Plants provide us with food, building materials, raw resouces used in manufacturing processes, fuel and life-saving drugs, as well bringing colour, scent and beauty into our lives. Plants also play an essential role in maintaining the environmental sustainability of the earth.
Cultivating and looking after plants are ideal ways for young children to be introduced to the importance of caring for living things and their responsibility for taking care of the planet.
What do I need to know?
This information provides you with some of the background knowledge that you need to support young children's scientific learning. Use this information to help you to provide experiences and ask questions which will help the children to build their own scientific understanding.
Classification of plants
Plants come in a huge variety of shapes and sizes. The structure of different types of plant has adapted over a long period of time to suit the environment in which the plant grows. Desert plants, for example, often have very thick, succulent leaves to store water. Trees growing in dense forests grow tall in order to reach the light, and bushes in windy places are small and stunted to prevent their branches being broken in the wind.
The plant kingdom ranges from very simple plants such as algae, lichens and mosses, to more complex structures including ferns and horsetails, up to the largest group of all, which are called spermatophytes - plants which produce seeds. The spermatophytes are subdivided into two groups, conifers and flowering plants, with which we are familiar.
Parts of a plant
Flowering plants come in a huge variety of shapes and sizes. They have different coloured and shaped flowers and have leaves that differ in shape arrangement, texture and colour. All plants have the same basic structure - roots, stem, leaves and flowers.
* Roots The roots are the part of the plant which is normally underground.
Their function is to anchor the plant firmly so it doesn't fall over as it grows, and to draw up water from the soil.
If you look carefully at the roots of some plants, you will be able to see the tiny root hairs that absorb water from around the soil particles. This water then travels in a system of tubes inside the stem of the plant to the leaves.
The cells of the plant need this water to keep them swollen up and pressing against each other. This is what gives a plant much of its shape and explains why a plant droops and wilts when it isn't watered.
* Stem and leaves The stem and the leaves of the plant are the places where the plant makes its food. Some stems are thick and strong and upright, others are thin and flexible and can bend easily so the plant can climb over and around things.
The leaves may be small or large, but they are always arranged on the plant to give maximum exposure to the light. In spring, try standing underneath a sycamore or horse chestnut tree and looking upwards - notice how the branches and leaves are arranged to face the light.
* Flowers Some plants have large, colourful, scented flowers and others have tiny flowers that are almost insignificant. The flower is the reproductive part of the plant and contains male and female parts. The male parts are called the stamens and produce pollen. The female parts are called the carpel and contain ovules, which, when fertilised, turn into seeds.
Pollen from the male parts of the plant is transferred to another flower by the wind or by insects. Plants that rely on insects for fertilisation have brightly coloured, scented flowers and produce a sugary substance called nectar to encourage insects to visit them.
Once a flower is fertilised, the petals die off, the seeds start to grow and the seed case swells and sometimes hardens to protect the seeds. When the seeds are ripe they are ready to be distributed in different ways to start growing into new plants again.
Seeds such as dandelions travel on the wind, Busy Lizzies have exploding seed pods that shoot seeds out, and blackberry seeds have a sweet juicy covering which birds will eat and deposit in their droppings.
How plants grow
Plants are the only living things that can make their own food using energy from the sun. They do this by using energy from sunlight to convert carbon dioxide from the surrounding air and water into carbohydrate. This process is known as photosynthesis. It uses a chemical called chlorophyll which is found in all the green parts of the plant.
Animals are not able to do this and have to rely on plants, directly or indirectly, as the primary source of food energy. Some animals, such as cows and sheep, eat plants; other animals, such as lions, eat smaller animals; and some animals, including humans, eat both plants and animals.
Children often become confused when we talk about 'feeding' plants to help them grow. Plant 'food' or fertiliser contains minerals and nutrients which we use to help plants to grow stronger or larger, but it is not essential for plant growth.
Investigating
Looking at flowers
Organise an activity that encourages children to notice flowers in their environment and to observe closely their different shapes and structures.
What you need
Magnifying glasses or sheet magnifiers; access to outdoor area where a variety of flowering plants are growing; drawing pencils and paper What to do
- Discuss the importance of handling the plants gently and ask questions such as: How many different types of flowers are there? What shape is each of the flowers? How many petals do the different flowers have? Are the petals individual (as in a daisy), or are they joined to one another (as in a daffodil)? What colour are the petals? What colour is the centre of the flower?
- Make a simple record or tally sheet of the numbers of the different plants.
- Help the children to use the magnifiers to look closely at the structure of the different flowers.
- Encourage them to draw the flowers and talk about what they look like.
Shapes, textures and patterns
Provide opportunities for children to handle simple tools, observe carefully and use descriptive language about shape, texture, pattern and symmetry.
What you need
Hand lenses or a large magnifier; seeds and seed pods that the children have collected themselves, such as conkers, sweet chestnuts, acorns and sycamore seeds; vegetables such as peas and broad beans in their pods; exotic seed pods found in garden centres; fine-tipped colouring pens or coloured drawing pencils
What to do
- With the children, talk about your collection of seeds and seed pods. What shape are the seed pods? What do they feel like? Which ones are smooth and which ones are spiky or rough? Where are the seeds? What do they feel like? Do they have any patterns on them?
- Use the hand lens to look more closely at the seeds and seed pods.
- Encourage the children to describe their seeds and seed pods and to make drawings of them.
- Make a display of the seeds and seed pods, the children's drawings and the words that they used to describe what they were seeing.
Vocabulary to introduce
plant soil petal
root water colour
stem light seed
leaf green soil
flower grow sun
Linda Thornton and Pat Brunton are education consultants with a special interest in science and technology for young children. Contact them at www.alcassociates.co.uk
