.23 Tarantula ▸▸ Food chains p.107 Some of the world’s ▸▸ Insects p.134 largest spiders are tarantulas. As they get ▸▸ Invertebrates bigger, their old skin p.139 comes off and they grow a new one. ▸▸ Sight p.226 Tarantulas Leg hairs help bite with their tarantulas feel the venomous fangs, vibrations of other but their bite is less animals nearby. harmful to humans than a bee’s sting. Spider webs The row of eyes Spiders can Many spiders build webs, help the jumping using silk that they make in spider see all grow back their their bodies. Some spiders around it. use their web to trap and legs if they store the insects they eat. break off. Jumping spider The body is designed Jumping spiders can jump 30 times for speed. their body size. They use their good eyesight to spot other animals. Huntsman spider These spiders don’t build webs, but hunt and forage for insects. Females can go for three weeks without eating. 238

Sports SEE ALSO ▸▸ Ancient Greece Sports are physical activities performed by individuals or teams of players. There are usually rules to sports, and p.18 team sports often take place in a set amount of time. ▸▸ Bicycles p.36 Individuals and teams compete against one another to ▸▸ Dance p.76 achieve the best result or the highest score. ▸▸ Games Athletics Spectators pp.240–241 Spectators watch sports ▸▸ School Athletics is a group of sports that take and cheer on their place around a running track or on a favorite athletes. pp.272–273 sports field. Big athletic competitions such as the Olympics have lots Archery of events. Archers use a bow to fire arrows at a circular target. Sprinting Javelin A sprint is a race A javelin is a long that is shorter spear thrown as far than 400 m. as possible. Shotput High jump Long jump Athletes compete High jumpers Long jumpers try to to throw a small, compete to jump launch themselves heavy ball the the highest over as far as possible farthest distance. a bar. along a sandpit. Judges Hurdles Athletes jump over a series of obstacles called hurdles on a running track. Team sports Gymnastics Winter sports Sports such as football, rugby, Strong gymnasts use their bendy In cold weather, competitors and cricket are played between two bodies for moves including flips and use snow and ice to ice-skate, opposing teams. The team that scores handstands. They use the floor as well ski, snowboard, and bobsled. the most goals or gets the highest as props such as balancing beams. Many winter sports involve number of runs or points wins the game. performing tricky moves, or racing. Soccer teams Basketball teams Football players pass a round ball pass a round ball pass an unusually- Skier by foot. by hand. shaped ball by hand. Gymnasts can do impressive moves while standing on their hands. 239

The story of... Racket sports Games Tennis, badminton, and squash are sports played using a A game is an activity or sport played racket on a special court. In tennis, using a set of rules. Games are played opponents hit the ball across a by individuals or by teams of players, who compete against each other. Some central net, and in badminton games use balls and bats or rackets they hit a shuttlecock. In and are played on special courts; squash, the players hit the others use boards with specially ball against a wall. designed game pieces. The tennis racket frame has strings pulled tightly across it. Board games A chessboard has Ping a grid of black and pong ball Tabletop games, such as white squares. chess and backgammon, are played on specially built boards. The start of a Each player has a number of game of chess pieces, such as chessmen, that they move according to a set of rules. Board games were first played in ancient Egypt 5,500 years ago. Stone ring to hit the ball through. Ball and wall games Australian Handball rules football The ancient Mayans of Central America played a ball game on long, narrow, stone-walled courts. Players used a solid rubber ball, which they had to keep in play by using only their hips and arms—they weren’t allowed to touch it with their hands or feet. Stone-walled Baseball Mayan ball court 240

The first The Olympics Olympic Every four years, athletes Games were compete for their country in held in ancient the Olympic Games. The Greece in Olympics includes lots of 776 bce. different sporting events, Lacrosse including athletics, ball gymnastics, and team sports. Olympic sprint relay race Football Golf ball The first computer game was developed in 1947. Players fired a dot at a target. Volleyball Computer games Ball sports Soccer ball Computer games are played on a computer or through a console Ball sports are among the most popular games of all. on a TV screen. Many games Teams of up to 15 players per side include special effects and music. play in matches of soccer, rugby, basketball, football, Australian rules They can be one-player or football, cricket, and other games. multi-player games. Huge crowds watch these matches, many of which are shown on television. Basketball Rugby ball A child plays a computer game. 241

Stars SEE ALSO ▸▸ Color pp.26–27 Stars are balls of very hot gas, deep in space. From Earth, they look like tiny dots but are actually huge. The smallest ▸▸ Galaxies p.116 ordinary star is about the same size as Jupiter. Stars shine because the gases inside them constantly crash together ▸▸ Light p.147 in a process called fusion. ▸▸ Solar system p.233 ▸▸ Sun p.247 ▸▸ Temperature p.252 Sizes and colors Stars come in different sizes and colors. A star’s color depends on how hot its surface is. The hottest stars are blue, and the coolest ones are red. Blue supergiant These stars are very young and extremely hot. Red giant star Red giants are older stars with cool surface temperatures. Sun Our sun is a middle-aged, medium-sized star with a medium surface temperature. The nearest star Star deaths The star closest to the Earth Some stars end their after our sun is Proxima lives in a spectacular Centauri, a red dwarf with at explosion called a least one planet. This star is supernova. Others 9,000 times farther away slowly fade as they than Neptune, the planet run out of energy. farthest from the sun. 242 Cloud of material from a supernova explosion

Stone Age SEE ALSO ▸▸ Art p.28 The Stone Age was a period of time that began about ▸▸ Buildings p.48 3.3 million years ago and lasted until about 4,000 years ▸▸ Caves p.55 ago. In the Stone Age, people made tools out of stone for ▸▸ Early humans the first time. They used them to cut meat and plants, to build shelters, and, in the late Stone Age, for farming. p.82 ▸▸ Farming p.98 ▸▸ Food p.106 Stone tools Finding food Blueberries Stone Age people began Finding food was the most Bison making stone tools to do important part of life for Hunting for big different tasks. Using tools people in the Stone Age. animals, such as meant people could get They ate wild plants, and bison, could be food or do work more animals from land and sea. dangerous. quickly and easily. Salmon A stone axe helped to chop wood and Buildings dig into dirt. The first Stone Age People made handaxes buildings were made to help them cut meat of wood and animal and chop hard plants. skins. By the end of the Stone Age, people Cave painting had begun building large stone structures Some Stone Age people called megaliths. made beautiful artwork on cave walls, often showing the Stonehenge in England animals they would hunt. These is a famous Stone Age paintings are still being found today. megalith that is still standing today. Paint could be made from powdered fats and minerals. Lascaux cave paintings in France 243

The story of... Grand palaces Homes The kings and queens of Europe were very rich and A home is a house or building in lived in magnificent palaces which you live. That home might be and castles. They feasted in built of canvas, stone, bricks, wood, or ice. It could even be carved out of great halls and received solid rock. Homes can be built visitors in grand separately as single, detached throne rooms. houses or built together as row houses or terraces. Some homes are built on top of each together in blocks called apartments. Early homes Some early Neuschwanstein Castle in Germany people built simple Some early people made their homes in caves or grass shelters. holes dug into sides The layering of of mountains and hills. grasses is called Others cut down trees to build simple wooden huts, thatching. which they draped with Eco homes Solar panels on animal skins. the roof make Today, some homes are energy from specially built to work with sunshine. Caves were the natural world, or easy to turn environment. They don't use into homes, as they didn't have up as much energy as to be built! ordinary homes. Caves in Cappadocia, Turkey Rainwater is Walls have collected for added layers reuse. to save heat (this is called insulation). 244

Igloo Extreme homes In the cold Arctic, some Inuit people build shelters called igloos out of blocks of ice. Igloos keep out the wind and are warm inside. Plan for Future homes House 3D-printed designed by houses on the What will homes of the Antoni planet Mars future look like? Some might be Gaudí built using a method called “3D Houseboat in India printing.” With this method, robots add material layer upon layer to create a three-dimensional shape. Moving homes Some people live in homes that can move from place to place. They float in houseboats on water or live in wheeled caravans towed by cars or horses. Architecture Architecture is the art of designing and making buildings. In Barcelona in Spain, architect Antoni Gaudí was inspired by nature and decorated his buildings with different materials and colorful patterns. 245

Storms SEE ALSO ▸▸ Climate change Storms are powerful winds that often bring rain, thunder and lightning, snow, hail, dust, or sand. Storms can cause p.60 serious damage if they have very high wind speeds or heavy rain that leads to flooding. Tornadoes, hurricanes, ▸▸ Clouds p.64 and thunderstorms are all types of storm. ▸▸ Electricity p.87 ▸▸ Erosion p.93 ▸▸ Water cycle p.270 ▸▸ Weather p.271 Tropical giants The hurricane's eye, The strongest or center, is calm, with winds surround The biggest and most destructive storms, very little wind. the storm's eye. called hurricanes or typhoons, happen in tropical areas, above warm water. They begin when groups of smaller storms spin together into a spiral shape. Thunderstorms Storms with thunder and lightning are common in summer. They often have heavy rain or hail that can break things and cause floods. Hurricanes Tornadoes are given people’s names, such as Tornadoes are fast- spinning columns of air Alex, Matthew, that form during massive and Patricia. thunderstorms. A tornado can destroy everything in its path. 246

Sun SEE ALSO ▸▸ Atmosphere p.33 ▸▸ Atoms p.34 The sun is the star at the center of our solar system. It is ▸▸ Gases p.117 one of at least 100 billion stars in our Milky Way galaxy. ▸▸ Magnets p.151 The sun gives off light and heat, making it possible for life ▸▸ Milky Way p.167 to exist on Earth. ▸▸ Solar system p.233 Massive explosions ▸▸ Stars p.242 send jets of gas out from the surface. Yellow dwarf Astronomers describe the sun as a yellow dwarf, although it is a medium-sized star. It is a hot ball of gases Dark sunspots are that are constantly the cooler regions on the move, on the sun’s creating energy. surface. These bright bursts of energy are called solar flares. 1.3The sun is Loops of gas are called million prominences. times bigger than Earth. Auroras Final stages of the sun Toward the top and bottom of the Earth In about 5 billion years (at its poles), particles time, the sun will have from the sun meet used up most of the gases Earth’s magnetic field. that keep it shining. It will This colorful glow is collapse into a small, very called an aurora. hot white dwarf. It will then slowly cool down and 247 eventually fade away.

Symmetry SEE ALSO ▸▸ Art p.28 There are two types of symmetry. Reflective symmetry is when lines can be drawn to divide a shape into identical ▸▸ Flowers p.103 parts. Rotational symmetry is when a shape can be turned around (rotated) and still look the same. ▸▸ Human body p.130 ▸▸ Shapes p.222 ▸▸ Sight p.226 ▸▸ Games pp.240–241 Reflective symmetry A regular octagon has eight lines of Lines of symmetry are like folding a shape in half. If a symmetry, through shape is symmetrical, both sides of the fold will look the its sides and angles. same. Shapes can have more than one line of symmetry. This triangle has Diamonds have two three lines of lines of symmetry. symmetry, one Each one splits the through each side. diamond into two equal parts. Diamond Equilateral triangle Octagon Symmetry in nature Rotational symmetry A circle has Nature has many examples of both types of If a shape can be turned and a never-ending symmetry. Most animals, including humans, are its outline looks the same, it roughly the same on both sides—they have a line has rotational symmetry. This number of lines of symmetry down the middle. sequence shows how a square of rotational has rotational symmetry. symmetry. Reflective Rotational Direction symmetry symmetry of rotation 12 3 4 Point of rotation Leaf Starfish A square can turn within 248 its shape four times.