DK Children’s Encyclopedia)_clone

Carbon cycle SEE ALSO ▸▸ Atmosphere p.33 Without the element called carbon, our world would be ▸▸ Climate change frozen and lifeless. Carbon constantly moves between living things, the atmosphere, the oceans, and the Earth p.60 below us. This movement is known as the carbon cycle. ▸▸ Elements p.90 ▸▸ Fossil fuels p.110 ▸▸ Gases p.117 ▸▸ Pollution p.198 Carbon Carbon floats in CO2 is released into movement the atmosphere as the atmosphere carbon dioxide (CO₂). by factories. Carbon is always on the move. When Animals it is in the air, it is breathe combined with oxygen out CO2. to make the gas carbon dioxide (CO2). Plants use sunlight Plants take and CO2 to make in more CO2 their own food. than they give out. Oceans take in CO2. 17% Animals take Carbon from dead other in carbon when sea life is released elements they eat plants. as CO2, or forms rocks or fossil 18% Animals release fuels such as oil. carbon CO2 when they die or poo. CO2 is released from fossil 65% fuels whenthey are dug oxygen Dead plants up and burned. rot or eventually become fossil fuels such as coal. Carbon in Keeping the Sun the human body Earth warm Some sunlight Almost one-fifth of the Carbon dioxide in the is reflected, and human body is made of atmosphere acts like a some is trapped carbon. After we die, this blanket around the Earth, as heat by CO₂. is returned to the Earth trapping the sun’s heat. and naturally recycled. Without it, the Earth Earth’s would be very cold. atmosphere 49

The story of... Earth is born Changing world Our planet was formed when rocks orbiting the sun Since it formed, the Earth has been crashed into each other and covered with molten lava, bombarded stuck together. The early Earth by rocks from space, and blanketed had a poisonous atmosphere in ice. In 4.5 billion years, the Earth has changed from a hot, and a volcanic landscape lifeless planet into a watery with lots of craters. home, full of life. The formation On the move of the Earth Earth’s land is split up into Mountains are huge chunks called continents. Throughout Earth’s history, the created when continents have shifted around. continents Today, there are seven move and hit continents, but they have not always looked the way each other. they do today. The continents were 250 million years ago grouped together in a “supercontinent” Life begins called Pangaea. At first, nothing lived on Marrella, a life form from Earth. The earliest life 540 million years ago. forms appeared 4,600 million years ago. Over time, more species developed. Now there 120 million years ago are millions of different types of life, and over Pangaea split in two, forming Laurasia in the north and 7.5 billion people. Gondwana in the south. 50

Under ice For much of the last two million years, huge ice sheets covered large parts of Northern Europe and North America. We are currently living in a warmer period. Changing surface The Andes mountains formed 45 million years ago. The Earth’s surface changes constantly. As continents crash Mammoths lived during together or move apart, mountain the last ice age. ranges are forced up, then worn down. Rainforests become icy wastelands, oceans expand and shrink, and glaciers turn into deserts. The Atlantic Ocean If the sea level today was opening, pushing was as high as it was North America and 500 million years ago, Europe apart. London, New York, and Sydney would all be Africa was moving northward, on its way to underwater. crashing into Europe. Climate change Humans have a direct impact on Earth’s climate. We burn fossil fuels such as coal, oil, and gas to make power. This releases dangerous gases into the air, making Earth hotter. 80 million years ago Burning fossil fuels 51

Cars SEE ALSO ▸▸ Electricity p.87 Cars are vehicles that travel on roads. The shape and size of a car depends on its use, such as for a family or ▸▸ Engines p.92 for racing. Cars are powered by engines. Engines can be powered by fuel such as gasoline or diesel, or by ▸▸ Fossil fuels p.110 using electricity. ▸▸ Inventions Parts of a car pp.136—137 All cars have a strong metal frame ▸▸ Sports p.239 called a chassis. Attached to this are all the other parts, such as the ▸▸ Transportation engine and wheels. pp.258–259 The engine is powered by burning gasoline or diesel. This shaft takes The axle spins to power from the move the wheels engine to the axle. forward or backward. The battery The front wheels are Electric car provides electricity turned by the driver’s to start the car and steering wheel. Today, many cars are powered by electricity. to power the lights. Fuel-powered cars release harmful gases into the air, but electric cars don’t. The battery in an Formula 1 electric car is powered up at a charging point. Some of the world’s fastest cars take part in a racing competition called Formula 1. They compete on special tracks and around some city streets. The cars have long, low shapes to help them go super fast. 1998 Ferrari F300 F1 52

Castles SEE ALSO ▸▸ Buildings p.48 Most castles were built between 1000 and 1500 ce. They ▸▸ Engineering p.91 had homes and workshops inside their walls. Kings and ▸▸ Europe p.94 wealthy people built castles as protection from enemy ▸▸ Imperial Japan attack. Once cannons were invented, they were no longer safe. Many fell apart over time, but some are still standing. p.131 ▸▸ Knights p.142 Stone castles The bailey was The largest tower ▸▸ Homes an open space inside in the castle was Later castles in Europe had stone walls the castle with areas called the keep. pp.244–245 and towers. The biggest ones could hold for growing food. hundreds of soldiers. Smaller stone Stone walls castles were home to just were difficult for a single family and attackers to climb. its servants. Sheep and other livestock were kept safe in the castle. The drawbridge People kept watch Some castles had could be lifted to for the enemy from a water-filled moat keep the enemy tall towers. around them for out of the castle. extra protection. Early castles Himeji Castle in south Japan is called “the white heron” as its Hundreds of “motte and bailey” castles peaks look like wings flapping. were built from 1020–1200. They had two parts—a mound of earth Japanese fortress (motte) topped by a tower, and a courtyard (bailey). Castles in Japan were designed with towers built Many castles of both wood and stone. were built on The central tower was used hilltops so they as the main hideout if the had a clear view castle was attacked. of everything around them. 53

Cats SEE ALSO ▸▸ Dogs p.81 The cat family are all meat-eaters. They have sharp teeth that let them slice up their food. Cats are very ▸▸ Food chains fast, with strong bodies that let them run, jump, p.107 and even swim. ▸▸ Habitats p.126 Cats have good hearing. ▸▸ Pets pp.152—153 ▸▸ Sight p.226 ▸▸ Vertebrates p.266 Small wild cats Whiskers help cats sense their Most wild cats are much smaller surroundings. than lions. The colors of their fur help them to be camouflaged, or hidden, in their habitat. Cat Pet cats Chartreux tongues Cats were one of the first animals that are covered in humans tamed from the wild to become sharp hairs. They pets, around 12,000 years ago. are used to clean meat off a bone and to Big cats wash their The largest types of cat fur. are known as “big cats.” They include lions, tigers, leopards, and jaguars. These are the only cats that are able to roar. Male lions have longer hair over their shoulders, called manes. Lynx Night vision Lion 54 Leopard Cats hunt at dawn and dusk. Their eyes are good at seeing when there is not much light. Their eyesight is six times better than a human’s.

Caves SEE ALSO ▸▸ Animal homes Caves are large natural holes in the ground. They are usually formed when rock is hollowed out by running p.23 water over millions of years. Prehistoric humans used caves for shelter, and some people still live in caves today. ▸▸ Erosion p.93 They are also home to lots of animals, including bats. ▸▸ Glaciers p.122 ▸▸ Rocks and minerals p.214 ▸▸ Homes pp.244–245 Cave network A stream pours into A level area of the cave through an rock without soil Caves form when rainwater dissolves opening in the ground covering is called the soft limestone rock in the ground. known as a sinkhole. a pavement. They often contain fantastic rock features, such as stalactites and stalagmites. Columns form where Stalactites grow stalactites and down from the stalagmites join up. roofs of caves. Stalagmites build upward from cave floors. An underground river wears away more rock, creating chambers and tunnels. Ice caves Biggest cave Glaciers are rivers of ice The 40-story-high that move very slowly. Hang Son Doong cave Some glaciers have in Vietnam is the caves inside them. They world's biggest cave. are made by streams of Inside, it has a river, water tunneling through a forest, and even its the glacier. own clouds! This ice cave is inside 55 A river flows through a glacier in Iceland. part of the huge cave.

Cells SEE ALSO ▸▸ Body cells p.41 Living things are made from tiny parts that stick ▸▸ Genes p.119 together, called cells. Cells come in different shapes ▸▸ Heart p.128 and sizes depending on the job they do. They can ▸▸ Photosynthesis divide and make copies of themselves. p.191 ▸▸ Plants p.194 ▸▸ Sickness p.225 Plant cell Cell wall Cytoplasm Bacteria The strong outer This is the liquid inside Plant cells can collect air and make wall gives the the cell that everything Bacteria are living things their own food from sunlight. They cell and plant else floats in. Chemicals made from just one cell. have a strong cell wall, which gives their shape. mix together here. They can divide to make the plant strong stems copies of themselves. This and leaves. Cell membrane is how germs spread and The cell membrane is make us sick. a barrier that keeps the cytoplasm inside the cell. Nucleus The nucleus controls the cell and contains instructions called genes. Animal cell Animal cells use oxygen to break down sugar and make energy. Animals get sugar from the food they eat, while oxygen gets to the cells through the blood. Cell membrane Cytoplasm Nucleus Mitochondrion Chloroplast Vacuole Mitochondrion This is where energy Chloroplasts collect The vacuole is a storage from sugar is released sunlight and use air and bubble filled with liquid to power the different water to make food. food, water, or waste. parts of the cell. 56

Changing states SEE ALSO ▸▸ Atoms p.34 Most materials can change between being solid, liquid, ▸▸ Gases p.117 or gas, depending on their temperature and how tightly ▸▸ Water p.120–121 packed they are. Substances such as water can change ▸▸ Liquids p.148 from one state to another and then back again. ▸▸ Solids p.234 ▸▸ Temperature p.252 Different states Liquid Materials flow when All substances are made from tiny they are liquid. The particles that are arranged in different particles are close but ways depending on whether they move past each other. are solid, liquid, or gas. Water vapor is Solid Ice is water water as a gas. Solid materials keep as a solid. their shape. The particles are very close together. Gas Materials move in all directions when they are gas. The particles are far apart. Drinking water is water as a liquid. Shifting states Melting When we heat Solidifying When a liquid Evaporating When a Condensing When water a solid, it melts and like this lava cools, liquid changes into a gas, turns from a gas back The same material can changes to a liquid. it becomes solid. it evaporates as steam. into a liquid form, this change from being solid is condensing. to liquid and from liquid to gas when it is heated, and back again as it cools. These changes are called melting, solidifying, evaporating, and condensing. 57

Chemistry SEE ALSO ▸▸ Atoms p.34 ▸▸ Body cells p.41 Chemistry is a science that looks at the smallest ingredients ▸▸ Elements p.90 of everything, called elements. It studies how elements ▸▸ Engineering p.91 react when we mix them together, and how tiny particles ▸▸ Changing states in materials are arranged and can be rearranged. p.57 ▸▸ Materials p.157 Building blocks Particles called electrons move around the outside. Everything around us is made 1. Atoms from tiny parts called atoms. Atoms are so small we can’t see them Atoms join to each other and and they’re mostly empty space. other types of atoms to They have even smaller particles make arrangements called inside. The type of atom depends molecules. These basic on the number of particles inside it. building blocks are what chemistry investigates. An atom is mostly Gold empty space. If an atom The center is 2. Elements Antimony was the size of a called the nucleus. Materials that that have Plutonium football stadium, It contains particles only one type of atom called protons are known as elements. the nucleus would be and neutrons. Elements have just one the size of a marble. ingredient—themselves. Antimony, plutonium, Chemical reaction and gold are all elements. When two or more elements come together to make a new compound, it is called a chemical reaction. Reactions can fizz, burn, or even explode when new compounds are made. Iron and oxygen react 3. Compounds to form rust. Elements that have joined together are called compounds. For example, water is a compound made from the elements oxygen and hydrogen. Oxygen and hydrogen combined make the compound water. 58

Circuits SEE ALSO ▸▸ Computers p.71 A circuit is when an object that uses electricity is ▸▸ Electricity p.87 connected with wires to a power source. Circuits in our ▸▸ Light p.147 homes connect lights and appliances, like the fridge or ▸▸ Measuring television, to electricity. p. 159 ▸▸ Television p.251 How circuits work Wires are covered in When a circuit is a complete plastic to stop loop with no gaps, electricity can electricity flow around it. We use symbols escaping. to represent the different parts of the circuit. Battery “cell” Batteries are power Electricity sources that hold travels through electricity. Electricity metal wires. can flow around the circuit when we Switch connect it to both Electricity only flows ends of a battery. around the circuit when the switch closes and is Light bulbs switched on. Once the Electricity makes the switch is opened, light bulb switch on the circuit breaks. and light up. Objects in a circuit that need electricity to work are called components. Crocodile clips The flow of Circuit boards connect circuit wires to objects. electricity Computers have tiny boards in them called around the circuit circuit boards. Circuit is called the boards have lots of wires connected up current. to tiny components to make the computer work. 59

Climate change SEE ALSO ▸▸ Arctic p.25 Climate is the average weather for an area. The way we ▸▸ Carbon cycle p.49 live is changing the Earth’s climate. It is becoming warmer. ▸▸ Fossil fuels p.110 This change is causing extreme weather conditions, such ▸▸ Industrial as long periods of little rainfall, called droughts, and huge storms. Many countries are now trying to stop Revolution p.133 climate change. ▸▸ Pollution p.198 ▸▸ Storms p.246 More than What is the cause? 39 billion tons Power stations, factories, and cars pump gigantic amounts of the gas (35 billion metric tons) carbon dioxide (CO2) into the atmosphere. This gas acts like of CO2 is released a blanket, trapping the sun’s every year. heat and warming our planet. Exhaust fumes from road traffic are one of the biggest causes of climate change. How is the climate changing? What can we do? Solar panels make energy from sunlight Climate change is making our summers hotter. Floods, We need to reduce the amount and do not release droughts, and powerful storms are becoming more of fuels we burn that release CO2. harmful gases. common. The ice in cold parts of the world is melting, We can do this by using sources which is making sea levels rise. of energy that do not produce CO2, such as sunlight, wind, and water. Flooding in New Orleans, Louisiana 60

Clocks SEE ALSO ▸▸ Machines p.150 A clock is a device used to keep track of time. Ancient ▸▸ Measuring p.159 civilizations measured time by falling sand, flowing water, ▸▸ Numbers p.185 or the position of the sun. Modern clocks are either digital ▸▸ The sciences or have clockwork mechanisms. pp.218–219 12 ▸▸ Sun p.247 ▸▸ Time zones p.255 How does a 2 Clock face clock work? 3 This part of the clock shows the time, in hours, Clocks make regular 4 minutes, and seconds. movements for measuring time. They do this using Minute hand machinery known as The long minute hand clockwork. The clock makes a full turn around face has moving hands the clock every hour. that show the hours, minutes, and seconds. Hour hand The short hour hand makes Gears a complete turn around the Gears are wheels that lock clock every 12 hours. together. In a clock, they make the hands turn at Second hand different speeds. This long, thin hand makes a complete rotation of the clock every minute. Pendulum 5 Then and now Each swing of the pendulum 7 turns the gears one click, In the past, people had usually once a second. 6 sundials, which showed the time of day using shadows cast by the sun. Modern digital clocks show time as numbers. The first Counterweight Sundial This weight stores energy Digital clock pendulum clock so the clock can work without a battery. was made by Dutch scientist Christiaan 61 Huygens in 1656.

The story of... Clothing Over time, the things we wear have changed a lot. The clothes that people wear often reflect where they live, what jobs they do, and how much money they have. Clothes are generally made from woven materials such as cotton, wool, or silk, with special designs. They are often worn for show, but can also be practical or even worn for fun. First clothes This long, embroidered The first people wore dress is made clothes made of animal skins of silk. to keep out the cold and wet. They later discovered how to clip the wool off a sheep’s back and spin it into a thread that could be woven to make material. The Roman A toga wraps Emperor Nero around the wore a purple toga body and is thrown over and punished anyone the left else who wore purple shoulder. with death. Roman clothes Court finery The main item of clothing for In the royal courts of Europe in the ancient Romans was a simple 1500s and 1600s, men and women tunic. For special occasions, men wore special, expensive clothing. wore a long piece of cloth called The women wore long, embroidered a toga on top of their tunic. dresses, while the men wore padded Women wore a woollen jackets with short trousers shawl called a palla. and silk stockings. 62

A sari Traditional costume 27 ftcan be up to Around the world, people wear (8 m) long. clothes that are unique to their country. For traditional events, A long cotton or silk Indian women wear saris, while sari is wrapped around the waist. Japanese women wear long, decorated kimonos with wide sleeves. A kimono is tied at the back with an obi, or sash. Kimono A padded Hats were jacket, designed to called a match the rest doublet. of the outfit. Weaving The cotton, silk, wool, or linen material used to make clothes is woven on a loom. Different colored threads can be used to make patterns, such as checks or stripes. A New Look Loom skirt was full and long, with a small waist. A suit is often Traditionally, the worn with a shirt and tie. bottom button of a suit jacket should be left undone. The New Look Smart suit During World War II (1939–45), material All around the world, for new clothes was in short supply. businessmen and women wear a In reaction to this, fashion designer suit of a jacket and matching pants. Christian Dior introduced in Paris in The suit was developed in Europe 1947 a “New Look” for women. during the 1800s and is a practical The full skirts were shorter and became fashionable uniform for work and other around the world. formal occasions. 63

Clouds SEE ALSO ▸▸ Gases p.117 Clouds are made of tiny droplets of water or ice. They ▸▸ Water form when air that contains water rises and cools. As well as making rain, snow, and hail, clouds help control pp.120–121 our planet’s temperature. ▸▸ Storms p.246 ▸▸ Temperature Types of cloud High-level clouds p.252 There are many different types Cirrus ▸▸ Water cycle p.270 of cloud. Some float very These wispy ▸▸ Weather p. 271 high up, while others hug clouds form very the ground. Clouds may high up in the air. Cirrocumulus look white and fluffy Cirrostratus clouds or dark and stormy. sometimes break up to form these little clouds. Altostratus Medium-level clouds These clouds form a thin sheet across the sky. Altocumulus Cirrostratus These clouds are These thin clouds broken into segments, are made of tiny or “cloudlets.” ice crystals. Stratus Low-level clouds Stratocumulus These flat sheets These big clouds form a of cloud can be lumpy layer in the sky. white or gray. Cumulonimbus Nimbostratus Towering and huge, Tall and gray, these clouds cumulonimbus clouds bring hours of rain or snow. are often seen during thunderstorms. Cumulus These fluffy heaps of cloud are often seen on sunny, breezy days. Temperature Clouds Cloud or UFO? control reflect heat from Clouds that do not move Clouds reflect the the sun. can form in the sheltered sun’s heat, stopping air behind areas of high the Earth from getting Clouds ground, such as mountains. too hot. They also trap trap heat They are shaped like saucers heat below them, so a reflected or lenses and have been cloudy night is warmer from the mistaken for unidentified than a clear one. Earth. flying objects (UFOs)! 64

Coding SEE ALSO ▸▸ Codes p.66–67 Computers follow instructions from special programs. These instructions are known as code, and writing ▸▸ Communication them is called coding. Code can be written in many p.69 different coding languages. ▸▸ Computers p.71 Computer languages ▸▸ Internet p.138 Programming languages tell computers what to do. This ▸▸ Language p.144 example shows a text-based language called Python. ▸▸ School pp.272–273 Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 26 2016, Hello World! 10:47:25) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on Darwin Type “copyright”, “credits” or “license()” for more information. >>> print ( ‘Hello World!’) The first programmer was Input Output Instructions are typed into a text When the program is run, it follows the Lady Ada window. These instructions tell the typed instructions. Here, the computer Lovelace computer to show, “Hello World!” screen shows, “Hello World!” (1815–1852). Learning to code Input Some computer In Scratch, languages are easier coding is done by to learn than others. putting together Scratch uses colorful instruction blocks. blocks of code that you can arrange to make your own games. Output The blocks control the actions of the characters here, on the “Stage.” 65

The story of... Morse Code Codes Morse Code represents letters and numbers as Codes are words, letters, and numbers that are dots and dashes. It was used used to represent other words, letters, and to send messages through numbers. People used codes to communicate wires before telephones with each other, or to keep things secret. Others, such as DNA, are just instructions. were invented. The ancient Morse Code tapping machine Egyptians used hieroglyphics as a writing system to record their history. Writing with pictures Bonjour Nee-how, Mandarin The ancient Egyptians used Boh-zhoo, French drawings to communicate, instead of written words. These symbols are called Konnichiwa, Japanese Languages Hello hieroglyphics. Hieroglyphics were not understood by modern people until Merhaba The different languages English humans speak are types a stone was discovered with a Mehr-hah-bah, of code. Until you learn a Zdrast-wui-tyeh, translation of hieroglyphics into Turkish foreign language, hearing Russian someone using it to speak Greek, allowing the “code” to or reading their writing will be worked out. make little sense to you. Programming Holá Jambo Oh-lah, Computers need Spanish Ja-m-boh, Swahili instructions to operate. These are created by programmers, who use combinations of symbols and words. Programming is often called coding. Nômoshkar, Bengali 66

Codes in war This system of writing from ancient Greece is One of the most common still not understood. uses for codes is to keep secrets, especially during wartime. When Linear A tablet commanders give orders to their armies, they need those orders to be kept secret from the enemy. Code breakers try to crack the codes and learn enemy secrets. The Enigma Code Unbroken codes was broken by a Some languages remain a machine called a mystery—their writings have been discovered but never “bombe,” created by Alan Turing. translated. It is likely that we will never know Messages what they mean. typed here were encoded DNA strand by special wheels. DNA DNA—short for Deoxyribonucleic acid—is found inside the cells of all living things, including plants and animals. It contains a genetic code on how the living thing will form. The Enigma machine was used by Germany during World War II. 67

Comets SEE ALSO ▸▸ Asteroids p.30 Comets are objects in the solar system made of ice, ▸▸ Gases p.117 dust, and rock. They have a hard core and long tails of ▸▸ Gravity p.125 gas and dust. Every now and again they appear within ▸▸ Meteorites p.164 sight of Earth, before disappearing into deep space. ▸▸ Solar system p.233 ▸▸ Sun p.247 Dust tail Gas tail Two tails The tails Circling the sun start to When a comet gets close to the get shorter. Comets move around the sun. sun, its ice melts and two tails Their tails always point away form: one made of gas and one 68 from the sun, but in slightly made of dust. different directions. The tails Halley’s Comet get longer as the comet gets closer to the sun. Halley’s Comet makes one full circle around the The tails start sun every 75 years, and to get longer. it has been recorded by historians for more than 2,000 years. The Bayeux Tapestry, which tells the story of the Battle of Hastings, shows it moving across the sky in the year 1066.

Communication SEE ALSO ▸▸ Codes pp.66–67 The different ways people keep in touch are all ▸▸ Computers p.71 forms of communication. People have many ways ▸▸ Internet p.138 of communicating, such as talking to each other or ▸▸ Satellites p.215 writing letters. Most modern communication other ▸▸ Games than talking is done using mobile phones. pp.240–241 Mobile phones ▸▸ Telephones Mobile phones are very useful, p.250 as they let people communicate in many different ways. Video calling This type of call lets Email you see the person Email lets us send you are speaking to. written messages. It is much faster Gaming than sending a letter People can chat through the mail. and talk to one another while Photo Telegraph they play games. messaging In the early 1800s, messages Photos can be taken were sent in a series of dots Internet and then shared and dashes (called Morse The internet with other people. Code) over a thin wire. lets people find out information Phone 69 very quickly. Using a phone lets you talk to others Texting around the world. Texts are short written messages. Past and future Texting is a popular way to communicate. People have always found clever ways to HoloLens communicate. The first This is a computer you humans drew pictures for can wear. It displays 3-D each other on cave walls. objects that the wearer Modern communication is can interact with. becoming more high tech.

Compass SEE ALSO ▸▸ Ancient China A compass is a simple instrument that helps people find their way around by showing directions. It is usually p.16 round and contains a freely rotating, magnetic needle that always points north–south. This lets you work ▸▸ Inside Earth out other directions. p.135 ▸▸ Magnets p.151 ▸▸ Maps p.155 ▸▸ Navigation p.182 How to use a compass Directions The main directions are When using a compass, lay it flat and north (N), east (E), south (S), then turn it until the north end of the and west (W). They are called needle is above north on its base. Now the cardinal directions. you know which direction is north, you can find the other directions. Finer directions Between the four cardinal Direction hand directions are more precise This hand can be turned to ones, such as northeast (NE) mark the direction that you and southwest (SW). want to travel toward. Needle Compass rose The magnetic needle The base of the compass detects Earth’s magnetic shows all the different field and lines up with directions and is known north–south. The end of the as the compass rose. needle pointing to north is usually colored or marked. A compass on a phone shows which direction the phone is pointing in. Directions can 21st-century be written as compass angles. For example, southwest is 225º. Many of today’s phones contain a device called a Walking compass magnetometer. It detects the Earth’s magnetic field A walking compass has and lets you use your a see-through back so phone as a compass. that it can be used on top of a map. This lets you work out where you are and which direction you want to go in. 70

Computers SEE ALSO ▸▸ Coding p.65 Computers are machines that store information and can be ▸▸ Codes pp.66—67 programmed to perform tasks. Many show information on ▸▸ Communication a screen, such as on a mobile phone or a laptop. Others are hidden inside objects to make them work. p.69 ▸▸ Internet p.138 Screen ▸▸ Machines p.150 Words and images are ▸▸ Robots p.212 displayed on the screen. USB port How computers work Work can be saved and moved between devices on Computers are programmed a tiny hard drive, called a in code to perform different USB. It is plugged in here. tasks. This is called software. The programs are stored and run by the parts, or hardware, of the computer. Battery Keyboard Computers need Words typed on electricity to work. The the keyboard battery provides and appear on stores the electricity. the screen. Processor Motherboard RAM Hard drive This part performs the This connects everything, so This part stores information, This stores information calculations that make that different parts of the but only while the computer even when the computer the computer work. computer can communicate. is switched on. is switched off. How we use Traffic lights Video games Industrial robot computers Computers control Game consoles are computers when the lights that let you play games on a Computers tell big Computers are found change color. television screen. machines what to do— inside many everyday often the same thing objects. Computers let us 71 over and over again. program these machines to perform specific tasks.

Conservation SEE ALSO ▸▸ Climate change Conservation is the protection of habitats and the plants and animals that live in them. This is important p.60 because human activity, such as cutting down trees ▸▸ Farming p.98 and throwing away garbage, destroys animal homes. ▸▸ Forests p.109 ▸▸ Habitats p.126 Habitats Forests ▸▸ Pollution p.198 Animals live in People cut down trees ▸▸ Zoo p.281 areas we call habitats. for wood and to make space When people damage for farms. Some wood is In danger habitats, they threaten Many animals are many animals and plants. used to make paper. in danger of dying out. Wildlife reserves protect Recycling paper helps When a type of animal has habitats and the animals completely died out, we say that live in them. save trees. it is extinct. National parks and laws try to stop animals from becoming extinct. Under threat Here are some of the ways humans have affected animals and their habitats, or homes. We can help protect animals by making small changes in our everyday lives. Pollution Fishing Pollution happens People have caught so when people release many fish from the sea dirty or harmful that many species are substances into the world becoming rare. We can now around them. It can kill choose to eat farmed fish wildlife. Reusing and instead, leaving wild recycling things reduces fish alone. the amount we throw away. 72

Constellations SEE ALSO ▸▸ Ancient Greece Ancient civilizations looked at the night sky and grouped stars into patterns or constellations to p.18 represent heroes, creatures, and objects. As the Earth moves, the constellations appear to move across the sky. ▸▸ Galaxies p.116 The stars are all at different distances from the Earth. ▸▸ Myths and legends p.178 ▸▸ Navigation p.182 ▸▸ Seasons p.221 ▸▸ Stars p.242 Modern constellations This star is called Menkent, meaning Astronomers today look at 88 “shoulder of constellations. Some can be seen from the Centaur.” both the north and south parts of the world, others from only one or the other. This star is called Mizar. Ursa Major Betelgeuse is a red Centaurus Also known as the Big Dipper, supergiant star. This constellation Ursa Major (“great bear”) can represents a half-man, only be seen from the northern half-horse creature half of Earth. from Greek myth. It is only visible from the southern half of Earth. Navigation Ancient sailors used the constellations to find where they were. By looking at the pattern of stars they could work out where they were on Earth. One key signpost was Polaris, the North Star. Orion’s Over thousands of belt years, stars shift and constellations change their shape. Orion The hunter, Orion, is one of the most well-known constellations. Three bright stars line up to make Orion’s belt. 73

Coral reefs SEE ALSO ▸▸ Animal homes Coral reefs are underwater structures where many plants and animals live. They are made by tiny animals called p.23 corals that grow hard shells. When they die, the shells remain and new corals grow on top of them. Some coral ▸▸ Fish p.101 reefs can grow very big. ▸▸ Invertebrates p.139 ▸▸ Oceans and seas p.187 ▸▸ Vertebrates p.266 Coral reef Trigger fish eat coral, Green sea turtles Great Barrier Reef using strong teeth that have sharp beaks This reef is home to more than 1,500 Coral reefs cover only a tiny crush the corals’ shells. to break off different types of fish. It is the part of the ocean, but are seagrasses to eat. longest reef in the world and is home to nearly a quarter of found off the east coast of Australia. all ocean life. The reefs are full of food for sea creatures. Tiny clown fish This red coral forms These hawkfish hide live among the a branchlike shell. among the coral, tentacles of swimming out to grab anemones. The organ pipe small fish and shrimp. coral has feathery tentacles that The shells of these trap food. corals are covered in small black spines. Anemones have swaying tentacles Banded coral shrimp that sting fish if they are small animals that get too close. feed by cleaning the skin of fish. Blue corals join If threatened by other Fan corals bend and Many small animals together to form animals, reef crabs sway in the water, use the seagrasses columnlike groups. pretend to be dead. catching food. as hiding places. 74

Crafts SEE ALSO ▸▸ Ancient Rome A craft is something done by hand, often with a lot of skill. People have always used natural and artificial materials, p.20 such as clay or glass, to make things. Craft objects can ▸▸ Art p.28 be for everyday use, such as plates for eating, or for ▸▸ Books p.44 decoration, such as jewelry. ▸▸ Clothing Pottery pp.62–63 ▸▸ Inventions Potters use clay from the ground to make things such as plates, bowls, pp.136–137 cups, and vases. They shape the clay, then put it in a special oven called a kiln Glass to heat it up and make it hard. Roman jug African wooden figure Woodcarving Glasswork Woodworkers shape When sand is heated wood into different to a very high things. They can make temperature, it furniture, bowls, and other becomes liquid glass. useful or decorative items. This can be shaped and cooled into solid Native American woven rug objects such as jugs. Red terra- Ancient Egyptian vase Beads are made cotta in different sizes clay and shapes. Weaving Beading Weavers bring together wool, Materials such as glass -Eastern beads can be made into beads. silk, or cotton threads to make Beads can be threaded material. This can be used for onto string to make jewelry, or sewn many things, such as clothes, onto clothing. rugs, and wall decorations. Ancient Middle 75

Dance SEE ALSO ▸▸ Clothing pp.62–63 Moving your body in time to a beat is called dancing. ▸▸ Music People dance to music to enjoy themselves, to be close to their friends, and to show their skills. Dances can be pp.176–177 very formal with set movements to follow, or much ▸▸ Festivals more casual and relaxed. pp.206–207 Fans used ▸▸ Religion p.208 in dance ▸▸ Sports p.239 ▸▸ Theater p. 253 Arms above the head Elegant arm positions Traditional dance Feet lift high Religious dance Many countries or regions have off the ground Some people in the Islamic religion their own dances, called traditional dance by spinning around in dances. Korean fan dancing Tribal dance circles. This is called Sufi whirling involves making shapes with fans. Many African tribal dances follow and helps them feel closer to God. drum beats and have strong rhythms. The historical dances of tribes can include whole crowds. Acrobatic moves Bollywood dance Bollywood films from India are famous for their dance routines. Often, the whole cast perform exciting dances with precise arm movements and footwork. Precise Ballet hand Ballet is a formal shapes dance style with graceful and Complicated strong moves. footwork Ballet dancers use a series of Street dance Latin dance precise steps, Street dance often involves Latin dance began in Latin leaps, and lifts. dancers making up their America. Dances such as the own moves to hip-hop tango involve two people Pointed toes music. They usually do dancing close together, as flips and spins. if they are in love. 76

Day and night SEE ALSO ▸▸ Earth p.83 Day and night are times of light and darkness that ▸▸ Light p.147 occur because the Earth spins, or rotates. One full ▸▸ Moon p.171 day-and-night cycle is called a “day” for short. The half ▸▸ Seasons p.221 of the spinning Earth that faces the sun has daylight, ▸▸ Solar system p.233 and the half facing away from the sun is in darkness. ▸▸ Sun p.247 ▸▸ Tides p.254 What makes Earth spins on day and night? its axis, which is The sun is where an imaginary line Earth’s light and As the Earth spins round, that goes through heat come from. parts of it move in and out the North and of the sun’s light. The South poles. light parts are in day and the dark parts are in night. It takes the Earth 24 hours to make one rotation. Half of the Earth Light from The Earth is in darkness. the sun used to spin Half of the much faster in the Earth is in light. distant past, and the days were much shorter. Moving sun Eclipses The sun appears to move across the sky during the day The moon circles the as the Earth spins around it. It rises in the east and sets Earth. Occasionally, it in the west. In the summer, the sun is higher in the sky blocks our view of the than in the winter. sun during the day, and the sky darkens for a few minutes. This event is called a solar eclipse. If the moon blocks all of the sun, it is called a total eclipse, and stars can be seen in the sky. Total eclipse 77

Deserts SEE ALSO ▸▸ Africa p.12 The world’s driest areas are deserts. They have less than ▸▸ Antarctica p.24 10 in (25 cm) of rain a year. Deserts can be sandy, rocky, or ▸▸ Habitats p.126 even icy. Most deserts have hot days and cold nights. Some ▸▸ Mountains p.172 animals survive here by getting water from plants or by ▸▸ Plants p.194 only moving around after sunset. ▸▸ Reptiles p.210 ▸▸ Weather p.271 Desert living Golden eagles have Egyptian vultures use good eyesight to the hot air that rises Animals and plants living in deserts look for food from from the desert to must be able to survive with little a long way up. soar high in the sky. water. In hot deserts, animals are active at night. During the day, they Sand dunes are hills of Camels store fat retreat under the sand to stay out sand that are created in their hump. of the hot sun. by strong winds. They They can go for move in the wind. days without Acacia trees have water or food. long roots to reach Cheetahs get water deep underground from the blood of to find water. their prey. Most of the desert is made of rocks and gravel, not sand. Horned vipers Deathstalker hide under the scorpions have sand. deadly poison in their tails. Agama lizards warm Peyote cactuses up in the sun, then Sahara frogs store water in hide under rocks to stay near any their thick stems. keep cool. pools of water. Jerboas get all Scarab beetles the water they eat animal waste. need from the seeds they eat. Sahara Desert The Sahara Desert is in the north of Sahara ants have long Africa. It is the world’s largest hot legs to keep their desert. The Sahara is spread across bodies off the hot sand. many different areas, including mountain ranges and sand dunes. 78

Digestion SEE ALSO ▸▸ Food p.106 Digestion is when we eat food and it gets broken down and used by our bodies to give us the energy we need to ▸▸ Eating move and stay healthy. Your digestive system starts with pp.104—105 your mouth and ends at your bottom. ▸▸ Human body Esophagus p.130 ▸▸ Lungs p.149 ▸▸ Taste p.249 Food journey Stomach Inside the stomach, Once it has been swallowed, food liquid chemicals are passes into the stomach. From here, added to the food it moves through the intestines and and churned around. is then pushed out of the body. Small intestine A large meal takes After passing through the stomach, one to three days the mushed-up food liquid travels through to pass through the the small intestine. digestive system. Digestive system In the mouth When we chew, food is broken and mixed with saliva. Different teeth do different jobs. When the chewed food is swallowed, it goes down a tube called the esophagus. Esophagus Sharp incisors cut food. Large intestine Pointed Flat molars The waste parts of canines crush food. food stay in the large tear food. intestine until they are pushed out as poo. 79

Dinosaurs SEE ALSO ▸▸ Asteroids p.30 Dinosaurs are reptiles that lived on Earth for 160 million ▸▸ Birds p.39 years, about 225 million years ago. Some were fierce ▸▸ Fossils p.111 meat eaters, others gentle plant eaters. Scientists have ▸▸ Prehistoric life learned about dinosaurs from studying the fossils left behind when the dinosaurs died. p.202 ▸▸ Reptiles p.210 Ceratopsians Triceratops’s ▸▸ Rocks and minerals frill was used to Ceratopsians were plant-eating protect the neck p.214 dinosaurs. They had a protective during fights. frill around their head. The horns were used for Dinosaur fossils defending itself against other The remains of dinosaurs dinosaurs. have been preserved in rock. Some even show the Dinosaur remains dinosaur’s last meal have been found on still inside them. every continent, including Antarctica. The sharp beak was used for tearing pieces off tough plants. Archaeopteryx fossil The legs had A long neck let to be strong, Brachiosaurus as Triceratops reach leaves weighed the at the top of same as four cars. tall trees. Triceratops (try-SER-uh-tops) Tyrannosaurus rex Sauropods (TIE-ran-oh-SORE-us rex) Sauropods were Sharp teeth let T. rex enormous plant- tear meat off bones. eating dinosaurs. They had to eat all Theropods The long tail the time to fuel their was used for huge bodies. Theropods were fierce meat- balance. eating dinosaurs. They lived in Brachiosaurus what is now North America. (brack-ee-oh-SORE-us) 80

Dogs SEE ALSO ▸▸ Animal families Dogs are meat-eaters with sharp teeth and excellent senses. They include wild jackals, foxes, and wolves, as p.21 well as the tame dogs we keep as pets in our homes. Wild ▸▸ Cats p.54 dogs hunt for food or eat animals that have already died. ▸▸ Deserts p.78 ▸▸ Hearing p.127 Pet dogs ▸▸ Pets pp.152—153 ▸▸ Work p.274 There are lots of different types of dogs. Some are friendly and make good pets. Some are strong and loyal to their owners and are good at guarding things. There are Beagle Lhasa Apso 300more than different types of pet dog. Irish Wolfhound Grey Fennec fox Working dogs wolf Foxes For thousands of years, Wolves dogs have been known These pointy-eared animals can as man’s best friend. The grey wolf is the most be found in deserts, icy locations, This is because they closely related animal to mountains, and even cities. The work closely with pet dogs. Wolves live and fennec fox is the smallest fox. people. Dogs work in hunt in groups called packs. the fields, hunt, and even sniff out people who have been buried in rubble or snow. 81

Early humans SEE ALSO ▸▸ Africa p.12 The first humans were similar to apes, such as gorillas and chimpanzees. Over millions of years, they learned to walk ▸▸ Evolution p.95 on two legs and got smarter as their brains grew larger. They also lost most of their body hair, slowly becoming ▸▸ Fossils p.111 more like the humans we are today. ▸▸ Monkeys and apes p.170 ▸▸ Exploration pp.180–181 ▸▸ Stone Age p.243 Ancient humans 7 million Hominins 4 million years ago Early humanlike years ago There were many different species, called hominins, types, or species, of human developed from apes. relatives. Some of them lived They spent a lot of their at the same time and may have time in trees, and began met each other regularly. walking on two legs. First toolmakers Basic rock Prehumans Homo habilis was one Australopithecus 2 million of the first species to tool 3 to 2.5 is a species of years ago use stone tools to million hominin that help with work. The years ago learned to walk tools made it easier fully upright, like for them to get food. humans do today. First fire-makers 200,000 Modern humans Human relatives became years ago Modern humans appeared in steadily more clever and Africa. The tools they made ate more meat. Homo Hand axe helped them adapt to other erectus may have been environments. They spread using fire to cook food across the world, while other over a million years ago. humanlike species died out. Human evolution How do we know? The first humanlike animals were short, had Ancient humans left behind small brains, and lived mostly in trees. Over bones and tools. Scientists many years, they began spending more study the bones to learn of their lives on the ground. everything from how ancient humans walked to what they ate and what diseases they Ancient skull had. Their tools can reveal information about daily life. 82

Earth SEE ALSO ▸▸ Atmosphere p.33 Earth is the planet we live on. It is the third planet away ▸▸ Earth’s surface from the sun and the largest rocky planet in the solar system. Earth is about 4.5 billion years old. At the moment p.84 it is the only planet known to support life. ▸▸ Gases p.117 ▸▸ Water pp.120–121 Earth has seven ▸▸ Solar system large land masses called continents. p.233 ▸▸ Sun p.247 Our home After seeing the Earth has all the right first pictures from conditions for life. It is just space, scientists nicknamed Earth “the blue marble.” the right distance from the sun, it has oceans of liquid water, and a blanket of gases called an atmosphere that protects it from outer space. Earth’s atmosphere is mostly made of two gases, nitrogen and oxygen. About 70 percent of the Earth’s surface is covered in liquid water. Habitable The white swirls are clouds. Thick patches of white are storms. Too cold Too hot Earthrise Safe zone Earth is here On Earth, we see a 83 sunrise and a moonrise Earth orbits the sun in what is known as the as the sun and moon habitable zone (in green), where liquid water become visible in the sky. can exist. Closer to the sun, it is too hot, and When astronauts orbited farther away it is too cold. the moon in 1968, they saw our own planet rising in the sky.

Earth’s surface SEE ALSO ▸▸ Earthquakes p.85 The outer layer of the Earth is called the crust. It is made up of many pieces, called tectonic plates, which fit ▸▸ Inside Earth together like a giant, ball-shaped jigsaw. Tectonic plates p.135 move very slowly, just a few centimeters each year. ▸▸ Mountains p.172 ▸▸ Oceans and seas p.187 ▸▸ Volcanoes p.268 ▸▸ World p.275 Many volcanoes Tectonic plates KEY are found on the meet at plate Plate boundary Ring of Fire. boundaries. Ring of Fire Earthquakes are very Mountains common along the San Volcano Andreas Fault, a part of the The Himalayas are a mountain Ring of Fire in California. range in Asia at the boundary between two tectonic plates. Pacific Ocean The range formed over millions of years as the plates pushed Earth’s tectonic plates into each other, forcing the ground up. The mountains Earth’s surface has seven giant are still rising by about 1/5 in tectonic plates and several smaller (5 mm) every year. ones. The largest plate is below the Pacific Ocean. It covers more than 84 one-fifth of the Earth. Ring of Fire Volcanic eruptions and earthquakes are common at the plate boundaries around the Pacific Ocean. This is known as the Ring of Fire.

Earthquakes SEE ALSO ▸▸ Buildings p.48 An earthquake is when the ground shakes. ▸▸ Changing world Earthquakes happen along cracks in the Earth’s crust, known as faults. Small earthquakes can pp.50–51 barely be felt by humans, but the biggest can ▸▸ Earth’s surface cause enormous damage. p.84 What causes A fault is a crack in ▸▸ Inside Earth p.135 an earthquake? the rocks that form ▸▸ Rocks and the Earth’s crust. An earthquake happens when minerals p.214 two huge areas of the ground jerk past one another, making Powerful shaking the ground shake. The crack causes buildings to between them is called a fault. collapse, breaks up roads, and brings down power lines. The point on the ground directly above where the earthquake starts is called the epicenter. The ground on either Earthquake waves side of the fault moves travel fast outward in opposite directions. in all directions, making the ground shake. The point in the ground where the earthquake Giant waves Waves can starts is called the focus. be taller than The biggest earthquakes happen buildings San Andreas Fault under the sea. They make the sea bulge upward, forming dangerous giant The San Andreas Fault is a waves, known as tsunamis. large crack in the ground that slices through California. It Sea surface marks the join between two lifts huge pieces of the Earth’s crust, called plates. Big earthquakes happen on the fault about every 10 years. Earthquake pushes the seabed up 85

Eggs SEE ALSO ▸▸ Amphibians p.15 Some young animals grow and develop inside round ▸▸ Birds p.39 objects called eggs. There are different types of eggs. ▸▸ Fish p.101 The size of the egg and the length of time it takes to ▸▸ Life cycle p.146 hatch depends on the size of the animal that laid it. ▸▸ Mammals p.154 ▸▸ Metamorphosis p.163 Ostrich eggs are Bird eggs the largest in the world. Bird eggs are hard and waterproof. They are kept Egg-laying warm, or incubated, by one mammals of the parents. Most bird eggs are kept safe in a nest. Most mammals give birth to live babies. Only one group, It takes 42 days for called monotremes, lay eggs. an ostrich chick to The monotreme shown here be ready to hatch. is called an echidna. Ostrich chick Tortoise hatchlings are male or female depending on how warm the egg was kept. Dogfish eggs look like leathery bags, which are sometimes called “mermaid’s purses.” Fish eggs Leopard tortoise hatchling Frogspawn Most fish produce lots of eggs Reptile eggs Amphibian eggs and don’t look after them. But they do lay the eggs in places like Reptile eggs are soft and Amphibians such as frogs and sea grasses to keep them safe. leathery. The mother buries toads lay wet eggs in water. them in the ground and leaves When they are ready, the eggs them to hatch on their own. hatch and tadpoles come out. 86

Electricity SEE ALSO ▸▸ Atoms p.34 Electricity is the flow of tiny charged particles called ▸▸ Circuits p.59 electrons. It is used to power lights and electrical ▸▸ Energy pp.88–89 appliances, such as kettles and televisions, in our homes, ▸▸ Materials p.157 at school, and all around us. ▸▸ Metals p.162 ▸▸ Television p.251 Lightning Lightning is a type of natural electricity called static electricity. Tiny bits of ice in the clouds rub together, charging up electricity until a big spark of lightning occurs. Making Using electricity A toaster electricity needs Appliances like coffee electricity We make electricity pots and televisions in to heat up. from different types our homes work when of energy. One example we press a switch The light is how solar panels to connect them to bulb in this change the sun’s light electricity. Electricity lamp uses energy into electricity. flows through them to electricity. Also, wind turbines make them function. change the wind’s Wind turbines movement energy into A laptop charges up electrical energy. using electricity. 87

The story of... Fossil fuels Energy Fossil fuels are made from dead plants and animals Energy is power to make things squashed underground millions happen. It is everywhere around us. of years ago. Coal, oil, and gas Heat, light, and movement are types are fossil fuels. We burn these of energy. We need energy to make our bodies work and it’s what we use fuels to release heat and to make electricity and power our this makes electricity in homes. Energy can be stored and it can change from one form to another. power stations. Running Our bodies Your body needs energy to move, grow, keep warm, and stay alive. The food you eat gets digested and changes inside you to give you the energy you need. Movement The fastest roller Roller coaster coaster is Formula Movement is a type of Rossa in the United energy. When, for example, a Arab Emirates. It roller coaster is pulled to the travels at 150 mph top of a hill, it has lots of stored (241 kph). energy. Then as it moves downward, the roller coaster gets faster, as stored energy changes to movement energy. 88

Early steam Food chain Plants engine Deer Plants take energy from the sun’s light and convert it into sugar, a type of stored energy in plants. In this example, the deer eats the stored energy in the plants, which gives the deer Industrial Revolution energy. The lion eats the deer, and this food gives the From the late 1700s, people lion energy. began to use energy in new ways, Burning coals creating huge industrial growth. Movement energy from water turned wheels to drive machines to weave textiles in mills. Heat energy from steam engines drove trains and machines The first steam in factories. engine was developed in the 1760s by Scotsman James Watt. The sun The sun Lion Wind turbines Most of the energy we Renewable use is from the sun. The sun’s light energy changes to Renewable energy is heat energy, warming planet energy made from sources Earth. Light helps plants grow that won’t run out, such as and plants provide animals sunlight, wind, and water. For example, we can use a wind with energy. turbine or a water wheel to The wind turns turn movement energy the blades of into electricity. the turbine. 89

Elements SEE ALSO ▸▸ Atoms p.34 An element is a material that can’t be broken down ▸▸ Electricity p.87 into other materials. All objects are made from ▸▸ Gases p.117 tiny particles called atoms, which usually ▸▸ Liquids p.148 join together in groups. Elements are ▸▸ Metals p.162 pure materials, which means they are ▸▸ Gold pp.200–201 made from only one type of atom. ▸▸ Solids p.234 Elements everywhere Calcium Helium The metal calcium is The gas helium is used in Three-quarters of the elements are part found in rocks, living party balloons because it of a group called metals. They are usually things, and milk. It helps is lighter than air, so it solids that conduct electricity. Non-metal make bones, teeth, and floats. Helium is made elements include gases, such as hydrogen animal horns. inside stars. and oxygen, and solids, such as carbon and sulfur. Aluminum The soft, light metal aluminum can be made into foil, cans, and airplane parts. It doesn’t rust like some metals. The periodic table Nitrogen Gold has the The valuable The periodic table lists all symbol Ni. metal gold is found the known elements in the in its pure form in universe. There are more than Uranium nature. It can be 100 chemical elements and we has the hammered into keep finding more. All the symbol U. shapes without elements have a symbol and snapping. are placed in groups according The first periodic table, written by Mendeleev to how they behave and how Mercury is the many particles they have inside them. only metal that is liquid at room temperature. 90

Engineering SEE ALSO ▸▸ Bridges p.46 Engineers use math and science to solve problems. ▸▸ Buildings p.48 They invent and create machines, buildings, tools, and ▸▸ Factories p.97 other useful inventions that make our lives easier. ▸▸ Inventions There are different types of engineers that specialize in different areas. pp.136–137 ▸▸ Machines p.150 ▸▸ Materials p.157 Civil Chemical Civil engineers Chemical engineers design and build turn materials into structures such as buildings, bridges, useful products, including medicines. and roads. Electrical Mechanical Electrical engineers Mechanical engineers create parts for study movement, devices such as heat, and energy to computers, tablets, help them design new and mobile phones. machines and tools. Engineering process 3D printer Engineers develop older technology to make Engineers can now use new, better designs. An invention like the wheel computer-aided design has changed over time from the earliest version (CAD) programs to make to a hi-tech modern one. three-dimensional (3-D) models of their designs. one ood bber and metal The 3-D printer creates St the model using layers W of plastic. Ru 3-D printer at work 91

Engines SEE ALSO ▸▸ Aircraft p.13 Engines power machines by turning fuel into movement. ▸▸ Cars p.52 Coal, oil, or electricity is heated to create energy. The ▸▸ Factories p.97 energy is then used to turn wheels or parts that move the ▸▸ Forces p.108 machine forward. There are three main types of engines. ▸▸ Machines p.150 ▸▸ Ships p.224 ▸▸ Trains p.260 Steam engine Steam and smoke 2. Steam 1. Fire A supply of coal escape through The heat from the Coal is burned in a is stored behind The first steam engine the chimney. fire turns the metal firebox to the engine. was built in 1712 to water from liquid make a hot fire. pump water out of into steam. mines. Steam engines were used to power factories and trains. 3. Piston Steam flows into this tube where it pushes a moving part called a piston. 4. Movement The piston drives the train’s wheels forward. Car engine Jet engine Car engines burn gasoline or diesel. There are four Jet engines are used for aircraft. They work by squashing, moving parts called pistons, which move up and down, heating, and speeding up air. This hot air is blasted out making the car’s wheels turn. backward, pushing the aircraft forward. 92

Erosion SEE ALSO ▸▸ Caves p.55 Erosion is the natural movement of rocks, tiny pieces of ▸▸ Deserts p.78 loose rock, and soil, over long distances. Many different ▸▸ Glaciers p.122 things can cause erosion, including wind, rivers, ice, ▸▸ Mountains p.172 oceans, and landslides. ▸▸ Rivers p.211 ▸▸ Rock cycle p.213 ▸▸ Weather p.271 On the move Rain, snow, Landslides happen Massive flows of and ice wear when loose mountain mountain snow, Erosion moves huge amounts of rock away rock. slopes collapse. called avalanches, carry and soil, and shapes our landscape. It is loose rocks with them. fastest in mountains, where there is lots of rain and snow, and slowest in dry places such as deserts. Glaciers remove Rivers eat into valleys loose rock and and carry pieces of rock carry it down from downstream. high mountains. Coastal cliffs are The roots broken up and of plants can washed away by crack rock. powerful waves. Rock particles carried in the wind can wear away at the landscape. Wind sculptures Wind-carved rock Glacier power Over a very long period of Glaciers are rivers of ice time, tiny pieces of rock that move down from high carried by strong winds in mountains very slowly. As deserts can sandblast rocks, they move, they pick up wearing them away into rocks that scrape away amazing shapes. at the landscape, carving steep-sided valleys and hollows in the ground. 93

Europe SEE ALSO ▸▸ Ancient Greece The continent of Europe is surrounded by ocean, except in the east, where it is joined to Asia. Much of Europe is flat, p.18 but there are several high mountain ranges, including the Alps, Pyrenees, and the Carpathians. ▸▸ Ancient Rome p.20 ▸▸ Asia p.29 ▸▸ World War I p.276 ▸▸ World War II p.277 About Although it is the This powerful Europe meat-eater is second smallest the biggest Population: member of the 743.1 million continent, Europe weasel family. contains nearly 50 countries. Highest point: Wolverine Mount Elbrus Eyjafjallajökull Ferry Oil Gas Beneath the Lowest point: Coal domes of this Caspian Sea In 2010, ash from this Njupeskär cathedral in volcano in Iceland waterfall Rhythmic Moscow are Biggest desert: stopped more than gymnastics ten separate Oltenia Sahara 100,000 airline flights. churches. Longest river: Brown bear Volga Giant’s European Grass Causeway bison snake Stonehenge Little St Basil’s Mermaid Cathedral Tulips Malbork Castle The building Eiffel Golden St Sophia’s Cossack of this cathedral Tower eagle Cathedral dancing began in 1882. It is due to Dobšinská finish in 2026. Ice Cave Flamenco Sagrada Leaning Dalmatian Eiffel Tower dancing Familia Tower of pelican cathedral This iron tower in Paris Pisa Mount is 1,063 ft (324 m) high. It Olympus was completed in 1889 and is the most visited monument Mount Etna in the world. Giant’s Causeway The tower is made up of more than 18,000 The Giant’s Causeway is an area of pieces of cast iron. hexagonal columns made of ancient volcanic rock. It is on the coast of County Antrim in Northern Ireland. 94

Evolution SEE ALSO ▸▸ Dinosaurs p.80 In order to survive, an animal needs to change when ▸▸ Dogs p.81 the weather and food around it changes. This is called ▸▸ Fossils p.111 adaption. The theory of evolution is that lots of these ▸▸ Genes p.119 tiny changes over millions of years create new types ▸▸ Life cycle p.146 of living things. ▸▸ Prehistoric life Fossils p.202 Fossils are the remains of Charles Darwin living things that were alive millions of years ago. We Scientist Charles Darwin came study them to see how up with the theory of evolution life has changed. while traveling around the world investigating living things. Ammonite fossil Taller giraffes can reach more food. Giraffe Natural selection Mammals first appeared and When an animal passes on began evolving something useful on to its children, those children are 220 million more likely to survive. This is years ago. called natural selection. Selective breeding Humans can create different shapes, colors, sizes, and personalities of baby animals by choosing their parents carefully. Labrador Poodle Labradoodle (Mother) (Father) (Child) 95

Explorers SEE ALSO ▸▸ Europe p.94 Explorers travelled to new places to meet different people, ▸▸ Maps p.155 find goods for trade, or just to see what was there! They ▸▸ Exploration came from all over the world and faced big challenges on their journeys. Some were successful, such as Chinese pp.180–181 explorer Zheng He, who reached Madagascar in the 1420s. ▸▸ Navigation p.182 Others did not complete their missions. ▸▸ Ships p.224 ▸▸ Trade p.257 Frobisher tried to Europe Age of Exploration reach the Pacific, Africa but ended up in Between 1450 and 1800, new North America. navigation tools and types of ships allowed Europeans to make Atlantic Ocean long sea voyages. This period is known as the Age of Exploration. Columbus North America reached Asia America. Pacific Ocean Pacific Ocean Magellan led the first South Da Gama trip around America brought Indian the world. spices back to Portugal. Australia Indian Ocean Cook went KEY Martin Frobisher in 1576 around South Christopher Columbus in 1492 James Cook in 1770 America to get Vasco da Gama in 1498 to Australia Ferdinand Magellan from 1519 to 1521 and claim it for Britain. Trade Cinnamon Magellan Explorers discovered items Spanish sailor Ferdinand they had never seen before. Magellan set out in 1519 Merchants then traded these to find a new route to goods, such as food, spices, Asia. He left with five and precious metals. ships and 270 men, Pepper, for example, but only one ship and spread from India 18 men made it back. around the world. Black pepper Gold 96

Factories SEE ALSO ▸▸ Cars p.52 Factories are places where people and machines work ▸▸ Engineering p.91 to make things. When factories make many identical ▸▸ Machines p.150 things at the same time, it is called mass production. ▸▸ Robots p.212 Almost everything we have, use, and wear comes ▸▸ Transportation from a factory. pp.258–259 Assembly line 2. Inside and outside ▸▸ Work p.274 The frame of the car goes Things with many parts and different 3. Finished car materials are put together at various to the painting station. The completed car workstations in a factory. This is called The outside is painted, is identical to the others an assembly line. and the seats and other on the assembly line. They are all made in the same parts are put inside. way and have the 1. Bodywork same parts. Factory workers and robotic machines start building a new car by joining separate metal parts together to build a frame. Bottling factories The oranges The juice is put are squeezed. into bottles. Drinks are made and bottled in factories. The 97 same ingredients and processes are used to fill thousands of bottles every day. Oranges enter the factory.

Farming SEE ALSO ▸▸ Fish p.101 Farming is growing plants and raising animals, usually for food. Common crops include cereals, fruit, and ▸▸ Eating vegetables. Farm animals include cows, sheep, pigs, pp.104–105 chickens, and even fish. As well as their meat, cows are farmed for their milk and chickens for their eggs. ▸▸ Food p.106 Cereal farming ▸▸ Fruit and seeds Cereal crops such as p.115 wheat, corn, and barley are grown in large fields. ▸▸ Incas p.132 Rice is also a cereal. It is grown in hot countries in ▸▸ Plants p.194 water–covered areas called paddy fields. Animal farming Farmers raise pigs, cows, and chickens in large sheds or outdoors in fields. Sheep, goats, and llamas are often kept on rough or higher ground. Fruit and vegetable farming Crops such as pineapples and potatoes are grown outside. Others, such as strawberries and peppers, are grown all year round in glasshouses or plastic tunnels. Fish farming Much of the fish we eat, such as salmon and cod, is now farmed rather than caught in the wild. The fish are kept in net pens or cages in lakes, rivers, or the sea. 98