My Science School

 

 

 

All living things need water. Plants drink by sucking up water with their roots. Water travels up the stem to the leaves. If a plant does not have water the stem will go floppy. The leaves and stem will dry out and the plant will die.

 

 

 

 

 

 

Plants need a little water, but not too much.

If plants do not have water they dry up and die. Indoor plants need to be watered, but too much water can be bad for them. If they are too wet the plants will rot. A plant’s roots have thin ‘hairs’ at the end of them. It is these root hairs that absorb water. The main roots then carry the water up to the plant.

 

 

 

 

 

 

 

In summer, people may need to water plants that grow outside.

Plants lose water through their leaves. When the weather is warm and dry, plants lose more water than usual. They need to drink extra water to stay alive. If there is too little rain, gardeners need to water their plants.

 

 

 

 

 

 

 

See how plants drink! The water travels up the stem to the leaves.

Put a few drops of food colouring into a glass of water. Ask an adult to cut a stick of celery. Put it in the coloured water. Look at the celery after 30 minutes. Does the coloured water move up the stem toward the leaves? Cut the celery in two. Can you see the tubes holding the water?

 

 

 

 

 

Plants need sunlight, air and water. Most plants have roots to hold them in the ground and to suck up water. They have stems to hold up their leaves. Most plants have green leaves. They use their leaves to make food.

 

 

 

 

 

 

This plant has roots a strong stem, and green leaves.

All living things, including plants, have seven things in common. They are – feed, move, breathe, get rid of waste products, and grow, sensitive to things like light and heat, and they make new versions of themselves.

 

 

 

 

Continue reading "Plants are living things"

Some plants are so small they are hard to see. Some are so big they seem to touch the sky. Plants grow in many places. If you look you will find plants around your home and school, as well as in parks and in the country.

Here are some tiny plants and a very tall tree

Plants have been on planet Earth for 400 million years. They even existed before dinosaurs! Today, scientists think there are as many as ten million different kinds of plants. Some plants die after a few days and others live for hundreds of years.

 

 

 

 

 

 

 

 

 

 

Continue reading "The plant world"

 

Wood is a valuable material that is used every day all over the world. Trees give food and shelter to many animals and clean the air we breathe. It is important to look after trees. We can do this by caring for forests and by recycling paper.

 

 

 

 

 

 

Everyone must care for our world’s forests.

Wood that comes from a well-managed forest is sometimes labelled so that we know the forest is sustainable. This means that when trees are harvested more trees are planted in their place. If we look after trees and replace the ones we cut down we will never run out of wood.

 

 

 

 

 

 

 

 

Recycling one tonne of paper saves 17 trees.

Millions of trees are cut down each year to provide the raw material for making paper. Logging destroys habitats that are full of plants and animals. By recycling our waste paper, we can help to protect natural habitats and save trees. We can all help to save trees by recycling our waste paper and by buying products made from recycled paper.

 

 

 

 

 

 

 

This symbol tells us if something can be recycled.

 

 

Trees are very important for all the life on Earth. They help control the world’s weather and clean the air we breathe. They provide homes and food to many different animals. We need trees for life.

 

 

 

 

 

These rainforest trees give us oxygen.

Trees and plants remove carbon dioxide gas from the Earth’s atmosphere. They use it to make their food and release oxygen back into the air. Rainforests recycle huge amounts of air. Many rainforests are being cut down and may disappear. We must preserve them as they are so important for cleaning the air.

 

 

 

 

 

 

This fungus is growing on a tree.

When a tree dies a fungus may use it for food. Fungi feed and grow on the dead wood. They make the wood slowly rot away and help to recycle the wood’s nutrients back into the soil. The nutrients are then re-used by other plants.

 

 

 

 

 

 

Many insects feed on rotting wood.

Rotting wood provides food and shelter to many animals. Some beetle larvae burrow into the wood as they feed. Woodlice feed on the larvae. Woodpeckers feed on the woodlice and other wood-eating insects.

 

 

 

 

Many animals use wood. Some use it as a building material to make their homes. Other animals eat wood. Animals like woodworm sometimes eat the wood we use inside our homes and leave it full of holes. They can harm whole houses.

 

 

 

 

 

 

 

 

Termites can also damage wooden houses.

Most animals can’t eat wood because it contains tough cellulose. Termites can eat wood because they have tiny creatures inside their gut which digest the cellulose for them. Termites live in the ground and dig tunnels into trees or wooden buildings. In some countries they are a problem because they damage wooden buildings.

 

 

 

 

 

 

 

 

This wasps’ nest is made from wood fibres.

Wasps use wood to make their delicate paper nests. They scrape wood from wooden sheds or fence posts and chew it into a pulp. Then they shape the pulp into a nest. When the pulp dries out it hardens into paper.

 

 

 

 

 

 

 

 

 

Beavers use wood to build their homes.

Beavers cut down trees and use them to dam up streams and create a new lake. They use the trees to build a safe home, called a lodge, in the middle of the lake. They store branches under water and then eat them in the winter.

 

 

 

Most of the conifer trees grown in plantations (tree farms) are used to make paper. Paper is made by squashing, mixing and drying small wood fibres. You can see the tiny fibres when you tear a piece of paper.

 

 

 

 

 

 

 

 

Wood chips are made into paper at a paper mill.

Paper is made at a factory called a paper mill. At the paper mill, logs are cut up into small wood chips. They are then squashed and pulped in machines until the wood is soft and spongy. The pulp is then mixed with chemicals to make a wet sludge.

 

 

 

 

 

Paper is made into huge rolls.

The wood fibres in the sludge are squashed together and pressed into thin sheets of paper. Rollers squeeze out the water and the paper is dried and wound onto huge reels ready for use.

 

 

 

Continue reading "Paper – making "

 

 

Many of the foods and medicines we use come from rainforest trees and plants. It is important to look after our rainforests, because many more useful medicines could be found in them in the future.

 

 

 

 

All these things come from rainforests.

Lots of the foods that we eat come from rainforest trees and plants. Plants like pineapple, coffee and banana first grew wild in rainforests and are now grown on large plantations. Brazil nuts are still collected from trees growing in the rainforest.

 

 

 

 

 

 

 

 

Continue reading "Wood for medicine and food"

 

 

Many people all over the world use wood for burning. Wood is a source of energy. When it burns, it gives out heat and light. People collect wood and use it to cook their food and to keep warm.

 

 

 

 

 

 

 

This meal is being cooked on a wood fire.

In some places people cook food in a pot balanced over the flames of an open fire. As wood burns, it gives off smoke and grows smaller until all that is left is a grey ash. Wood smoke can pollute the air. To reduce this pollution, it is better to burn dry hardwood as it gives off less smoke than ‘green’ wood.

 

 

Continue reading "Wood for fuel "

 

 

 

Wood is a very useful material and is used to make many things. It is easy to cut into different shapes. It can be smoothed and polished. Objects made from wood can last for hundreds of years if they are looked after.

 

 

 

 

 

 

 

A carpenter’s tools help to shape the wood.

A person who makes things with wood is called a carpenter.

Carpenters use tools to make wood into many different things such as furniture, toys and houses. The carpenter uses special tools such as saws, drills and chisels to cut and shape wood. They smooth wood by using sandpaper.

 

 

 

 

 

Baskets are made from long, thin pieces of wood.

Thin branches of wood such as willow and hazel can bend easily. They are used to weave baskets of all shapes and sizes. Before weaving, the thin branches are soaked in water to help them bend easily and take shape.

 

 

 

 

 

These boats are made from tree trunks.

Wood can float and is often used to make boats. People who live by rivers in rainforests make boats from whole tree trunks. They cut down a straight tree and remove the bark. Then they hollow out the tree trunk by carefully burning the wood a little at a time. Finally they carve it out with tools. These boats are called dug-out canoes.

 

 

After the trees are cut down they are taken away. Most logs are carried out of the forest on special Lorries or trains. They are taken to a sawmill. At the sawmill, huge saws can quickly cut up large tree trunks.

 

 

 

 

 

 

Animals can be used to pull logs out of the forest.

In some forests, big machines cannot be used. In these places animals, such as horses or elephants, are used to transport logs out of the forest. The animals can easily move between growing trees and do not harm the environment.

 

 

 

 

 

A saw cuts the tree into planks.

At the sawmill the bark is trimmed off and the logs are cut into planks. Logs can be cut in different ways to give different grain patterns. Hardwoods can be cut into thin slices called veneers. Veneers are used to decorate objects.

 

 

 

 

 

 

These planks are drying.

The cut planks cannot be used straight away because they still contain a lot of sap. Sap is the liquid or juice inside the wood. Freshly cut wood is called ‘green’ timber and needs to be dried out so that it will not twist, bend, crack, or shrink when it’s used. Drying the wood is called seasoning.

 

 

Most of the wood we use is specially grown in large forests. These forests are carefully planned to help the trees grow well. The kinds of trees planted are the ones that will grow best in the forest’s soil and weather.

 

 

 

 

These baby trees are growing in a tree nursery.

Conifer tree seeds are collected from pine cones in the autumn. Before they are planted, the hard seed coats are rubbed with sandpaper to help them grow quickly. The seeds are planted in paper containers and kept in a nursery to protect them from mice, birds and frost. Young trees are called saplings. They stay in the nursery for three years.

 

 

 

 

 

Trees are often planted by hand.

Before saplings are planted out, the soil is prepared with a digger or plough. The trees are planted close together to help protect them from the wind. Sometimes a fence is put up to stop deer or rabbits from nibbling the saplings.

 

 

 

 

 

When trees have grown big enough, they are cut down.

Conifers are cut down when they are 50-70 years old. Broad-leaved trees are left until they are 100-150 years old. Some trees are cut down by a woodcutter, or lumberjack, using a chain saw. Others are cut down with a harvester machine.

 

 

 

 

Each year a tree grows a new layer of wood. The rings inside a tree trunk show each year’s new growth. If you count the rings you can find out how old the tree is. This tree is probably older than you.

 

 

 

 

 

 

Knots show where a branch grew out from the tree trunk.

The fibres make a pattern of lines called the grain. If the lines are close together, the wood is a hardwood. Broad-leaved trees have hardwood which is close-grained. If the lines of the grain are wider apart, the wood is open-grained or softwood. Conifers produce softwood.

 

 

 

 

 

 

 

 

Some wood is very strong.

Trees and other plants make a substance called cellulose. Cellulose forms into strands which mat together and make up the walls of tiny cells inside the tree. The cellulose is very important as it makes wood strong.

 

 

 

 

 

This board game is made from different colour woods.

Each type of tree has different coloured wood. Pine trees have a pale wood and walnut has a dark brown wood. A mixture of different colours of wood is sometimes used to decorate furniture.

 

The wood we use comes from two types of trees. One type is called broad-leaved trees and the other type is called conifers. Broad-leaved trees grow slowly and have hard wood. Conifers grow much faster and their wood is usually softer.

 

 

 

 

 

 

This oak tree is over 100 years old.

Broad-leaved trees such as oak and maple have wide leaves. Most broad-leaved trees are deciduous, which means they lose their leaves in the autumn. Broad-leaved trees usually grow in mild climates, but some grow in tropical rainforests. Timber from broad-leaved trees is known as hardwood.

 

 

 

 

 

Most of our wood comes from conifers.

Conifer trees have needle-like leaves and grow well in cold conditions. They are grown in large forests called plantations. Plantations are like tree farms. The timber from conifer trees is called softwood.

 

 

 

 

 

Wood from conifers is used to build houses.

Fast growing softwood trees like Scots pine are used to make telegraph poles and the frames for some houses. Timber from slow growing hardwoods, such as oak, is used for making furniture.

 

 

 

 

Wood is an amazing natural material. It is used every day all over the world. Wood is used to make many things. It was even used to make this book you are reading!

 

 

 

 

 

 

 

 

 

Wood is found under the bark of trees.

Wood comes from inside the trunks and branches of trees. The outside of a tree is covered with bark, which is like the tree’s skin. The bark protects the wood on the inside from being attacked by insects, fungi and animals. Each kind of tree has its own special bark pattern, texture and colour.

 

 

 

 

The dolls and the violin are made from wood.

Wood is strong, springy and warm to the touch. It can be cut, carved, shaped and coloured. Wood is used to build houses and to make furniture. Many musical instruments are made from wood.

 

 

 

 

 

 

 

 

Continue reading "What is wood?"