DK Children’s Encyclopedia ( PDFDrive )

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