DK Children’s Encyclopedia)_clone

Lungs SEE ALSO ▸▸ Brain p.45 We breathe air in and out of our lungs. The lungs take ▸▸ Gases p.117 oxygen from the air and transfer it to the blood. Every part ▸▸ Heart p.128 of the body needs oxygen, so the lungs collect it and the ▸▸ Human body blood carries it around the body. p.130 ▸▸ Skeleton p.228 ▸▸ Sound p.235 Lungs Nose Oxygen is taken Air enters and leaves into the blood and The lungs are two spongy bags our bodies through carbon dioxide is filled with tubes and air sacs. The our nose and mouth. sent out of the air sacs are where gases change blood in the air sacs. places. Oxygen is breathed in and Trachea carbon dioxide is breathed out. This tube carries air into our lungs. It is Bronchi also known as the These two air tubes windpipe. connect the trachea to the lungs. Bronchioles Alveoli, or air sacs The air goes into these tiny tubes. Air enters the Air leaves the Voice box Each one ends in air lungs as we lungs as we sacs called alveoli. breathe in. breathe out. The voice box is in the throat. It stops food from getting into Diaphragm The rib muscles The rib muscles the lungs and makes us cough This muscle changes pull up to make relax so the if any food gets in. The voice the shape of the the ribcage ribcage gets box also lets us speak and sing. lungs so we can bigger. smaller. breathe in and out. The diaphragm The diaphragm Breathing pulls down to relaxes and pull air into the the lungs get Muscles work lungs. The lungs smaller, pushing together to let get bigger. air out. us breathe in and out. We have a 149 diaphragm muscle below the lungs and more muscles around the ribcage. They change the size and shape of the lungs.

Machines SEE ALSO ▸▸ Aircraft p.13 Machines help us do things. They usually perform tasks ▸▸ Bicycles p.36 that are too big, small, boring, long, or dangerous for ▸▸ Electricity p.87 people to do. Most modern machines are powered by ▸▸ Energy pp.88–89 electricity or gas. ▸▸ Engines p.92 ▸▸ Robots p.213 Simple machines Pulley Wedge ▸▸ Trains p.260 A pulley uses a rope or chain Made of wood or metal, this Simple machines reduce the looped over a wheel to lift triangular tool can be used to Screws effort needed to do things. heavy loads. push things apart. These sharp metal pins are used A person must operate the to attach things. As the screw is machine, but only a small turned, it moves down and around. amount of effort is required to move heavy objects. The operator Big machines sits in the driver’s cabin. Backhoes are made up of several simple machines. They are powered by engines. Lever Levers move like arms. This one raises a metal scoop to collect building materials. Wheel Wheels make it easier to move heavy things around. Why we use Neat work Repetitive work Dangerous work machines A sewing machine can sew Automatic cash machines Robots are used to study active more neatly and more quickly don’t sleep, so they can give volcanoes, so people do not have to Machines are usually than most people can by hand. out money 24 hours a day. put themselves at risk. more efficient and reliable than human 150 workers. This is because they can do things without ever becoming bored, tired, slow, or distracted.

Magnets SEE ALSO ▸▸ Compass p.70 Magnets are objects that other magnets and some metals ▸▸ Earth p.83 stick to. They have two sides, or ends, called poles. The ▸▸ Electricity p.87 area all around the magnet where the magnet acts is called ▸▸ Inside Earth the magnetic field. p.135 ▸▸ Forces p.108 ▸▸ Materials p.157 Magnetic materials Magnetic force Materials that magnets Two identical poles repel each other, stick to are called magnetic pushing each other away. Two opposite materials. Any metal that poles attract each other and stick. contains iron is magnetic, but most metals are Two south poles push not magnetic. each other apart. NS SN SN SN A north and a south pole attract each other. This paperclip is being attracted to the magnet. Magnetic field The magnet acts on things that are nearby. The region where the magnet attracts or repels magnetic materials is called the magnetic field. Magnetic field lines travel from north to south. N The largest The paperclips S magnet on Earth contain iron, so they stick The magnetic is Earth itself. to the magnet. field is strongest at the poles. The whole planet 151 is a magnet with two poles.

The story of... Pets Pets have become an important part of humans’ lives. Many animals are kept as companions, for work, or to help people go about their daily lives. It is estimated that 44 percent of homes in the world have a pet. Canaan dog Pets big and small First pets Pets aren’t just dogs and Dogs were the first animals cats—we keep all sorts of to be kept as pets. They were animals as pets. They vary from used for hunting—helping early big dogs and horses to small humans to catch food. Ancient snakes and hamsters. Each species needs a special diet art from 12,000 years ago shows humans and and room to exercise. dogs together. Dog Bronze statue Bearded dragon of a cat from ancient Egypt Holy cats Goldfish The ancient Egyptians Hamster loved cats. They caught mice, Gerbil rats, and snakes, which kept people’s homes clean. Cats were also believed to have special powers for guarding children. The punishment for killing a cat was death. Snake 152

Helpful pets Guide dogs are specially Dogs are good at keeping trained to help people company. They are also people who need easy to train, and can be used to help seeing. help people with disabilities. A dog can be a person’s eyes or ears, and help them get around. Budgie Pets in space For years, animals have helped scientists answer questions about how humans would survive in space. Dogs Belka and Strelka (above) were sent into space on the Sputnik 5 in 1960. They returned safely to Earth using a parachute. Cat Rabbit Guinea pig Not pets Tarantula It is illegal to keep some animals. Wild animals, such as monkeys, can even be dangerous. Before getting a pet, make sure you know that the animal has come from a good home and has not been taken from the wild. 153

Mammals SEE ALSO ▸▸ Animal families Mammals are animals that have body hair and feed p.21 their babies on milk made by the females. They are ▸▸ Animal groups warm-blooded, which means their bodies stay the p.22 ▸▸ Food chains p.107 same temperature. There are many ▸▸ Habitats p.126 ▸▸ Vertebrates different groups of mammals. A mother elephant is pregnant p.266 Mammal babies for nearly two Gemsbok’s Mammals give birth to live babies. years before its horns grow Parents feed and care for their young longer each until they can look after themselves. baby is ready year. to be born. Cheetahs have Each hoof sharp hearing to has a hard help them catch covering. animals to eat. Gemsbok Plant-eaters Animals that eat plants are called herbivores. They have special teeth for cutting and chewing leaves. Fur or hair on the body keeps mammals warm. Cheetah Asian elephants Meat-eaters Pouched mammals Dolphins Meat-eating animals Some animals, called marsupials, Not all mammals live are called carnivores. look after their babies in a on land. Dolphins are They hunt other special pouch. The baby mammals that live in animals for food. stays in the pouch, water. They come up to drinking milk until it is the surface to breathe The pouch is big enough to leave. through a blowhole at a warm place the top of their head. for the baby. Red kangaroo 154

Maps SEE ALSO ▸▸ Compass p.70 A map is a detailed picture of what the ground looks like from above, as if you were flying over it. Maps tell us how ▸▸ Explorers p.96 big an area is and what can be found there. Maps can be of anything, from the whole world to the insides of buildings. ▸▸ Measuring p.159 1 ▸▸ Exploration 2 pp.180–181 3 4 ▸▸ Navigation p.182 ▸▸ Transportation pp.258–259 Using a map N Key This shows which direction We can use a map to A Road the top of the River map is pointing work out the height WE Footpath toward. This of the land, to follow is usually north, Railroad or “N.” roads and railroads, S or to find our way to a hospital or school. B The map is C Railroad station A key shows divided into Bridge which real-life a grid with features the squares for Castle map’s lines different areas. Campsite and symbols represent. D The scale bar E Hospital Symbols shows the Nature reserve are used real-life distance for different between points School features, such on the map. Sports center as buildings and campsites. 0 km / O miles 1 km / 0.62 miles Ancient maps Forest Maps were less accurate in The end of the past. This 2,500-year-old paper maps? stone map shows how people in Babylon (modern-day Iraq) Paper maps are still around saw the world. today, but fewer people use them. Most cars now have GPS Babylon is shown to guide the driver, and digital at the center of maps can be viewed on mobile the world. phones or laptops. Phone map 155

Mars SEE ALSO ▸▸ Ancient Rome Named after the Roman god of war, this rocky planet has huge volcanoes, ice caps, and deep canyons. It was p.20 once a wet, warm world where water flowed. Now, ▸▸ Asteroids p.30 Mars is a cold, dry world covered in craters. ▸▸ Elements p.90 ▸▸ Rocks and minerals Mars’ surface features a giant p.214 volcano called ▸▸ Space travel p.237 Olympus Mons. ▸▸ Volcanoes p.268 Thousands of craters formed when asteroids hit Mars 3.5 billion years ago. Red planet Mars is called the red planet because its surface is covered in a layer of reddish dust. When the wind blows, this dust enters the atmosphere and turns the sky red. Cameras photograph and video details on the surface. Mission to Mars Mars is about half the size Since 1976, spacecraft of Earth. have visited Mars to study its surface. Moons of Mars Two twin rovers called Spirit and Opportunity Mars has two tiny moons called arrived on Mars in Deimos and Phobos. These rocks 2004, and Opportunity may have started as asteroids. is still exploring. Phobos is the largest, measuring 16 miles (27 km) in length. 156 Spirit rover Deimos Phobos Instruments take rock samples.

Materials SEE ALSO ▸▸ Atoms p.34 Materials are what all things in the world are made of. ▸▸ Buildings p.48 We describe them using their properties, which are how ▸▸ Electricity p.87 they behave and what they do. They can be hard, bendy, ▸▸ Gases p.117 waterproof, or magnetic. Materials will either float or ▸▸ Liquids p.148 sink, and electricity can pass through some of them. ▸▸ Plastic p.195 ▸▸ Solids p.234 Solubility Conducting heat The rubber handle stays Solubility is how easily something Metals are good at conducting heat, cool, so we dissolves (mixes into) liquid. If you put which means when something hot can pick up salt in water, the salt dissolves into it, touches them, the heat transfers into the pan. so salt is soluble. Soluble materials them. Wood, plastic, and rubber are can be solids, liquids, or gases. poor conductors of heat. Both properties are useful in saucepans. Sand is insoluble— This purple it does not dissolve powder dissolves in water. into the water. The flame causes the metal pan to heat up. Conducting electricity Flammability Copper conducts electricity, which means Flammability is how easily something catches fire it allows electricity to flow through it. and burns. Dry wood is highly flammable, which Plastic is an electrical insulator, which means it catches fire and burns easily, giving doesn’t conduct electricity. Both are off heat. useful in wire cables. Dry wood Copper wire lets catches fire electricity travel and burns through it. easily. Plastic stops Non-flammable electricity from stones stop leaking out of the fire from the cable. spreading. 157

Maya SEE ALSO ▸▸ Art p.28 The Maya people lived in Central America from 1000 bce ▸▸ Aztecs p.35 to 1600 ce. They built great cities from stone and farmed ▸▸ Farming p.98 maize, beans, and squash. The Maya had many gods, who ▸▸ Incas p.132 they built temples for. They were ▸▸ Games skilled mathematicians and developed a calendar. pp.240–241 ▸▸ Religion p.208 Mayan gods Mayan gods The Maya worshipped many different were often gods. They believed the gods shown wearing controlled the world around them, large hats including animals and the weather. decorated with holy symbols. Staircase Temple at leading to the top the top Mayan pyramid at Chichén Itzá, Mexico Chaac was shown with Temples the nose and fangs Many Mayan temples were built on top of a snake. of stone pyramids. Priests at the temples sacrificed animals, sang, and danced to Balls of incense honor the gods. were burned to honor Mayan sport the gods. The Mayans played a sacred ball game. Chaac was the Players hit a large rubber ball to different brother of the sun. parts of a court to win points. They could only use their forearms and hips. When he cried, his tears fell as rain. Chaac, the Mayan rain god 158

Measuring SEE ALSO ▸▸ Ancient Egypt We measure things to find a number that shows the size or amount of something. Being able to measure p.17 things lets us record and compare them. We use ▸▸ Astronomy p.32 many different types of measurements, as well ▸▸ Clocks p.61 as various tools for measuring. ▸▸ Earth p.83 ▸▸ Numbers p.185 Measuring tools Digital scales ▸▸ Volume p.269 for measuring Different tools let us measure time, size, weight Cup for distance, speed, weight, and volume. Volume measuring is the amount of three-dimensional space liquid something takes up. Clock for measuring time Different-sized cups for measuring cooking ingredients Thermometer Ruler for Spoons for for measuring measuring measuring temperature length small amounts of ingredients Weighing through history Big and small People have always wanted to be able to All objects can be measured one way compare amounts of things. The ancient or another. A box of eggs fits easily on Egyptians invented their own, very accurate weighing scales, but the Earth is system of weights and simple scales to so big it can only be weighed using measure the goods they bought and sold. complicated scientific calculations. A box of six Earth weighs eggs weighs 13.2 billion trillion about 10 oz lbs (5.9 trillion (300 g). trillion kg). 159

Medicine SEE ALSO ▸▸ Ancient Greece Medicine is used to treat and prevent sickness. Medicine can be made from plants or from chemicals in a science lab. p.18 Doctors are trained to discover different problems and find the right treatment or medicine to make people better. ▸▸ Biology p.38 ▸▸ Chemistry p.58 ▸▸ Human body p.130 ▸▸ Science p.217 ▸▸ Sickness p.225 Chamomile was Medieval medicine Medicinal leech used to treat fevers Too much blood was thought in ancient Greece. to make people sick, so leeches were used to suck out small amounts. Ancient medicine Plants and herbs have been used as medicine for thousands of years. Ancient Greek doctor Hippocrates was the first person to teach about medicine based on science. Early modern medicine This endoscope Doctors used new was used to inventions to find look inside ears. out what was wrong with patients. Bad This sickly royal Doctors smells were thought patient has been to cause sickness, so covered in leeches Doctors find out what is wrong patients breathed in to try to cure him. with patients by looking at nice smells like herbs. their bodies, asking questions, An X-ray takes and testing things from the A patient’s heart a picture of the body, such as the blood. could be heard with bones inside They can then treat them. the newly invented the body. stethoscope. Modern medicine Smallpox was Doctors use machines like the first infectious X-rays to look inside the body. disease to be wiped We know tiny germs and out by humans, in viruses cause sickness. We can kill germs with antibiotic 1980. medicines, and we can stop viruses with vaccine injections. 160

Mercury SEE ALSO ▸▸ Ancient Rome Mercury is the smallest planet in the solar system. Despite this, it can often be seen from Earth at sunrise p.20 and sunset. The average temperature is a scorching ▸▸ Asteroids p.30 332°F (167°C) because this planet is closest to the sun. ▸▸ Water pp.120–121 ▸▸ Moon p.171 Fast mover ▸▸ Solar system This planet takes its name p.233 from the speedy Roman ▸▸ Sun p.247 messenger god. Mercury moves faster across Earth’s Mercury is a dry, sky and faster around the rocky planet with sun than the other planets. no liquid water. Craters were made when asteroids hit Mercury billions of years ago. Large solar Temperatures panels kept on Mercury can soar MESSENGER working by to 800°F (430°C) turning the sun’s rays in the day and drop to into electricity. –290°F (–180°C) Exploring Mercury at night. Between 2011 and 2015, the robotic space probe MESSENGER Earth’s moon Tiny planet explored the surface of Mercury. The information collected Mercury Mercury is a very small allowed scientists to make 161 planet. It is only slightly complete maps of Mercury bigger than Earth’s moon. for the first time. The planets Jupiter and Saturn both have moons that are bigger than Mercury.

Metals SEE ALSO ▸▸ Bicycles p.36 We find metals in rocks. Metals can be strong or bendy, ▸▸ Elements p.90 and they let electricity pass through them. These features ▸▸ Iron Age p.140 are useful for making many things, from wires to buildings. ▸▸ Liquids p.148 Metals can be used on their own or mixed together. ▸▸ Magnets p.151 ▸▸ Meteorites p.164 Bicycle basics The ancient Brake levers Egyptians made are made of A bicycle is made from a long-lasting combination of strong and bendy things out of iron aluminum. metals. The type of metal used from meteorites, for each part depends on what it needs to do. which had fallen from space. Wheel rims are crafted from A strong titanium frame sturdy steel. does not rust. Steel spokes The chain is made Pedals are made support the from flexible of hardwearing wheel. carbon steel. aluminum. Metal from mines 2. Melting 3. Cooling The ore is heated to melt and The metal cools into a solid. It People dig tunnels underground remove the metal. Chemicals can be heated up and hammered to find metal in places called are added to help remove gases. into useful shapes. mines. Usually, the metal found in mines is not pure, which means it has rock and gas mixed in it. These materials need to be separated from the metal before we can use it. 1. Ore An ore is a rock that contains metal. The ore is discovered and dug out of the mine. 162

Metamorphosis SEE ALSO ▸▸ Amphibians p.15 Some animals go through amazing changes between birth ▸▸ Animal groups and adulthood. Their appearance changes so much that their fully grown shape is completely different to the p.22 newborn one. This process is called metamorphosis. ▸▸ Eggs p.86 ▸▸ Insects p.134 ▸▸ Life cycle p.146 Birth of a butterfly 2. Caterpillar Metamorphosis A hungry caterpillar is a Greek word Becoming a beautiful butterfly is a emerges from the egg. long process involving many stages It eats leaves and begins meaning and different forms. The process to grow. Although it takes between a month and a year. starts life small, the “change in caterpillar develops shape.” quickly. 1. Eggs 3. Chrysalis Butterflies start out as tiny The caterpillar wraps eggs, laid on plants. The itself in a protective layer size, shape, and color of the called a chrysalis. Inside, egg depends on the type of the caterpillar completely butterfly. changes its body shape. Frogspawn The chrysalis is Tadpole attached to a branch or leaf. 4. Butterfly Once the changes are complete, a butterfly emerges from the chrysalis. In a few hours, the butterfly can fly, and the life cycle begins again. Adult frog Froglet The chrysalis is left empty. Becoming a frog The wings need to The life cycle of a frog has many stages. A female dry out before the lays many eggs, called frogspawn, usually in butterfly can fly. water. These hatch into tiny tadpoles with gills for breathing. Tadpoles grow bigger and develop legs. Over a few more weeks, a froglet loses its tail, grows a frog’s tongue, and becomes an adult. 163

Meteorites SEE ALSO ▸▸ Asteroids p.30 Meteorites are pieces of space rock (asteroids and comets) that reach the surface of the Earth. They come in many ▸▸ Atmosphere p.33 different sizes, from tiny pebbles to rocks the size of a house. Only big meteorites can create craters when ▸▸ Comets p.68 they hit the ground. ▸▸ Metals p.162 ▸▸ Rocks and minerals p.214 ▸▸ Solar system p.233 Space rocks Stony-iron Meteroids are small Space Stony-iron pieces of asteroids Meteorites are made of meteorites are a and comets. materials that are also mixture of metal found on Earth. There and rock. They Asteroid The atmosphere are three main types. are very rare. Meteoroid is a layer of gases around the Earth. Stony Most meteorites Changing names Meteor Atmosphere that are found are stony. They come The name of a space rock Meteorite from the crusts of Earth asteroids. Iron changes as it approaches Iron meteorites are made of iron and nickel metals. Earth. In space, it is a They come from the cores of asteroids. meteoroid; in the atmosphere, it is a meteor; and on the ground, it is a meteorite. Crash site If a meteorite makes it through Earth’s atmosphere, it crashes into the surface. The hole it leaves is called an impact crater. This huge crater is found in Winslow, Arizona. 164

Microscopic life SEE ALSO ▸▸ Body cells p.41 Microorganisms are very tiny living things. They are all around us—in the air, in our bodies, and in water. Most ▸▸ Food chains microorganisms are so small that they can only be seen p.107 through a magnifying machine called a microscope. ▸▸ Inventions pp.136–137 ▸▸ Invertebrates p.139 ▸▸ Sickness p.225 Types of microscopic life Plankton Plankton are microscopic There are many kinds of microscopic plants and animals that life. Some are harmful and spread live in water. illness. Others are helpful, such as the bacteria in our stomach, Virus which break down our food. Viruses attack the cells of plants and animals, causing sickness. Bacteria Dust mites look Scientists put Microscope Some bacteria help our like tiny bugs. samples on glass bodies use food. Others slides to examine Microscopes use lenses cause illness, such as them in closer detail to enlarge, or magnify, cholera and tetanus. under a microscope. things. This lets us look at things much smaller Humans have Dust mites than what we can see with just our eyes. trillions of These microscopic bacteria bugs live all around us. They live in people’s in their bodies homes and eat to help them flakes of dead skin that drop off us. survive. 165

Migration SEE ALSO ▸▸ Birds p.39 Some animals make long journeys each year. These ▸▸ Insects p.134 journeys are called migrations. Animals migrate to find ▸▸ Mammals p.154 water, to spend winter in warmer places, or to find the ▸▸ Metamorphosis best place to mate and have their babies. p.163 Monarch butterfly North America ▸▸ North America Monarch butterflies fly p.184 thousands of miles to get ▸▸ Seasons p.221 from North America to Mexico. Butterflies that Summer arrive in Mexico hatch from Once the caterpillars have eggs laid by butterflies in turned into butterflies, North America. These live they are ready to fly farther until the spring, when they north in large groups, to can lay eggs on their own. mate and lay eggs. Key Autumn Spring Autumn The butterflies travel north As the temperature drops to lay their eggs in the warm spring air, and then die. and there is less food for the There will be plenty of leaves for the caterpillars Spring butterflies, the young ones to eat when they hatch. begin their long migration Summer south to warmer areas. Mexico Thousands Winter Arctic tern of butterflies Huge numbers of migrate butterflies come These small birds have the together. together in the forests longest migration of all in the winter to rest. animals. They fly back and Caribou forth between the North and South Pole areas. They fly for These hoofed animals eight months of every year. from the Arctic travel in enormous herds. They walk up to 30 miles (50 km) a day for three months to spend their summer in open areas and winter in forests. 166

Milky Way SEE ALSO ▸▸ Astronomy p.32 The Milky Way is a galaxy, or group of stars. It ▸▸ Constellations p.73 contains more than 200 million stars, including ▸▸ Earth p.83 our sun. Astronomers think that the Milky Way is ▸▸ Galaxies p.116 shaped like a spiral, with two main arms. ▸▸ Solar system p.233 ▸▸ Stars p.242 Home galaxy Scutum–Centaurus ▸▸ Universe p.263 Arm Our solar system is located The Milky Way about halfway between the will crash into another center and the edge of galaxy, the Andromeda the Milky Way. It turns around its center galaxy, in about once every 240 million years. 4 billion years. The center is The spiral shaped like a arms are long bar. made of stars, gas, and dust. Everything in the galaxy rotates Our solar system around its center. is located here, in a small arm called Edwin Hubble the Orion Spur. Edwin Hubble was a famous Perseus Arm American astronomer of the 20th century. He was the View from Earth first person to realize that there are other galaxies From Earth, we can see beyond the Milky Way. the Milky Way as a faint He also measured the white band across the distances between night sky. The light we galaxies. see is created by billions of shining stars. The Milky Way from Earth 167

Mixtures SEE ALSO ▸▸ Changing states A mixture is made when we mix different materials together and they can be easily separated back out into p.57 their original parts. Mixtures can be made from solids, liquids, and gases. There are three main ways of ▸▸ Gases p.117 separating mixtures. ▸▸ Liquids p.148 ▸▸ Rocks and minerals p.214 ▸▸ Solids p.234 Sifting Filtering We can use a sifter to separate large solids Filters are made from materials from small ones, or solids from liquids. A with tiny holes in them. The sifter is made from crisscrossed wire with small holes that let some solids through. holes catch solids that are too big to fit through, but The shells are let liquids pass. large solids that are caught by the sifter. Grains of sand A mixture of sand are tiny solids and water is poured that fall through into the filter. the sifter. The filter catches The liquid the sand but not changes to gas the water. and the solid will be left behind. The water that lands in the beaker has no Evaporation sand in it. Some solids such Compounds as salt dissolve (disappear) when they Some materials that are are mixed into a liquid. joined together can’t be If we heat the liquid, easily separated by sifting, we can take out the filtering, or evaporation. solid in a process These materials are not called evaporation. mixtures, they are compounds. Iron and Heat causes the sulfur make the liquid to boil and compound iron sulfide. change to gas. Iron sulfide 168

Money SEE ALSO ▸▸ Measuring p.159 We exchange money for things we want to buy, such ▸▸ Metals p.162 as food, clothes, and electricity. Money has a number ▸▸ Numbers p.185 value, and it is made up of coins and bills. Some objects ▸▸ Plastic p.195 are expensive and worth more money than others. ▸▸ Precious metals p.199 ▸▸ Work p.274 Currency Early currency A type of Digital money Before coins were shell that The different units invented, people was once Banks store money for people of money used around exchanged other widely traded. in bank accounts. People can the world are known as things as money, pay into or take money out of currency. In the US, including cattle, their bank account. They can for example, the currency salt, grain, and use a card or phone to is the dollar, and in Japan even shells. spend the money from the currency is the yen. the bank in a shop. Cowry shell Value Ancient coins n Dynasty coin An object that takes a lot of time to make or uses The first coins were used Chinese Ha expensive materials is said to have a high value. It nearly 3,000 years ago. Ancie will cost more money than something that is quick They were made from gold and easy to make and uses cheaper materials. and silver. Different coins were made across the nt Greek coin ancient world. Roman Emperor cient Egyptian c Antonius Pius. Danish krone Roman coin ean euros High-value sports car Low-value toy car An oin A springbok—the Ancient national animal of Modern money erican cent d South Africa. Europ Earning money Coins today are made th African ran from a mix of metals pence 169 People exchange their time for called alloys. We also British money, too. This vet gets paid use bills made n rupee for the time she spends making from cotton- animals better. She goes to work paper or plastic. and earns money. Am India Japa nese yen Vet at work Sou Mexican peso

Monkeys and apes SEE ALSO ▸▸ Africa p.12 Apes, monkeys, and lemurs belong to a group of animals ▸▸ Early humans p.82 called primates, which also includes humans. Most ▸▸ Habitats p.126 primates are smart and like to play. Primates are the only ▸▸ Rain forest p.204 animals with hands that can grab things. ▸▸ South America Apes p.236 ▸▸ Vertebrates Apes do not have tails and can stand more p.266 upright than monkeys. They use their huge, Old World strong arms to climb monkeys trees and hang from branches. From Africa and Asia, these monkeys live in many different places, such as swamps and mountain forests. Rhesus macaque Chimpanzee Chimpanzees Squirrel live in groups monkey 120of up to New World animals. monkeys From South America, these monkeys spend most of their time in the trees. They use their tails to swing from branch to branch. Lemurs Tool use Lemurs are only found Chimpanzees are some on the African island of of the smartest animals Madagascar. Most of in the world. They use them live in trees, and tools to open hard nuts are good climbers. or find insects to eat. Young chimpanzees Ring-tailed lemurs learn how to use tools from the older members of their group. 170

Moon SEE ALSO ▸▸ Asteroids p.30 The moon is a round, rocky, airless “body” that circles ▸▸ Atmosphere p.33 the Earth. It is the most familiar object in the sky after ▸▸ Comets p.68 the sun. People have visited the moon, but not ▸▸ Earth p.83 since 1972. ▸▸ Solar system p.233 ▸▸ Tides p.254 Rocky body The moon is large and rocky with a dusty, airless surface. It is about one-quarter the width of the Earth. The dark The moon’s surface is Man on the moon areas are covered with pits left where there by space rocks that The moon is the only object in used to be seas crashed into it. the solar system that has been of liquid rock. visited by humans. American Apollo space missions landed 12 Moon’s orbit people on the moon between 1969 and 1972. The moon travels around the Earth. This is called an Moon creation orbit. The moon takes 27.3 days to make its orbit Scientists think the moon was around our planet. created when a small planet, Theia, crashed into the Earth 4.5 billion years ago. As a result, rocks on the moon are similar to rocks on Earth. Moon The shape of the moon’s orbit Earth We always see the is a slightly squashed circle. same side of the moon facing Earth. 171

Mountains SEE ALSO ▸▸ Earth’s surface Mountains are tall, rocky features on the Earth’s surface. They usually have very steep sides and tower over the p.84 surrounding landscape. The tops of mountains are ▸▸ Evolution p.95 called summits, and they are often covered in snow, ▸▸ Glaciers p.122 even in summer. ▸▸ Rock cycle p.213 ▸▸ Rocks and Mountains around the world minerals p.214 ▸▸ Volcanoes p.268 Every continent has mountains. Most mountains are in rows, or Mountain life ranges, that can be thousands of miles long. Mountain animals must be able to survive on The Andes mountain steep rocks without range runs the length much oxygen to breathe. of South America. Mountain goats are good at climbing and eat small plants. The summit How are mountains made? This mountain is called the Matterhorn. It is part of a range Most mountains are formed over millions in Europe called the Alps. of years, as huge pieces of the Earth’s crust push into each other. Where they The treeline is the meet, the ground is forced up, making highest point on the mountain ranges. mountainside where trees can still grow. The pointed shape of the Matterhorn was made by slow-moving rivers of ice thousands of years ago. 172

Muscles SEE ALSO ▸▸ Body cells p.41 Muscles are stretchy cords that pull parts of the body to make them move. They work in teams. Some muscles work ▸▸ Feelings p.99 without us thinking, others move when we choose to move them. Every time we blink, smile, or move, it is with ▸▸ Human body the help of muscles. p.130 ▸▸ Skeleton p.228 ▸▸ Sports p.239 ▸▸ Games pp.240–241 Muscular system Bicep muscle Most of our muscles are wrapped around the bones of our skeletons, forming the muscular system. They move our bodies by pulling on the bones. Tricep muscle Muscles are Working in pairs attached to Muscles only pull—they bones by can’t push. To lift your arm tendons. up, biceps pull and triceps relax. When triceps pull and biceps relax, the arm moves back down again. The biggest Stomach Face muscles muscle in our muscles are body is in our called abs. The muscles in our face move the eyes bottom. It is and mouth and help us to express our called the Upper thigh feelings to others. For example, we gluteus muscles are show we are happy by smiling. maximus. called quads. 300You use Exercise different muscles The more we move our just to stand up. muscles, the stronger they get. After exercise, the body repairs any damage to muscle cells by making new muscle fibers. This is why muscles become bigger and stronger the more you use them. 173

Mushrooms SEE ALSO ▸▸ Animal groups A mushroom is the fruit of a fungus. Fungi are neither animals nor plants. They feed on living and dead animals p.22 and plants. Many fungi are very poisonous—you should not touch or pick them. ▸▸ Color pp.26—27 ▸▸ Fruit and seeds p.115 ▸▸ Life cycle p.146 ▸▸ Plants p.194 Fly agaric Cap This is the head of Parts of a mushroom the mushroom. It protects the gills. Mushrooms scatter tiny, seed-like spores, so that Gills All parts of the fungi can spread. Many These delicate fly agaric mushroom are brightly colored. structures hold the mushroom’s spores. are poisonous. It Ring This protects the was used to kill flies gills. It breaks away in medieval times. as the cap grows. Fungi There are many different types of fungus. Most of them grow in damp places, such as grassy fields and shady woodlands. Stem Devil’s fingers Green elfcup Yellow jelly antler This supports the cap and supplies the mushroom Spores with the water and food it needs to stay alive. Spores are tiny cells from which new fungi grow. They Roots are released into the wind These underground when a fungus bursts open. tubes collect water The spores are carried away and food. in the wind. When they fall, they can grow into new fungi. Puffball 174

Musical instruments SEE ALSO ▸▸ Dance p.76 An object used to make musical sounds is called a musical ▸▸ Hearing p.127 instrument. Musical instruments make sounds in different ▸▸ Music ways—some have strings that vibrate, others a hole to blow into or a surface to beat. We put musical instruments pp.176–177 into four groups based on how they make sound. ▸▸ Orchestra p.188 ▸▸ Radio p.203 ▸▸ Sound p.235 Strings Wind The sound of stringed instruments Wind instruments such as the trumpet comes from their vibrating strings. or flute are made of tubes of wood or Players pluck the strings with their metal, which might be straight or fingers or move a bow across them. looped. Musicians play wind instruments by blowing into them. Drawing a horsehair bow over the violin’s strings makes them vibrate. Keyboard Pressing valves on a trumpet changes Musicians play instruments such as the tube’s length pianos and synthesizers by pressing to make a higher keys on a keyboard. Piano keys or lower sound. cause a tiny hammer to hit a string, which produces a particular Percussion sound called a note. Percussion instruments such as A modern drums make a sound when they grand piano are hit. Some, such as bells and has 88 keys. xylophones, can make different notes (sounds). Others, such as rattles, produce a noise when shaken. Traditional drum heads are made from animal skin. 175

The story of... Musicians Playing together rehearsing Music in Brazil Many people enjoy getting together to make music. Since the earliest times, people have felt the need to make music. We can express our feelings Players and singers perform by singing or playing instruments. Musicians in concerts or just for fun. organize sound into tunes and regular patterns known as rhythms. A steady rhythm can inspire people to dance. Classical music The American Pop and rock This part Symphony changes the Most music performed in Orchestra Most of the music we hear vibrations of the concert halls is known as classical performs in on the radio is rock or pop music. strings into an music. It is played by orchestras or New York Before pop music, most music was electric signal. classical or traditional. Pop music groups of musicians called introduced electronic instruments, a ensembles, and sung by choirs. strong beat, and words that are easy Classical music began hundreds to sing along to. It quickly became of years ago, but is still popular all over the world. written, played, and enjoyed today. Singing Singing is an important part of music-making all over the world. Singing helps us to express our feelings. A singer can sing alone, or with others as part of a choir. 176

Kalengo drum First instruments from Nigeria The first instruments were Around the world probably rattles and drums There are different types of made of wood or bone. music and musical instruments all Instruments that make a over the world. Singing styles are sound when you blow them varied too. African music is often very rhythmic and exciting, while appeared more than 40,000 years ago. Asian music emphasizes the tune. Bone flute from around 800 bce Pan flute Guiro from from South Central America America The longer the The sound the guitar pipe, the lower makes is created by the sound turning these knobs, it makes. which tighten or loosen the strings. Notes can be made by pressing the string on the fingerboard and plucking the strings further down. Gibson 1932 Modern sounds electric guitar The year the first The first musical instruments electric guitar made sounds when people was sold. touched or blew them. Now we also have instruments powered by Notation electricity. Modern synthesizers can copy other instruments Musicians write music down using a and make completely system of symbols called new sounds too. musical notation. The dots This is the music on and between the lines Synthesizer for “Twinkle Twinkle tell the performer which Little Star.” notes to play or sing. 177

Myths and legends SEE ALSO ▸▸ Ancient Egypt Myths and legends are stories. In the past, people invented myths to answer big questions, such as where p.17 our world came from. Unlike myths, legends are often based on real events, but the details have changed a lot ▸▸ Ancient Greece over time, so there is not much truth left! p.18 ▸▸ Storytelling pp.42–43 ▸▸ Books p.44 ▸▸ Writing p.280 Mythical creatures Legendary heroes Myths often include strange creatures, Many myths and legends tell which sometimes have a mix of features from the stories of brave people different animals. Mythical creatures can be called heroes. Hua Mulan is terrifying monsters, or friendly beasts like the the hero of a Chinese legend. Chinese dragon. She pretends to be a man and takes her elderly Minotaur father’s place as a soldier. The minotaur is a scary monster with This is a modern statue a human body and of Hua Mulan. Her story the head of a bull. has been told in many He appears in an books and films. ancient Greek myth. Chinese dragon “Myth” comes The Chinese dragon from the Greek has four legs and a word “mythos,” long, snakelike body. In China, dragons are a which simply symbol of good luck. means “story.” Griffin The griffin is part lion 178 and part eagle. In Greek myths, griffins stand guard over treasures. Creation myth Many myths are about how the world was created. An Egyptian myth says that the first people in the world were shaped out of clay on a potter’s wheel, by a ram-headed god called Khnum.

Native Americans SEE ALSO ▸▸ Arctic p.25 People first moved from Asia into the Americas more than 25,000 years ago. When Europeans first arrived in ▸▸ Art p.28 the Americas in the late 1400s, there are thought to have been 50 million people already living there in tribes. ▸▸ Dance p.76 These people are known as Native Americans. ▸▸ North America p.184 ▸▸ Religion p.208 ▸▸ Homes pp.244–245 The center Cultural areas of this mask shows the There were once hundreds of Native sun god. American tribes, each with its own traditions. This map shows the ten Native American cultural areas. The tribes of each area often shared similar customs or ways of life. Art and beliefs By the early KEY Southeast Plateau Southwest Native Americans had many gods and beliefs. 16th century, Northwest Plains Some rituals involved dance, and people Arctic Great Basin often expressed their beliefs through art. the Native American Subarctic California For example, the Bella Coola tribe used this population had fallen to Northeast carved mask for dance ceremonies. only 400,000 Finding food due to disease Some tribes grew crops such as potatoes, corn, brought by the or tomatoes. Other tribes relied on hunting wild animals, such as buffalo, or gathering plants. Europeans. Homes Native Americans lived in different kinds of homes. Northeast farmers had longhouses, which were homes built for several families. Plains hunters used tents called tepees. 179

The story of... Leaving Africa Exploration Humans first lived in Africa. They started to leave this continent in large Humans have explored the land, groups between 80,000 and 70,000 years ago. sea, and sky, and we are starting They went by foot to the nearby continent of Asia, to explore space. Since our first travels on land, we have made and later traveled by boat to Australia. new technology to let us sail and fly. Distant countries can ASIA NORTH work together because of AMERICA world exploration. We might EUROPE even live in space one day! AFRICA The first people SOUTH lived in Africa. They AMERICA slowly spread around the world. AUSTRALIA Ginger Trade In the past, people Vasco da Gama traveled many miles by land and sea to buy things found the first from other countries. Merchants sea route from found new routes between distant lands, and bought or Europe to India in traded items such as spices. the 15th century. These goods were then brought home to sell. Cinnamon Cloves Reaching This ship carried The Santa Maria the poles Christopher Columbus to an island off the coast The freezing North of America in 1492. and South poles were unexplored until the early 1900s. The first explorers traveled in sleds pulled by dogs and wore fur for warmth. American explorer Robert Peary, in 1909 180

Some deep-sea Under the sea 200fish live for more than years. Oceans are many miles deep in places. Age of A deep-sea hatchet fish These black depths exploration are largely unexplored. Around The few crafts that In the 1400s, Europeans the world have reached the traveled by ship to distant bottom of ocean places they had never been As technology advances, trenches have found to before, including America. new opportunities for mysterious new creatures. These long trips were exploration open up. The first flight called expeditions. around the world was made in 1924 Solar cells on the by a plane that ran on fuel. In 2016, wings of Solar Wind blew into Impulse 2 use the sails to power Solar Impulse 2 made the first sunlight to power the ship. around-the-world flight using the plane. sunlight converted into power. In 1961, Yuri Gagarin became the first man in space. Europeans first Space sailed all the way exploration to Australia in the A Russian spacecraft 17th century. called Sputnik 1 first flew around the Earth in 1957. Humans soon made it into space, too, and landed on the moon in 1969. Since then, we’ve used robots to visit every planet in the solar system, as well as comets. 181

Navigation SEE ALSO ▸▸ Compass p.70 Navigation is finding where you are and where you are ▸▸ Constellations going. We can use the sun, stars, a compass, and paper maps to navigate. Today, most modern transportation p.73 receives signals from satellites in space to show where ▸▸ Light p.147 it is on Earth. This is called GPS. ▸▸ Maps p.155 ▸▸ Radio p.203 How does GPS work? ▸▸ Satellites p.215 The Global Positioning System (GPS) 3. Signal speed uses signals from a group of The satellite signals are sent satellites in space to work out as radio waves. The phone exact locations on Earth. can tell how far the signal has traveled by how long the signal has taken to reach it. 1. Orbiting satellites 2. Location and time 4. Mobile phone Satellites go in a steady The satellite sends out a The mobile phone circle around the Earth. signal that includes where works out where There are always at least it is and the exact time. it is on Earth by four GPS satellites in looking at how range of your phone. far it is from each of the Latitude lines Longitude lines four satellites. run across. run up and down. Map and compass Latitude and 90˚ longitude 60˚ Without GPS, we can still navigate 30˚ using a paper map and a compass. Maps of Earth have grid 0˚ The compass shows the lines of latitude and direction North, which longitude to show 30˚ helps us work out where places are. Every which direction we place has a unique need to go. latitude and longitude number in degrees. 90˚ 60˚ 30˚ 0˚ 182

Neptune SEE ALSO ▸▸ Atmosphere p.33 Neptune lies in the freezing cold, dark outer parts of the ▸▸ Gases p.117 solar system. It is the eighth planet and the farthest planet ▸▸ Liquids p.148 from the sun. Neptune is often called the “twin planet” of ▸▸ Pluto p.196 Uranus because it is made up of similar ices and gases. It is ▸▸ Solar system four times larger than Earth. p.233 ▸▸ Uranus p.264 Wispy clouds made The windy planet of frozen methane gas are found high Neptune is known as “the windy planet” in Neptune’s because it has powerful winds in the atmosphere. outer layers of its atmosphere. Winds can reach speeds of more than 1,500 mph (2,400 kph), about twice the speed of sound. Neptune gets its blue color from methane gas in the upper atmosphere. Hydrogen and Scientists think helium gases that Neptune’s largest make up most of Neptune’s moon Triton is an icy atmosphere. minor planet God of the sea that got caught by Neptune’s gravity. Neptune was named after the Roman god of the sea, who is The sun usually pictured carrying a three-pronged spear called a Beyond Neptune trident. The planets Mercury, Venus, Mars, Jupiter, and There are thought to Saturn are also named after be several thousand icy Roman gods. “minor planets” that orbit the sun beyond Neptune. The first, and largest, minor planet that was discovered is Pluto. 183

North America SEE ALSO ▸▸ American West North America stretches from the icy Arctic in the north to tropical Central America in the south. Huge areas of p.14 grassland, called prairies, cover much of North America. There are also mountains, forests, deserts, and some ▸▸ Arctic p.25 of the world’s biggest lakes. ▸▸ Aztecs p.35 ▸▸ Native Americans p.179 ▸▸ South America p.236 Alaskan salmon Grizzly bear About Inuit Polar bear North drummers Moose America Totem Rocky Beaver The moose is the Population: Mountains largest member 579 million pole Wheat of the deer family. Yellowstone is on top of a Canadian huge volcano Mountie known as a supervolcano. Highest point: Yellowstone Denali National Statue of Lowest point: Badwater Basin Park Mount Liberty The United Biggest desert: Rushmore States is home to Great Basin Desert The White House the remains of more Grand types of dinosaur Canyon than any other Hollywood Monarch butterfly country. Mississippi River Kennedy Space Center Armadillo Longest river: Pico de Baird’s Every year, 14,000 Missouri Orizaba tapir ships pass through the volcano Panama Canal, which Statue of Liberty links the Pacific and Mississippi River Atlantic oceans. This statue towers 305 ft (93 m) over The Mississippi is a huge river Panama New York Harbor. in North America. Ships use it Canal Completed in 1886, for transporting goods, and it was a gift from the tourists ride on its riverboats people of France called paddle steamers. to the people of the US. 184

Numbers SEE ALSO ▸▸ Clocks p.61 Numbers are symbols that can be used to show amounts, ▸▸ Coding p.65 sizes, distances, and times. The ordinary numbers we ▸▸ Codes pp.66–67 count with are called ”whole numbers” or ”natural ▸▸ Fractions p.112 numbers.” All math requires us to use numbers. ▸▸ Measuring p.159 ▸▸ Temperature p.252 Whole numbers 0 1 23 The numbers 0 to 9 are used to build all the bigger numbers. They are called whole numbers because they are not split into smaller amounts. Zero represents Whole numbers are nothing. also called “positive” numbers. Negative numbers -5 -4 -3 -2 -1 0 1 2 3 4 5 Numbers less than zero are called \"negative\" Negative numbers Zero is neither Positive numbers numbers. They are are shown with positive nor have no symbol used to show things a minus sign. negative. in front. less than zero, such as cold temperatures. Algebra Place value 2 Algebra is a type of math that uses letters to stand The place where a number is written in a for numbers or amounts. We can use algebra to longer number shows how much it is worth. work out the value of unknown amounts. 4 , 5 6The lowest worth, the unit, is on the right. 2+a=5 The “a” represents An equals sign Thousands Hundreds Tens Units a mystery number. means both This shows how This shows how This shows how Units are We can work out sides of the many thousands many hundreds many tens the numbers what it is by taking equation have the number has. the number has. from 0–9. 2 away from 5. the same value. number has. 185

Oceania SEE ALSO ▸▸ Asia p.29 Oceania is a continent made up of Australia, New Zealand, ▸▸ Birds p.39 Papua New Guinea, Fiji, and other islands in the tropical ▸▸ Coral reefs p.74 Pacific Ocean. It is home to some of the world’s most ▸▸ Deserts p.78 unusual wildlife, including kangaroos, koalas, duck-billed ▸▸ Mammals p.154 platypuses, and kiwis. ▸▸ Sports p.239 ▸▸ World p.275 This island, called Male birds of paradise New Guinea, is have brightly colored split between feathers, which they Oceania and Asia. show off to female birds. Bird of paradise Great white Blue-winged Duck-billed Seahorse shark kookaburra platypus Wombat Great Barrier About Reef Oceania Dingo Saltwater Population: crocodile 40.3 million Dolphin The Great Barrier Reef is made up Uluru of nearly 3,000 coral reefs. Witchetty Redback Koala grubs spider Opal Cricket These caterpillars live Surfing Kiwi Highest point: underground, where they Mount Wilhelm eat roots. They can grow Three Sisters to 4 7/10 in (12 cm) long. rocks Australian rules football Mount Taranaki This fierce dog-sized Sperm whale Lowest point: meat-eater lives Lake Eyre only in Tasmania. Tasmanian devil Uluru All Blacks Biggest desert: rugby team Great Victoria This giant sandstone rock feature towers over Desert the landscape of central Australia. Uluru is a special The kiwi uses Longest river: place for the aboriginal its strong legs Murray people who have lived for running in Australia for thousands and fighting. Kiwis of years. The kiwi is a flightless bird that lives in New Zealand. It is about the same size as a chicken, but its egg is six times the size of a chicken’s egg. 186

Oceans and seas SEE ALSO ▸▸ Coral reefs p.74 More than two-thirds of our planet is covered by oceans ▸▸ Water and smaller seas. They contain most of the world’s water and are full of life of all shapes and sizes. Some of the pp.120–121 deepest parts of the ocean have still not been explored. ▸▸ Exploration Ocean depths Sunlit zone pp.180–181 This zone receives ▸▸ Seashore p.220 Oceans are divided into different zones lots of sunlight and is ▸▸ Tides p.254 according to depth. The deepest part is the layer of the ocean more than 6 miles (10 km) that contains most Arctic Ocean beneath the surface. plants and animals. Pacific Atlantic Pacific Ocean Ocean Ocean Indian Ocean Southern Ocean Twilight The world’s oceans zone The Earth has five oceans. The largest Little sunlight reaches is the Pacific, which holds half of the the twilight zone. Many world’s salt water. The smallest is the creatures that live here Arctic Ocean, which is partly frozen. have body parts that glow in the dark. Dark zone Ocean smokers The dark zone is deeper than 3,300 ft In places, hot water bursts from the (1,000 m). The water is seabed, creating chimneylike structures dark apart from some known as smokers. The water that comes animals that glow out from the smokers can be white or black, depending on what minerals the with light. water around them contains. Deep-sea zone In the deepest part of the ocean, weird creatures live in total darkness. 187

Orchestra SEE ALSO ▸▸ Dance p.76 An orchestra is a large group of people playing different ▸▸ Film p.100 musical instruments together. Orchestras were created ▸▸ Musical to play classical music, such as complicated pieces called symphonies. Orchestras often create music for films, and instruments sometimes play non-classical pieces, such as pop music. p.175 ▸▸ Music pp.176–177 Classical Cymbals Glockenspiel Timpani ▸▸ Radio p.203 orchestra Trumpet Trombone ▸▸ Sound p.235 A classical orchestra is French Gong split into four sections: horn strings, woodwind, brass, Tuba and percussion. It is led by a person called a Double conductor. bass Flute Clarinet Oboe Bassoon Viola Violin Sections Conductor Cello Strings Woodwind Conductor Brass Percussion Every classical Many classical Using hand Full orchestras There are many orchestra has orchestras gestures and a include a brass percussion stringed instruments. include instruments of stick called a baton, the section, which is usually instruments. Percussion These are usually two the woodwind family, conductor makes sure behind the woodwind. usually seen in a classical groups of violins, as well such as flutes and the musicians play Trumpets, trombones, orchestra includes the as violas, cellos, and bassoons. They usually together at the right French horns, and tubas timpani, bass and side double basses. sit behind the strings. time and speed. are brass instruments. drums, and cymbals. Playing together The gamelan Chinese orchestra In Java and Bali, people play percussion A Chinese orchestra There are different types of instruments, such as xylophones, in an uses traditional orchestras around the world. orchestra called a gamelan. Chinese instruments. They often use very different There are woodwind, instruments from the classical percussion, and orchestra, and might have stringed sections. fewer people playing. Chinese gong 188

Philosophy SEE ALSO ▸▸ Ancient China Philosophy is a way of trying to understand things by asking questions and thinking of answers. It was first p.16 studied thousands of years ago, when people wanted to find out about the world and their own lives. People who ▸▸ Ancient Greece try to find answers to these questions are known p.18 as philosophers. ▸▸ Governments p.123 ▸▸ Religion p.208 ▸▸ Science p.217 Asking questions Thinking of answers To find out about the world, Philosophers try to come philosophers ask all sorts of up with answers to these questions. They ask about things questions. By thinking hard such as what is real around us, and about their answers, they can what is the best way to live decide whether they are our lives. true or false. What makes How do I me who know what I am? is true? Why do things exist? Right and wrong Equality First philosophers An important part of philosophy is Men and women are often treated deciding what makes something right differently. For example, men are generally Western philosophy began or wrong. For example, we all know paid more. Philosophers try to explain how in ancient Greece. The that stealing is bad. Philosophers ask everybody should be treated equally Greek city of Athens why it is bad. (the same). was home to many of the most important early philosophers, such as Socrates, Plato, and Aristotle. Statue of Plato 189

Photography SEE ALSO ▸▸ Art p.28 A photograph is a still image taken using a machine called ▸▸ Computers p.71 a camera. Photographs give us a visual record of who we ▸▸ Film p.100 are and what we have done. These images can capture ▸▸ Inventions important people and events in history, or private moments in your own life. pp.136–137 ▸▸ Telephones Cameras Early cameras The first cameras took p.250 The first photographic pictures on metal ▸▸ Television p.251 cameras were invented sheets that had been in France in the 1800s, made sensitive to light. Taking pictures but were large and hard It took many minutes to use. Cameras are to take a photo. Photographs fall under now small enough to fit different categories called inside mobile phones. genres. Pictures you take of yourself are called These cameras can selfies, and other genres connect to computers include animals and travel. to transfer images. Daguerreotype cameras were the first cameras to go on sale to the public in 1839. Digital camera Film camera Selfie Modern digital cameras Later cameras use produce images made The film is strips of light-sensitive up of millions of tiny rolled up plastic film. When the points of color that are inside the film is exposed to light, displayed on screens. camera. a picture forms. Pet portrait The first Camera phone photograph was Many people now take photographs using tiny digital cameras built into their taken in 1816 by mobile phones. These photos can also be French inventor transferred to and viewed on computers. Nicéphore 190 Niépce. Vacation snap

Photosynthesis SEE ALSO ▸▸ Carbon cycle Plants make their own food. They do this by taking in the sun’s light energy, as well as water from the p.49 ground and gas from the air. Producing energy in ▸▸ Cells p.56 this way is called photosynthesis. ▸▸ Gases p.117 ▸▸ Light p.147 How do plants ▸▸ Plants p.194 make food? ▸▸ Temperature The plant combines carbon p.252 dioxide with water to make sugar. The energy it needs Sunlight to do this is supplied by Plants need energy from the sun’s light. sunlight to complete photosynthesis. They The oxygen that grow toward the light. plants give out is Carbon dioxide the same gas that Holes in the plant’s leaves take in a gas called carbon dioxide. humans and animals need Oxygen Oxygen is released as to breathe in. waste when carbon dioxide, water, and light react together in the plant. Conditions Temperature, light, and water need to be just right for a plant to survive. If these conditions change too much and don’t suit the plant it will start to die. Leaves droop. Leaves The stem is strong Leaves turn A chemical in the leaves to support the brown. called chlorophyll absorbs plant and move it light energy from the sun. toward light. Water Chlorophyll makes plants The plant needs look green. water to survive. Water travels up the stem into the plant. Roots Without light Without water The plant roots take in water and minerals from the soil. 191

Physics SEE ALSO ▸▸ Circuits p.59 Everything in the universe that weighs something is ▸▸ Electricity p.87 called “matter.” Physics is a science that looks at how ▸▸ Energy pp.88–89 matter moves and interacts. This includes energy, ▸▸ Forces p.108 forces, magnets, light, heat, waves, and sound. ▸▸ Magnets p.151 ▸▸ The sciences pp.218–219 Understanding Medical equipment weather Scanners, heart Physics lets us predict monitors, and X-ray weather, by studying machines were all how patterns of heat invented by people and cold create wind. using physics. Nuclear physics Atoms are the tiny Weather balloons particles that everything collect weather is made from. Splitting them releases energy information we can use. Heart rate monitor Computers Tiny wires connect parts Diagram of Circuit board from an atom inside a computer inside machines and computers so that they can carry out tasks. Physics around us Discoveries from physics are used in everyday life. This is called applied physics. Solar panels collect energy from the sun Electricity Fairground Mechanics We can make ride Studying pushes, electricity by burning pulls, and movement fuel or using heat, 192 sunlight, wind, lets us design machines, including or water. fairground rides.

Pirates SEE ALSO ▸▸ Clothing Pirates were criminals who attacked ships to steal goods, using force and violence to get their way. They are often pp.62–63 now remembered as jolly villains who buried treasure ▸▸ Explorers p.96 and relaxed on tropical islands, but ▸▸ Flags p.102 the reality was not so pleasant. ▸▸ Maps p.155 ▸▸ Oceans and seas Large hats kept pirates sheltered p.187 from the sun and rain. ▸▸ Ships p.224 Pirate life Pirates could be at sea for weeks at a time. To keep from getting irritable, which could lead to fights among the crew, they passed the time with music, games, food, and drink. Pirate flag Clothes were The years between made of wool, Pirates put symbols of death on linen, and 1690 and 1725 their flags to frighten people. These canvas. symbols included skulls, bones, and are known as the skeletons. This flag was flown by famous pirate Jeremiah Cocklyn. golden age of piracy. Pirate ship Swords called Pirate ships had to cutlasses had short, be fast so they could curved blades. catch other ships or escape from trouble. Blackbeard They were armed with cannons for The most famous pirate of all fighting. This type was nicknamed Blackbeard. of ship is called He attacked ships on the a sloop. American coast until he was finally killed in a battle with the British Navy in 1718. Large sails Leather shoes helped the ship closed with move quickly. small brass buckles. 193

Plants SEE ALSO ▸▸ Flowers p.103 Plants are living things that make their own ▸▸ Food p.106 food using energy from the sun. Most ▸▸ Fruit and seeds plants stay in one place, with roots that fix them in the ground. p.115 ▸▸ Insects p.134 Types of plants Flowers produce ▸▸ Photosynthesis seeds, which grow There are four main groups of plants. into new plants. p.191 Some have flowers, like hibiscus. Others ▸▸ Trees p.261 don’t, such as conifers and mosses. Before a flower opens, Conifer Flowering plant it is called a bud. Plants that have Most plants have seeds in cones flowers, which Leaves make the food are called make seeds. that keeps plants alive conifers. They and helps them grow. are mainly trees. The stem helps keep Moss Fern the plant upright. It also These leafy plants grow Ferns don’t have flowers. transports water and where it is damp and dark. Their leaves start off very minerals to the leaves. small and uncurl as they grow. Plants are Meat-eating plants the only living Some plants get extra energy by catching and eating things that live animals, such as insects. Some even catch frogs! The plant shown here is called a Venus flytrap. on every continent. Sweet nectar The insect’s The plant lures the insect weight makes squeezes all Roots anchor the into the plant. the trap shut. the juices out plant in the soil. of the insect. Tiny hairs on the plant’s roots take in minerals and water from the soil. Hibiscus plant 194

Plastic SEE ALSO ▸▸ Atoms p.34 Plastic is a useful material that we make, but it can also be ▸▸ Carbon cycle p.49 found naturally. It can be colored and molded into shapes ▸▸ Electricity p.87 without breaking. It is waterproof, so it can be used for ▸▸ Gases p.117 packaging and to carry liquid. It’s also strong enough to ▸▸ Liquids p.148 make rope. ▸▸ Materials p.157 ▸▸ Recycling p.205 Plastic everywhere Plastic containers are waterproof Useful plastic We use plastic to make to carry liquids. many everyday objects, Plastic is a useful including toys, glue, cars, Liquid plastic Plastic can be material because of how bags, computers, tents, can be poured see-through, it behaves. For example, and clothes like fleeces and into interesting so we know it doesn’t let electricity raincoats. For most items, molds. what’s inside. through, and is strong the plastic is heated to and long-lasting. become liquid, then poured into molds to set. Electric cable Tough and Insulation hard-to-break Plastic is an insulator, which plastic is means electricity and heat useful in toys. can’t flow through it. It keeps electricity inside cables. Laboratory containers Smooth plastic is Plastic rope is Plastic lenses Hard to break used for things we flexible and strong. in glasses are Plastic containers are harder need to hold on to. harder to break to break than glass or pottery Making plastic than glass. ones. They are also easier to 25 make and safer to use. Natural plastic is found in plants, plastic bottles can be trees, insects, animal horns, and milk. Plastic recycled to make one Artificial plastic is made from oil, coal, bags and natural gas found underground. polyester fleece. All plastic contains an element Long-lasting called carbon. Plastic lasts a long time. It can Plastic pellets build up in the environment, 195 so we turn it into new plastic by recycling it.

Pluto SEE ALSO ▸▸ Earth’s surface Pluto is a dwarf planet that travels around the sun at the edge of our solar system, beyond Neptune. It has p.84 one giant moon called Charon, and four small moons. ▸▸ Glaciers p.122 Pluto’s surface is covered ▸▸ Moon p.171 with ice. ▸▸ Neptune p.183 ▸▸ Solar system p.233 ▸▸ Volcanoes p.268 Ex-planet Pluto used to be considered the ninth planet in our solar system. When other similar small “planets” were discovered, astronomers downgraded Pluto to a dwarf planet. Ice volcanoes Pluto may have cryovolcanoes— volcanoes that erupt an icy slush of water and gases. Pluto A feature known as Wright Mons is thought to be a cryovolcano. Dwarf planets Dwarf planets are similar to planets but smaller, which means they share their path around the sun with Moon other objects, such as asteroids Pluto’s orbit Pluto’s and comets. Pluto travels around the sun at a different orbit angle to the planets. Its orbit is shaped like an elongated circle. It takes Pluto 248 Ceres Makemake Huamea Pluto Eris Earth years to circle the sun. 196

Polar habitats SEE ALSO ▸▸ Animal groups Polar habitats are snow- or ice-covered areas found in the coldest places on Earth—the Arctic in the north p.22 and Antarctic in the south. There are no trees and only very few plants. Animals have to survive in ▸▸ Antarctica p.24 freezing temperatures. ▸▸ Arctic p.25 ▸▸ Earth p.83 ▸▸ Habitats p.126 ▸▸ Oceans and seas p.187 Arctic Antarctic Around the North Pole at the top of the world is Around the South Pole at the bottom of the world the frozen Arctic Ocean. The Arctic also includes is the large landmass, or continent, of Antarctica. the northern tips of Canada, Russia, Greenland, The Antarctic is the coldest and windiest place on and Norway. Earth. It has no large land animals. Arctic skuas often Snowy owls have Wandering albatrosses chase other birds thick feathers to have the widest to steal their food. keep them warm. wingspan of all birds. Reindeer walk Emperor penguins Chinstrap penguins long distances in huddle together for live in large search of food. warmth in the winter. groups, called colonies. Polar bears have thick fur coats to An iceberg is a chunk keep them warm. of floating ice. Most of it is underwater. Animals use pieces of floating ice to Weddell seals take a rest. have thick layers of fat to keep Walruses use their Southern elephant them warm in the tusks for fighting seals catch krill, cold water. and pulling fish, and squid in themselves the cold ocean. onto the ice. Arctic Ocean Male narwhals Southern minke Southern Ocean In the center of the Arctic Ocean have a long tooth. whales use their beak Around Antarctica, the is a gigantic piece of ice that Narwhals eat squid to make holes in the Southern Ocean is very cold. never melts. The icy water and large fish. ice for breathing air. Huge chunks of ice, called around it is full of fish and squid. icebergs, float in the water. 197

Pollution SEE ALSO ▸▸ Cars p.52 Pollution happens when dirty or harmful substances are released into the world around us. Pollution kills ▸▸ Climate change wildlife, causes health problems for humans, spoils the p.60 countryside, and makes the world around us dirty. It is even making our planet warmer. ▸▸ Factories p.97 Air pollution ▸▸ Farming p.98 Cars, trucks, factories, ▸▸ Industrial and power stations Revolution p.133 pump out gases into the ▸▸ Recycling p.205 air. These can cause illness, poison rivers and oceans, and heat up our world. Land pollution Poisons from garbage dumps seep into the ground and then into rivers. Chemicals used in farming kill insects, such as bees, and can make people ill. Water pollution Great Pacific Plastic garbage is garbage patch washed into the sea and swallowed by sea life. Harmful waste from factories and sewage from homes pollute rivers and sea water. Garbage at sea When waste plastic is dumped in the sea, it is carried away by currents into gigantic, floating garbage patches. The biggest patch is in the North Pacific Ocean. It is called the Great Pacific garbage patch and is bigger than the US. 198