My Science School

Life is full of problems, and scientists are always trying to find new ways to solve them. There are hundreds of great scientists who have changed our lives for the better,through their discoveries and their inventions. Here are seven of them.

Evolution

Charles Darwin worked out how animals, such as moths and beetles, can change over many generations to become new species. This process is called evolution.

Computers

Ada Lovelace wrote the first published computer program. She also predicted that a computer would be able to make music and images, not just do sums.

Light bulb

Thomas Edison is best known for inventing the first light bulb that could be made in large numbers. He also invented a sound-recorder and a moving-image projector, which helped to start the age of movies.

Gravity

Issac Newton is said to have discvered how gravity works when he saw an apple fall from a tree. He realized that there must be a similar force that keeps the Earth moving around the Sun.

Radioactivity

Marie Curie discovered two substances, called radium and polonium, which give off invisible rays that can pass through materials. She called these rays radioactivity.

Relativity

Albert Einstein’s theories of relativity, along with his ground-breaking E = mc^2 equation, helped scientists to understand the Universe, and how energy, mass, space, and time are all related.

Antibiotics

Alexander Fleming discovered penicillin, which led to the creation of a group of medicines called antibiotics. They kill the bacteria that cause many infections in humans and other animal, and so have saved millions of lives.

 

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Like all vertebrates, humans have a bony skeleton underneath their skin and muscles. It is a framework to hold up the body, help it move, and protect what is inside. The amazing brain makes humans the cleverest of all the animals. That includes you!

Thinking

The brain controls the body, sorting out information from the world around you and sending out instructions. It also stores memories.

Pumping

With each beat, the heart pumps blood around the body, delivering nutrients and oxygen to every part.

Breathing

Lungs bring air into the body through breathing. This air contains oxygen, which is needed to keep the body alive.

Eating

The body needs food to survive. The digestive system breaks food down, keeping the nutrients and getting rid of the waste.

Strong muscles

Muscles are like elastic straps that can stretch or squeeze. Many muscles move the body by pulling on the bones.

Standing tall

Unlike most animals, humans walk upright on two legs. This allows the arms to be used for other activities such as making things.

Body facts

• Human skeletons contain more than 200 bones. The smallest bone is inside the ear and in only 3 mm (3/25 in) long.


• The thigh bone is the strongest bone in the body. It is about four times stronger than concrete.


• A human heart beats more than 100,000 times in a day. That is over 35 million times in a year.


• In one day, blood travels about 19,000 km (12,000 miles) around the body.

 

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There are millions of different types of animal on Earth, so scientists have divided them into groups, based on features that they share. For example, is their body covered in fur, feathers, or scales? The amazing imaginary animal shown here combines key parts of animals from six well-known groups.

Insects

All insects have six legs and a pair of feelers on their heads, like this moth. Most of them have wings and can fly.

Reptiles

Reptiles are covered in hard, dry scales, or a shell, like this tortoise. They have either four legs or no legs at all.

Mammals

Mammals have fur or hair on their bodies, and feed their babies milk. Humans are a type of mammal.

Birds

Birds have wings, and they are the only animals that have feathers, which keep them warm and help them to fly.

Fish

All fish live in water and use their tails to help them swim. Their bodies are covered in scales, and they have gills for breathing underwater.

Amphibians

Amphibians live both on land and in water. Most of them have four legs, which they use for walking and swimming.

 

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Science is all around us. From the moment we wake up to the moment we go to bed, almost everything that we do or that happens to us can be explained by science. Here are a few examples of the ways that science helps us to understand what goes on in our daily lives.

Wakey wakey!

Science explains how a cockerel could wake us up in the morning. Sound waves travel through the air from the cockerel’s mouth to our ears.

Light the way

Science explains how flicking a switch turns on our lights, by allowing electricity to flow around an electrical circuit.

Keeping warm

Science explains how our clothes keep us warm. Wool and cotton are poor conductors of heat energy, so they stop our body heat from escaping.

Eat up!

Science explains why we need to eat food every day. Food contains stored energy that we need in order to move, grow, and keep warm.

On the move

Science explains how wecan use a bicycle to travel quickly. The grip of the tyres produces friction between the wheel and the road, which helps to push the bike along.

Sun power

Science explains why a plant grows when we put it on a windowsill. Plants use energy from sunlight to produce food, which gives the plant energy to grow.

Ball games

Science explains why a ball moves when we kick, throw, or hit it. Our arms and legs produce a force that propels the ball forwards.

Time for bed

Science explains why the Moon stays in the sky. The force of gravity from the Earth pulls on the Moon, keeping it in orbit around our planet.

 

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Seeds contain everything needed to form a new plant. To do that, they need to be scattered away from the parent plant to a new place on the soil where they can grow. Different types of plant have different ways of spreading their seeds. Some need animals to move them, while others use wind or even fire to scatter them.

Blow in the wind

Some plants have very light seeds and so can use the wind to spread them. This dandelion has seeds with tiny parachutes that allow them to be carried away when the wind blows.

Tasty treats

Many plants have seeds that are hidden inside tasty fruits, such as berries. When an animal eats the fruit, the seeds pass through its body unharmed and are released in its droppings.

Sticky seeds

Animals can carry seeds away from plants without even realizing it. Sticky seeds will fix on different parts of their body, while some seeds, called burs, have little hooks that attach to the animal’s fur.

Exploding pods

The Himalayan balsam plant keeps its seeds in pods. These pods explode when they are ripe, shooting the seeds out of them. The explosion can scatter the seeds up to 7 m (22 ft) away, often startling unsuspecting passers-by.

Earth, wind, and fire

Some plants have more dramatic or unusual ways of spreading their seeds. Fire may kill the parent plants, but it leaves behind fertile ash for their seeds to grow in.

Heat treatment

Jack pine cones are glued shut with resin. When a fire sweeps through the trees, the resin melts and the seeds are released.

Desert rover

Tumbleweed is the dried-up top part of some plants. It rolls around the desert whenever the wind blows, scattering its seed as it goes.

 

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Plants make their own food using sunlight. Most plants are held in the ground by their roots, and have green leaves. There are thousands of types of plants, ranging from huge oak trees to small ones like this fuchsia.

Roots

Plants usually grow in the earth or soil. The roots dig deep into the ground, keeping the plant in place. They also soak up mineral salts and water from the soil.

Stem

The stem supports the leaves and flowers holding them up towards the light. The stem also carries water and nutrients in the form of mineral salts from the roots to the rest of the plant.

Leaves

Plants use their green leaves to capture energy from the Sun’s rays. The leaves use this energy, together with carbon dioxide from the air, and water, to make food for the whole plant.

Flowers

Most plants have flowers for reproduction. They have male pollen and female eggs, which join together to make seeds.

Berries

Fruits, such as berries, are the parts of flowering plant that contain seeds. Once in the ground, the seeds will grow into new plants.

Why we need plants?

Nearly every animal relies on plants in some way or other. Some animals, called herbivores, eat only plants. Human grow lots of types of plants just for their flowers. Some types of tree are grown for their wood.

 

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All living things have certain characteristics in common. To count as being alive, a living thing has to be able to carry out seven different processes, which are listed below.

Movement

All living things can move on their own. Even plants have leaves that turn to face the Sun.

Reproduction

Living things can produce new versions of themselves.

Sensitivity

Living things can detect and respond to changes in the world around them. For example, the ability to react to changes in light, or to hear sounds.

Growth

Living things get bigger as they get older until they reach their full size.

Respiration

All living things turn food into energy, using oxygen from the air.

Excretion

All living things must get rid of any waste that they produce.

Nutrition

All living things need food. Unlike animals, plants make their own food.

Animal

Animals can move from place to place. They cannot make their own food, so they rely on eating other living things to survive.

Plant

Plants are fixed in the ground, but their roots, leaves, and flowers can move. They make their own food by using the Sun’s rays.

Fungus

Funguses may not look alive, but they are. Most funguses feed on the remains of dead plants or animals. Mushrooms, toadstools, and moulds are all funguses.

Tree trunk

When a tree dies it usually falls to the ground. Funguses can grow on the dead tree trunk and soak up its nutrients.

 

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Magnets are objects that produce an invisible force called magnetism. When two magnets are close to each other they produce pushing or pulling forces on one another. Magnets can also pull on, or attract, other objects that are made of magnetic materials, such as iron. Magnets are often U-shaped, like a horseshoe.

Magnetic poles

Magnets have two ends, or poles, called a north pole and a south pole. Unlike poles pull on each other, or attract, so a north pole pulls a south pole. Like poles push on each other, or repel, so a north pole pushes another north pole away.

Magnetic materials

Iron is a magnetic material, so any metal with iron in it, such as steel, will be attracted to a magnet. Nickel and cobalt are also magnetic metals.

Non-magnetic materials

Magnets have no effect on non-magnetic materials. Non-magnetic materials include all non-metals, such as glass, plastic, or wood. Most metals are also non-magnetic, including gold, aluminium, and copper.

 

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An electrical circuit is a loop around which electrical energy can move. Electricity travels from a power source, such as a battery, through wires, and back to the power source. In a simple circuit, other useful items that make use of the electricity, such as a bulb or a buzzer, are added. Electricity can only flow when there is a complete circuit.

Battery

A battery stores electrical energy and releases it when connected to a circuit. The battery will eventually run down and will have to be replaced.

Switch

A switch allows the bulb to be turned on or off without removing the battery. When the switch is closed, the circuit is complete and the bulb lights up.

Wires

Electricity flows around the circuit through a series of wires. Wires are usually made of copper, as copper is a good conductor of electricity.

Bulb

As electricity flows through the bulb, the electricity energy is converted to light energy, and the bulb glows brightly.

Conductors and Insulators

Conductors allow electricity to flow easily through them. Metals, such as copper, are good conductors of electricity. Electrical wires are made of metal so electricity can flow easily through them. Insulators do not let electricity pass through them. Plastic, rubber, and wood are good electrical insulators. Wires are coated in plastic to prevent you from getting an electric shock if you touch them.

Switching on!

Many electrical items do not need batteries as they can be plugged into the mains, using a long wire. Once they have been plugged in, these items are usually turned on by passing a switch, which completes the electrical circuit.

 

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Electricity is a type of energy that can either flow from one area to another or build up in one place. Humans have invented ways of capturing other forms of energy and using them to make electricity. Many things in our homes, such as lights, are powered by electricity.

Into our homes

After electricity has been made by a power station, it travels to towns and homes along a series of underground or overground cables. The electrical cables send electricity into the plug sockets found in most buildings. This is called mains electricity.

Static electricity

Sometimes electricity energy builds up in one place. This is called static electricity. The build-up can happen when things are rubbed together, like a balloon and a jumper, which can cause them to stick together. When a build-up of electrical energy is released, a spark of electricity can sometimes be seen or felt.

Lightning

A lightning bolt is a giant spark of electricity. When rain clouds rub against the air around them, static electricity builds up. If the build-up gets big enough, the electrical energy leaps to Earth as a bolt of lightning.

 

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We usually see light as white, but it is actually a mixture of different colours. We know this because we can see the colours in a rainbow. When the Sun is shining low in the sky behind you and rain is falling in front of you, you may see a rainbow.

The colours of a rainbow

The colours always spread out in the same order. We call the pattern they make a spectrum. The seven main bands of colour blend into each other, creating millions of different colours.

Seeing a rainbow

As sunlight passes through a shower of raindrops, it bends and splits into different colours.

Double rainbow

If the sunlight is reflected twice inside each raindrop, you can see a see rainbow outside the main one, with its colours in the opposite order.

Colour arc

Rainbows are curved because the colours leave the raindrops at different angles.

Bright colours

Large raindrops from bright, clear rainbows, while small raindrops make faint, fading ones.

Is it the end?

If the ground wasn’t in the way, you would see the rainbow as a circle.

Inside a raindrop

Rays of sunlight shine towards the falling raindrops. When a ray enters a raindrop, it bends and the white light spreads into different colours. The light reflects off the back of the raindrop. When the light leaves the raindrop it bends again, so the colours spread out even more and shine down towards your eyes.

 

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Light is a type of energy that allows us to see things. Light travels as rays, in straight lines. Light rays are given off by things that glow, such as the Sun, a candle, or a light bulb. These things are called light sources. Other objects around us look bright because they bounce light from light sources back to our eyes. When there is no light source everything looks dark, for example at night.

Seeing things

Most things do not give out their own light. We can see these objects when we look at them because they reflect the light that falls on them. Light from a light source, such as the Sun, bounces off the object and into our eyes.

Creating shadows

If something solid gets in the way of light coming from a source, the light rays are blocked. This creates a shadow behind the object, which is the same shape as the object.

Shadow length

The length of the shadow of an object can change, depending on where the light source is. The more directly above an object a light source is, the shorter the object’s shadow will be.

Midday

At midday, the Sun is almost directly overhead. The light rays from the Sun can reach most of the ground on the far side of the ball, forming a short shadow.

Late afternoon

By late afternoon, the Sun is low in the sky. The light rays from the Sun are blocked from reaching a large area of ground on the far side of the ball, so a long shadow forms.

 

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Vibrations with lots of energy produce big waves and make loud sounds. So, banging a drum harder will produce a louder sound. Sound waves lose energy as they travel, which means that the further you are from a sound, the quieter it will be.

Rustling leaves

When leaves brush against one other, they produce tiny vibrations in the air. These vibrations only have a small amount of energy, so the rustling sound is very quiet.

Roaring lion

A lion’s roar causes the surrounding air to vibrate with lots of energy. It produces a loud sound, which can be heard up to 8 km (5 miles) away.

Rocket launch

When a rocket launches, the exploding gases produce huge amounts of sound energy. The noise is louder than 10 million rock bands performing at once!

 

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Sound is produced when things vibrate, or shake. A vibrating object makes the air next to it vibrate as well. These vibrations travel through the air as a sound wave, which we hear with our ears. Sound waves can also travel through liquids and solids, such as water, rock, or wood.

Making sound

When the climber hits the metal spike with his hammer, it vibrates. This vibration causes the surrounding air to vibrate too, producing a sound wave.

Sound wave

The sound wave spreads out through the air. It travels away from the rock and hammer until it reaches a solid surface.

Reflection

When the sound wave hits a solid surface, such as the side of a cliff, some of the energy becomes back towards the climber. The rest of the sound energy travels through the rock.

Echo

The climber will hear the reflected sound wave as an echo, a few moments after he first produced the sound.

 

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Heat is a type of energy that we can feel. The hotter something is, the more heat energy it gives out. Heat energy always tries to spread from a hotter to colder things. So, when you touch a hot object, heat energy flows out of the object into you, warming you up.

Conduction

Heat energy spreads out through solid objects by conduction. Metal objects are very good conductors of heat, so heat energy pass through them quickly and easily.

Convection

When gases and liquids get hot, heat energy spreads out through them by convection. Hot air or water rises, and cold air or water sinks to take its place.

Radiation

Heat escapes from the surface of hot objects by invisible rays that travel through air and space. This is how we feel the heat from the Sun. hotter objects give out more radiation than cooler ones.

Temperature

Temperature is the measure of how hot or cold things are. It is recorded in degrees Celsius (ºC) or degrees Fahrenheit (ºF).

15 millionºC (27 millionºF)

The temperature at the centre of the Sun.

1760ºC (3,200ºF)

The temperature at which sand melts and turns into glass.

232ºC (450ºF)

The temperature at which dry wood catches fire.

100ºC (212ºF)

The boiling point of water.

56.7ºC (134ºF)

The hottest temperature recorded on Earth at Death Valley, California, USA, on 10 July 1913.

37ºC (98.6ºF)

The average temperature of the human body.

2ºC (35.6ºF)

The temperature of the air when rain turns to snow.

0ºC (32ºF)

The freezing point of water.

89.2ºC (-128.5ºF)

The coldest temperature recorded on Earth at Vostock Station, Antarctica, in 1983.

-272ºC (-458ºF)

The temperature of the Boomerang Nebula, a cloud of dust and gas that is the coldest place in the Universe.

 

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