G42 Plants for classrooms

G42 Plants for classrooms
Plants for classrooms
G42
June 2009
June 2009
Contents
1.0 Why keep plants in school?................................................................................... 1
1.1 Common misconceptions.................................................................................................... 1
2.0 Plants and the curriculum...................................................................................... 5
2.1 Science in the National Curriculum for Wales..................................................................... 5
2.2 Science and Technology in the National Curriculum for Northern Ireland .......................... 5
3.0 Caring for plants ..................................................................................................... 6
3.1 Safety code for classroom and other plants........................................................................ 6
4.0 An alphabetical list of suitable classroom plants ................................................ 7
5.0 Poisonous plants .................................................................................................. 10
6.0 Activities with plants ............................................................................................ 11
6.1 Some twists on growing plants ......................................................................................... 13
7.0 Classroom resources ........................................................................................... 16
7.1 Models of plants and flowers ............................................................................................ 16
7.2 Picture and poster packs .................................................................................................. 16
7.3 Cultivation in the classroom .............................................................................................. 17
7.4 Garden tools ..................................................................................................................... 18
7.5 Root propagation gel ........................................................................................................ 18
7.6 Root windows / observation tanks .................................................................................... 18
7.7 Miniature greenhouses ..................................................................................................... 18
8.0 Resources...............................................................................................................19
8.1 Primary plants................................................................................................................... 19
8.2 Growing Schools............................................................................................................... 19
8.3 Get your hands dirty ......................................................................................................... 19
8.4 The Biotechnology and Biological Research Council (BBSRC) ........................................ 19
8.5 Learning through landscapes............................................................................................ 20
8.6 The AstraZeneca Science Teaching Trust........................................................................ 20
8.7 The Royal Botanic Gardens, Kew..................................................................................... 20
8.8 The Field Studies Council (FSC) ...................................................................................... 21
8.9 Gatekeeper guides ........................................................................................................... 21
8.10 Teachers TV ................................................................................................................... 21
8.11 4Learning........................................................................................................................ 21
9.0 Beekeeping............................................................................................................ 22
© CLEAPSS 2009
Strictly Confidential
Circulate to members and associates only
As with all CLEAPSS materials, members and associates are free to copy all or part of this guide for
use in their own establishments.
CLEAPSS
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E-mail: science@cleapss.org.uk
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G42 Plants for classrooms
1.0 Why keep plants in school?
This is a question that many children might ask. At first sight plants are dull, slow to change and don’t
appear to do anything. A number of common misconceptions surround what plants are and what plants
are for. Without green plants there would be few animals, and certainly no humans, on Earth. Let’s start
with one or two misconceptions that children may have.
1.1 Common misconceptions
Trees aren’t alive. Students should be taught the differences between things that are living and things
that have never been alive.
It is not uncommon to believe that trees are not alive. They appear to have stood forever; they appear
to be unchanging and they don’t react as animals do. This misconception may be behind vandalism of
trees. They may seem no more alive than lampposts.
Recording the changes in a tree over a year corrects this false idea. Trees flower and fruit and if they
are deciduous they lose their leaves. Even evergreens lose and replace their needles. A series of
photographs – or drawings – made over a period of months telescopes these changes. Trees are living
– and growing.
(‘Tall fescue’)
Only ‘flowers’ are plants. Trees flower and so does grass – both are green plants. Many tree flowers
are small and discreet. Grass flowers, being wind-pollinated, don’t need to be brightly coloured and so
may resemble green tassels.
When children are asked to name plants they usually chose those with large colourful flowers. They are
more likely to name pot plants – and to draw them – than plants growing in natural surroundings.
Plants don’t ‘do’ anything. Children may consider plants so dull that they can’t even name many of
them. If they are asked about habitats they will name animals – but few plants. Yet plants grow and
change and they even move (with some exceptions) very slowly. Plants growing near windows align
their leaves with the sunshine. Balancing the light by putting a mirror behind them makes them grow
more upright.
Some plants do move relatively quickly. The sensitive plant (Mimosa) and carnivorous plants respond
to touch or chemical stimuli, but all plants react to external stimuli. The tendrils on broad bean plants
react to touching a support by twining round it. The roots of germinating seeds react to gravity by
growing downward. If the roots are inverted they loop to grow down again.
1
Plants are made from soil. Photosynthesis is the process by which green plants harness the sun’s
energy to combine very basic raw materials – water and carbon dioxide – to make sugars. These
provide all the energy that plants need to live, grow, repair themselves and to reproduce.
These sugars are further combined and changed to make the structure of plants. With the exception of
water, some carbon dioxide and tiny amounts of mineral salts, plants do not need to draw anything from
the soil. Cuttings continue to grow if simply put in water. There is no other input and yet the cuttings get
larger.
Plants need food. Fertilisers are sometimes confusingly labelled ‘plant food’, which can lead children
to think that these supplements are the equivalent of a meal. Plants do need tiny amounts of mineral
salts for their health and these are commonly available in fertile soil. Poor soil can be enhanced using
tiny quantities of chemicals.
Plants don’t breathe. Strictly, no they don’t. Breathing is the mechanical process of drawing air into
the lungs. However, plants do respire. They release energy from sugars using oxygen and produce
water and carbon dioxide as waste products. They respire all the time, like animal, but unlike animals,
they manufacture their own food in sunlight.
All leaves are green. This is not true. Some leaves are variegated so that only parts of the leaf are a
rich green. The green colour in leaves is a pigment called chlorophyll, which is essential for
photosynthesis. All leaves contain chlorophyll although other pigments – red or brown – may mask it.
We don’t need plants . They may be very pretty, but do plants serve a useful purpose? All life on Earth
depends on green plants. They are the food source of all herbivores, which are in turn the food source
of carnivores. Plants are also the source of many other essential materials – eg, fuels, fabrics and
furniture.
Plants draw carbon dioxide from the atmosphere and as a result they reduce the build-up of this
greenhouse gas. However, burning fossil fuels – the remains of plants that lived long ago – releases the
stored CO2 and adds to the problem. Clearing forests also reduces the number of plants available to
use the CO2. A combination of burning fossil fuels and destroying forests by ‘slash and burn’ adds to
the greenhouse gases in the atmosphere.
Fungi are plants. Fungi now belong in a separate grouping to plants. At one time they were considered
to be a type of plant, but they can’t make their own food and their structure is not made up of cellulose.
2
Bees fertilise all the flowers. Not just bees! Plants have a number of ways of ensuring the
continuation of the species. Green plants are not able to pull up their roots and go out to seek a mate.
That means they have to rely on other distribution techniques, both for the male sex cells – carried in
pollen and for the fertile seeds. As a result, they reproduce in a variety of ways.

Runners and roots
Some plants reproduce asexually. For example, the runners that grow from strawberry plants touch the
ground, root and grow into new plants. Daffodil bulbs split and two plants grow where there was once
one. This does not preclude sexual reproduction. Strawberry plants flower and of course fruit. Daffodils
also flower and produce seeds.

Blowing in the wind
Many plants reproduce by releasing clouds of pollen into the air, as hay fever sufferers are well aware.
The pollen floats and may encounter the stigma of another plant. These plants do not need colourful
flowers to attract insects, but they may have long, feathery flowers increasing the chances of trapping a
passing pollen grain. Grasses and some trees disperse their pollen on the wind.

Insect couriers
Green plants with brightly coloured flowers are aiming to attract, by colour, scent and edible bait, a
passing insect or other mobile animal that will carry their pollen to another flower. Honey guides – fine
lines on petals invisible to human eyes but visible to insects – guide bees and other insects to nectar
stored at their base. Pollen, accidentally carried by these visitors is brushed onto the stigma of other
flowers to ensure cross-fertilisation.

Self-preservation
If all else fails, many flowers can self-pollinate. The male anthers curl in to brush pollen on the stigma of
the same flower.
3
Seeds drop to the ground. New plants growing alongside parent plants compete with them for space
and resources. They also fail to invade new territory, making the species vulnerable to disease or forest
fire. Seed dispersal is critical and plants have adapted to achieve this in many different ways.
Seeds can be blown or carried by water, can attach to animals or pass through their gut unharmed, or
may be projected by an ‘explosion’. Some seeds simply fall to the ground close to the parent plant. This
suggests that – like maize and wheat – they depend upon human intervention.
Some seeds seem to defy the ideas of dispersal. For example, coconuts – sometimes sold in their thick
fibrous husks – have adapted to floating to new habitats. Avocado seeds may once have been
intimately linked with megafauna – now extinct. These were huge animals that could both swallow and
pass the seeds. Fortunately, the Resplendent Quetzal bird is still able to swallow whole avocados,
digest the flesh and cough up the stone.
Seeds can’t germinate in the dark. You might assume that a seed ‘shoots’ before it ‘roots’. However,
it stands to reason that if it is to secure itself and begin to absorb water it needs a root before its sprouts
a shoot. Seeds contain food supplies that support initial growth but leaves quickly form once the shoot
has broken out of the ground. In some cases the food stores themselves are drawn above ground and
become the first ‘seed leaves’.
All this can happen in the dark, thanks to that vital food store but seeds need water and warmth to
germinate otherwise they may remain dormant for months or even years. There are records of date
seeds from the time of King Herod two thousand years ago that have germinated into viable plants.
Leaves don’t do anything. The leaf is the plant’s food factory. It is here that the almost magical
process takes place that turns the equivalent of fizzy water (water and carbon dioxide – and a few
mineral salts) into the plant’s food and structure, including wood. Photosynthesis harnesses light energy
from the sun, using a green pigment called chlorophyll, combining water from the soil and carbon
dioxide from the air to make first sugars and then starch and other more complex chemicals.
Most living leaves are green – or at least the ones that contain chlorophyll. However, there are other
pigments – ie, carotenoids, anthocyanins and betalains, which can mask the colour and the chlorophyll
degrades and is lost in the dying red, brown and yellow autumn leaves.
Leaves need to be exposed to the sun’s light and this accounts for their patterns on trees and other
green plants. They may be paired, or grouped, or spiral up the stem following mathematical laws, but
they need maximum exposure to contribute to the life of the plant. Look up from under a broad-leafed
tree and you will see how the canopy cuts out virtually all the light.
4
2.0 Plants and the curriculum
In the National Curriculum for Science for England, plants have their own strand throughout. At Key
Stage 1 the curriculum looks at the conditions (including light and water) that green plants need to
grow, the names of parts of their structure (leaf, flower, stem and root) and an understanding that seeds
grow into flowering plants. Schools using the QCA Scheme of Work can teach this largely through
Unit 1B – Growing plants and also Unit 2B – Plants and animals in the local environment.
At Key Stage 2 students learn about the effect of light, air, water and temperature on plant growth –
inviting some simple scientific investigations. They are taught about the role of the leaf as the plant’s
‘food factory’ and how the root both anchors the plant and takes in water and small amounts of mineral
salts, which are transported by the stem to other parts of the plant. They learn about the parts of the
flower (stigma, stamen, petal and sepal) and their role in a plant’s life cycle – including pollination, seed
formation, seed dispersal and germination.
2.1 Science in the National Curriculum for Wales
Interdependence of organisms
At Key Stage 2 students should use and develop their skills, knowledge and understanding by
investigating how animals and plants are independent yet rely on each other for survival. They should
be given opportunities to study, through fieldwork, the plants and animals found in two contrasting local
environments – eg, identification, nutrition, life cycles and place in the environment.
2.2 Science and Technology in the National Curriculum for Northern
Ireland
Animals and plants
At Key Stage 1 students should be given opportunities to find out about the variety of animal and plant
life both through direct observations and by using secondary sources – eg, drawing and naming living
things seen on the way to school, in and around school or on a school visit. This helps students to sort
living things into the two broad groups of animals and plants, and to recognise and name the main parts
of flowering plants including root, stem, leaf and flower.
At Key Stage 2 students should be given opportunities to observe similarities and differences among
animals and among plants, find out ways in which animal and plant behaviour is influenced by seasonal
changes – eg, find out about some trees losing their leaves in autumn, buds opening in spring or
hibernation and migration in winter. Students can also investigate local habitats, including the
relationship between the animals and the plants found there, and develop skills in classifying animals
and plants by observing external features. They can also investigate the conditions necessary for
growing familiar plants including light, heat and water, and learn about the life cycle of flowering plants
– including how pollen is taken from the stamen into the stigma, fertilised in the ovule and a seed is
produced which is dispersed in a variety of ways.
5
3.0 Caring for plants
There are some basic rules for looking after plants. When placing plants in windows, remember:
Summer, east or west;
Winter, south.
Care for classroom plants can sometimes be inconsistent, from over-watering to neglect in long
holidays. Modern schools may have large windows that are often both warm and light. South-facing
windowsills may be too warm and sunny for plants in summer – though ideal in winter. East and west
windows are the best places for plants in summer.
If the compost in a pot feels moist the plant does not need watering. Little and often is a recipe for
disaster. When plants need watering, water them well and then leave them until the compost is getting
dry. Over long holidays put the plants in a trough filled with absorbent stones (Hortag stones), which
retain the water. Plants left standing in water run the risk of rotting. Capillary matting or self-watering
systems are available from garden centres. Move plants out windows where they may get too hot in
summer, or too cold in winter. Or you can take the plants home. Always plan for long holidays.
Liquid fertilisers are best for indoor plants and there is a wide range of proprietary brands. Remember
to follow the instructions carefully.
Plants that are infected by pests of one sort or another should be removed. Insect pests can be
reduced or even prevented by using insecticides, but using these insecticides may increase the risk of
harming your students. Phostrogen plant pins are available in garden centres and shops. Push them
into the compost and the insecticide spreads to the plant, making it poisonous to insects. The pins taste
bitter to discourage chewing, but you should still keep them in a safe place. Choose a safe insecticide
and keep it away from your students.
Transfer plants that outgrow their pots. Replace failing plants and maintain a healthy and attractive
display. Classrooms are not the ideal place for many plants. They can be too warm at times and vary
widely in temperature, so choose your plants carefully.
3.1 Safety code for classroom and other plants

Teach children to avoid touching their eyes when handling plants.

Teach children never to taste any part of a plant unless they are absolutely certain that it is
safe to do so.

Warn children not to eat attractive looking fruits and seeds.

Use seeds that have not been treated with pesticides or fungicides.

Teach children to always wash their hands after handling plants.
6
4.0 An alphabetical list of suitable classroom plants
Broad beans. These are large, easy to handle and cheap to buy in bulk. Avoid handling beans that
have been treated to prevent fungal growth. Soaking the beans overnight softens the seed coat and
also speeds germination.
Water or bubbles comes from a tiny hole in a soaked bean seed when you squeeze it. This is the hole
the pollen enters to fertilise the immature seed. Rub the softened seed coat between your finger and
thumb to break it. You can see the first root, which sits in a pocket in the seed coat. If you split the two
halves of the seed with a thumbnail you can see the young plant – root, shoot and leaves. The two
cotyledons – the bulk of the bean – are the food stores for this young plant.
Broad bean shoots respond to light and gravity very well. A broad bean plant germinated in a closed
box will grow through a small hole made in one side to reach the light. If you lie a broad bean plant pot
on one side the shoot grows upright. Stand the pot up and the stem changes direction and grows up
again.
Bromeliads. These are house plants with attractive foliage that do not need a lot of attention. Those
most familiar to children are pineapples, but there are many others. They make a good link to early
South American societies, as Incas, Mayans and Aztecs all used them for food and for fibres.
Bryophyllum daigremontianum and B tubiform. These are two windowsill plants that are sometimes
called ‘resurrection plants’. They both grow quickly to a height of around 60 cm if regularly watered and
fed. They produce tiny plantlets on the edge (daigremontianum) or end (tubiform) of their leaves. The
plantlets drop off to root themselves and grow into new plants. Both plants are tough and can survive
some neglect, but do need re-potting as they grow.
Busy lizzy. All the varieties grow well on sunny windowsills if watered and fed. This small plant grows
well in shade and semi-shade too and flowers profusely. Stem cuttings root in water or in soil and the
pollinated flowers produce exploding seed heads. The flowers are claimed to be ‘self-cleaning’ and the
exploding seed pods show a good example of seed distribution very well. There is a tall, wild form of
the species called ‘Policeman’s Helmet’.
You can see water moving through a plant. Busy lizzy plants have translucent stems, so coloured water
– use dilute ink or water in which water-based felt pens have been soaked – can be seen being carried
up to the leaves.
7
Cacti. The spines can be painful, especially the barbed ones, which are difficult to remove. If brushed
against, whole branches can break off and stick into skin. These can be removed by putting a pocket
comb between the cactus and the skin and flipping sharply upward into an empty space. If you have to
handle cacti, use a folded cloth to circle the plant.
Cacti need bright sun and very little water – especially in the winter. They can flower vigorously,
contrary to the belief that they only flower every seventh year. Some produce numerous baby plants
round the base and these can be detached and potted.
Chlorophytum or spider plant. This is a tough plant that can survive some neglect. Plantlets,
complete with roots, grow on trailing stems and can be removed and potted.
Coleus. A good classroom plant, providing it has plenty of light and is not allowed to go short of water.
The leaves are multi-coloured but the flowers are insignificant. The flowering shoots should be removed
to maintain the large coloured leaves.
Cress. Cress may be familiar to you, but it can still be novel to your students. Its great quality is that it
can be grown for eating without needing soil. The seeds are sticky so they can be stuck to any wet
surface. They grow on paper towels or pieces of cloth, or dip a ball of wet cotton wool in cress seeds
and then suspend it in a jar to keep it damp. You can grow a green ball of cress in four or five days.
Duckweed. These small pond plants can be grown easily in saucers or plastic petri dishes on
windowsills. You can also try growing them in pond water, rainwater, tap water, distilled water and very
dilute fertiliser solution. Count the fronds. Where do the plants grow best?
Geraniums. These are tough plants that can withstand baking on sunny windowsills. Cuttings can be
taken or side shoots can be snapped off and rooted in soil or water.
Ginkgo (Maidenhair fern). This is an unusual plant that needs to be grown outside as it increases in
height. This tree was alive in the time of the dinosaurs. There are claims that the leaves have medicinal
properties, but they should not be eaten.
Mung beans. Mung, masoor and urd beans are common pulses and important food sources in southeast Asia. Their history and use is mapped on the Kew Gardens plant culture site:
www.plantcultures.org/themes/food_beans.html.
These can be grown in warm, dark places and produce the bean sprouts used in Chinese cooking. You
can buy them from supermarkets or health food shops. Soak a handful, allow the beans to drain and
put them in a jar. Cover the top with a cloth secured by an elastic band and put the jar in an airing
cupboard or warm dark place. Add water to the jar daily, rinse well at least twice and drain-off the
excess. The long roots that are produced are edible. However, if you leave the germinating seeds the
seed coats are pushed off and the leaves sprout. If you leave the seeds in the dark the shoots will be
yellow – as used in Chinese cooking. If you put them in the light they produce green leaves. To remove
the discarded seed coats, fill the jar with water and the seed coats will float to the top.
Mung beans grow into an edible salad vegetable in hygienic conditions. They show the effects of
growing in light or darkness or using colour filters under coloured light. It is easy to measure and record
the root growth.
8
Persian violet. The Persian violet (Exacum affine) is native to Yemen. This plant has small flowers and
is a good plant for growing in shade. It can be grown in the winter and summer. During the warm
summer days it flowers very quickly.
Philodendron. There are a thousand or more species of these arum flowers. They are a popular group
of plants that are grown for their ornamental foliage. Indoor plants thrive in warm temperatures and can
survive at lower light than other house plants. Wiping the leaves with water removes any dust and
insects. Plants in pots with good roots systems benefit from having a weak fertiliser solution applied
every few weeks.
Piggyback plants. Tolmea is a plant that produces baby plants at the junction of the leaf stalk. If these
are not removed more plantlets grow on the leaves of the first plantlet. Plantlets can be grown in potting
compost.
Sensitive plant. Mimosa pudica grows well in a moist atmosphere – so it’s wise to bring the plants in
only to demonstrate the folding of the leaves in response to a stimulus.
Cut the base from a two litre soft drinks bottle and put it over the plants until the leaves are spread.
Then remove the bottle and blow on the plant gently. The leaves respond by folding and dropping
down. They recover quickly for further demonstrations. The folding is due to a rapid loss of pressure in
cells close to the leaf base. Sensitive plants can be grown from seed.
Spiderwort. Tradescantia plants grow well on windowsills and benefit from regular watering and
feeding, and are also fairly resistant to neglect. After a year the plants lose their healthy appearance. If
you make cuttings they grow well in water and produce roots. This plant’s main scientific interest is as
an indicator of harmful radiation, which changes the colour of its stamens from blue to pink – not a
primary science activity!
Umbrella plant. Umbrella plants or Nile grass are one of the few plants that tolerate over-watering. The
plants can withstand bright sunlight but should be kept standing in a bowl of water. The flowering
umbrellas root if they are planted with 3 cm of their stem resting the umbrella on the soil, or placing the
umbrella upside-down in a shallow dish of water.
9
5.0 Poisonous plants
It is safest to treat all plants as poisonous unless you have knowledge to the contrary. Parts of some
plants – rhubarb leaves, tomato plants except for the fruits – are partly poisonous. Remember too that
some children – those with asthma and allergies – may be especially vulnerable.
This list is not comprehensive. All parts of the listed plants are poisonous, except where noted.
Garden and hedgerow plants
Black bryony
Ivy berries
Black nightshade – especially unripe berries
Larkspur leaves and seeds
Bluebell
Lily of the Valley
Bracken
Lupin
Buttercup
Mistletoe leaves and berries
Christmas rose
Monkshood or aconite
Cuckoo-pint
Potato – except the tubers
Daffodil – all, especially bulbs
Ragwort
Deadly nightshade
Rhubarb – except leaf stalks
Foxglove
Snowdrop – all, especially bulbs
Giant hogweed
Tomato – except fruits
Hemlock
Tulip bulbs
Henbane
White bryony
Iris and ‘flags’, all but especially rhizomes
Woody nightshade – all, especially berries
Castor oil plant seeds
Dumb cane
House plants
Hyacinth bulbs
Poinsettia leaves and flowers
Trees and shrubs
Broom seeds
Privet – all, especially berries
Cherry laurel leaves and fruits
Rhododendron leaves and flowers
Holly berries
Snowberry fruits
Horse chestnut leaves, flowers and ‘conkers’
Spindle tree
Laburnum – all, especially seeds
Yew – all, especially seeds
Vegetables and fruit
Beans – French and red kidney, raw or undercooked Rhubarb – leaves
Potato – all green parts, including tubers
Tomato – leaves
Tomato and bean seeds, and seed potatoes have been offered to schools as part of the Year of Food
and Farming. Parts of these plants contain toxins. See over for further advice on care with them.
Tomato and potato plants are members of the Solanaceae family and contain toxic glycoalkaloids –
although the concentration is low in tomato fruits and cooked potato tubers. Quite large quantities of
inedible parts of the plants or raw potatoes need to be eaten to cause more than mild gastrointestinal
problems. Bean seeds – and some varieties of peas – contain variable quantities of toxic lectins and
other harmful substances. These can be inactivated by soaking and cooking.
Children should be told not to eat these parts of the plants, including raw potatoes or beans and it is
wise not to let young children handle seeds as they may eat them and choke or become ill. Gloves may
be useful for people with sensitive skin.
So keep planting. It’s great for children to see their food growing!
Information on growing potatoes can be found at: www.potatoesforschools.org.uk.
10
6.0 Activities with plants
Plants compare poorly with active animals for interesting children, but there are a number of activities
that can make plants more engaging. Some of these demonstrate plant movements and others involve
growing plants for food.
Plants ‘do’ a lot, but this may not be apparent to children. There are a number of simple studies that,
among other things, produce relatively quick result.
Do all seeds absorb water? Some seed coats – eg, the dark coats of sweet pea seeds and the coats
of nasturtium seeds – are waterproof. To start them germinating, an adult can cut away a small piece of
the coat before putting them in water. Take great – the coats are hard and slippery. Seeds that
germinate in nature need soil with a high moisture content.
How much water do seeds take up? Put mung bean seeds in a measured amount of water and
observe how much is absorbed. You can also weigh the seeds before and after; or both.
How does water travel through a plant? The familiar stems-in-coloured-water activity is still a thrill for
children. Try celery stalks in dilute ink and after an hour or two cut the stems to see how far the ink has
travelled. You can colour white carnations in the same way, or split the stems and put the ends in two
different colours for a multi-coloured bloom.
11
Where does the water go? You can demonstrate transpiration – the loss of water from a plant – by
putting a plastic bag over a potted plant and sealing it to the pot with an elastic band. Strictly you should
cover the soil surface to prevent losing water from there. Water condenses and accumulates on the
inside of the bag. It has been drawn through the plant and lost from the leaves. Transpiration also helps
to cool plants on hot days.
Do plants need light to grow? Seeds do germinate in the dark (as they must if they are underground)
and the plants grow at first using the seed food store. Green plants need light to manufacture food so
plants grow long and straggly in the dark – a process called etiolation – in an effort to reach the light.
There is a lack of chlorophyll, needed for photosynthesis and etiolated plants are yellow and unhealthy.
Given light, plants regain their green colour and thrive.
Do plants grow differently in different coloured light? Cut the bases from plastic soft drinks bottles
of different colours and stand them over growing plants – cress is ideal. Compare the differences in the
growing plants.
Do plants grow towards the light? Grow cress on a damp cloth or paper towel on a sunny windowsill.
The plants bend towards the window, spreading their leaves to catch as much sunlight as possible.
Now put a ‘mirror’ made from cooking foil behind the bending plants – the opposite side from the
window. This balances the light and the cress grows straight upward again.
Can plants find the light? Grow a plant in a box – keeping it watered – with a small hole through
which the light can enter. The plant etiolates, but will eventually emerge from the hole.
Does coloured light make a difference? It is easy to investigate the effect of light on mung beans. Try
putting a jar in daylight and another in the dark, or under a coloured gel to filter the light. You can study
growth, water absorption and temperature effects.
12
Does fertiliser affect plant growth? Grow two similar plants, one with and one without fertiliser.
Children may suggest that other growing media – milk, cola – will enhance plant growth and these are
worth trying, although the results may not be easy to explain.
How do plants break paving stones? Soak some broad bean seeds and plant them in compost in
small containers. Cover the compost surface with a centimetre layer of liquid plaster of Paris and let it
harden. The beans grow to push their way through the plaster. Small plants like beans cannot break
paving stones, but larger woody plants can.
Do flowers move? Daisy flowers close at night and open in the daytime. Daisies are composite flowers
– the flower heads are a mass of smaller flowers. You can show this with two clumps of daisies – one in
water on a windowsill and the other in a cupboard. Observe the differences then swap them over.
This movement is called nyctinasty and there is no clear explanation for it. Charles Darwin suggested
that folding the petals, and the leaves of some beans, helped prevent cold and possibly frost damage.
Another scientist called Bunning suggested that some plants were sensitive to moonlight and this
confused their measurement of day length. (A full Moon might be recognised as a false day). Some
forest floor plants can be overwhelmed by bright sunlight and close their sensitive leaves 10 seconds
after exposure to the sun. This is an area where your students might make a new discovery!
There are more ideas at: www-saps.plantsci.cam.ac.uk/docs/p4pp/lp/lpE.pdf.
6.1 Some twists on growing plants
Growing potatoes in a bucket. Children who enjoy crisps and chips will be surprised to find out how
easily these potatoes grow. Early in the spring term put some seed potatoes – not strictly ‘seeds’ but
root tubers – on an egg tray with the sprouting end pointing up. Leave them under a table at room
temperature to sprout. In four or five weeks the sprouts will be 2 cm long, ready for planting.
Put some crocks or gravel in a container to help drainage and nearly fill it with moist compost. Put one
potato in the container with the sprouts pointing up and cover the potato with 2 to 3 cm of compost.
Keep the container indoors or put it in a sheltered frost-free place outside. Keep the compost damp and
cover the potato if any underground part is exposed. Potatoes should have formed 12 to 14 weeks after
planting. Lift the plants carefully and have a look. Pick off the largest potatoes and then replace the
plants in the soil so that they can continue growing. You can also cut the sprouting top off a potato and
plant it so that the top of the tuber is just showing. Remember that all parts of potato plants except the
tubers are poisonous. Green tubers are also poisonous.
Watching seeds growing. Avocado stones and other large seeds can be grown in moist peat. If they
start to produce roots they can be potted up and grown.
Bulbs and large seeds can be rooted in water. Push three cocktail sticks into the sides of a bulb or seed
to support it and stand it over a jar of water, with the sticks resting on the jar rim. Onions and garlic
grow well this way. Avocado seeds take a long time to start. Other suitable seeds include oranges,
lemons and peanuts.
Growing plants without soil. This activity refutes ideas that plants are somehow ‘made from soil’.
Most seeds contain enough nutrients to produce quite large plants if supplied with water only, but you
can get greater growth by growing seeds in a half-strength solution of a houseplant food.
There are detailed instructions at:
www.phostrogen.co.uk/gardenerscorner/guides/ (download the hydroponics guide).
You can grow plants in jars of a hydroponic solution, in absorbent stones wet with solution, or on
capillary matting kept wet with the solution. Nutrient solutions in jars need replacing regularly – probably
weekly. If the solution level falls during the week, replace with clean water, not more solution, as the
plants absorb more water than minerals.
Growing an identical plant in parallel to the hydroponic solution plant, but in pure water, shows the
importance of mineral salts for healthy, vigorous growth.
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Fluid sowing. Seeds suspended in cold water paste stick to moist surfaces. Germinate cress, mustard
or lettuce seeds on paper towels then wash them off into mixed school paste and stir. Put the mix in a
plastic bag, cut-off one corner and use the bag to sow the seeds – on vertical surfaces, or to write
letters or words.
Plant ‘hair’. Put wet cotton wool in an eggshell and draw a face on the outside. Shake on some cress
seeds and your egg head soon grows green ‘hair’. Sprinkle seeds on wet unglazed pottery, plaster of
Paris or a house brick. You can also write letters or words in seeds.
Root cuttings. Tradescantia and busy lizzy both root well from cuttings to produce new plants. Make
cuttings using a very sharp knife or razor. This is a teacher demonstration rather than a student activity.
First, identify a node – the point where the leaves are attached to the stem. Then cut short lengths
(about 10 cm long) from the plant just below the node. Push the length into potting compost or place in
water, first removing any leaves that might be underground or underwater.
Tradescantia, busy lizzy, geraniums and coleus all root well in water. When the cuttings have rooted,
they can be transferred to potting compost. Some science suppliers sell transparent jelly for rooting
cuttings. The roots are clearly visible as the cuttings grow. You shouldn’t need rooting hormones for this
activity. However, if you do use rooting hormones lock them away when you are not using them.
Bottle gardens. Glass containers have obvious disadvantages, but large plastic bottles – especially
sweet jars with their wide apertures – are ideal for the task and can be planted upright or stood on their
side. Bottle gardens demonstrate a small water cycle – water transpires from the leaves, condenses
and runs back into the soil. Small slow growing plants, including ferns and mosses are best planted in a
few centimetres of compost. Bottle gardens should get plenty of light, but not direct sunlight.
Exploring stinging nettles. Stinging nettles are not suitable classroom plants. However, many animals
are not troubled by the stinging hairs on nettles and feed on the plants. A surprising number of these
animals can be recovered by putting the stems of nettles inside plastic bags and shaking them. You
might find aphids, plant sucking bugs, ladybirds and ichneumon flies, along with caterpillars in season.
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Carnivorous plants. Plants like Sundew and Venus fly traps and the many pitcher plants originate in
soil that is low in nutrients. As a result, they have evolved the ability to catch and digest flies as a
source of mineral salts. Children have a macabre interest in carnivorous plants which can be bought
quite cheaply at garden centres and flourish in the right conditions.
The plants are supplied with growing instructions, but exposing them to the summer sun and heavy
watering with rainwater is usually successful. However, move them out of direct sunlight in winter. Do
not use tap water and, of course, do not give them fertiliser.
The Sundew and Venus fly trap snap shut very quickly in response to stimulus – trigger hairs on the
leaf initiate the leaf’s response. Frequent stimulus leads to a slower response time. Pitcher plants offer
insects a slide to destruction. The plants’ funnels have covers, but these do not close; presumably they
simply hinder escape. Charles Darwin investigated carnivorous plants, finding that they responded to
complex stimuli – but not to falling rain. They will close over dead insects, so your students can ‘feed’
them. Do point out that most plants do not ‘eat’ in this way – and like any green plant, they cannot
survive without photosynthesising.
Discovering dandelions. These plants are abundant, persistent, fast growing and are ideal for
investigations. The QCA Scheme of Work for Science for England, Unit (5/6H), introduces the skill of
sampling a population by counting dandelions.
Dandelions are hugely successful plants. They have found an environmental niche and filled it. They
are best suited to ‘disturbed habitats’ and grow in lawns and gardens because their tiny, wind-borne
seeds can lodge in the cracks in broken ground. They grow vigorously with their shape adapting to welltrodden paths and to sheltered corners. They spread flat on paths, or grow up towards the light when
they are rooted in the shade. Their long taproot can draw water from below the dry topsoil in a drought,
keeping them green when all around is brown grass.
Investigating how dandelions grow. Are flat and upright dandelions different plants? One way to find
out is to swap them. Put a food tin, with both ends removed and no sharp edges, round a flat plant.
Tread down on it and lift a core of soil and most of the dandelion. Do the same with a tall dandelion
growing in the shade. Exchange the plants, watering them in. The different conditions quickly lead to
changes in the shapes of each plant, which can be related to their need for light. The plant in the shade
grows up towards light while the plant in the centre of the field spreads to catch the bright sunlight.
Dandelions as a medicine and in history. Today, dandelions are considered to be invasive,
persistent, deep-rooted weeds. But not so long ago they were valued plants – respected for their
nutritional and medicinal qualities. Their Latin name, Taraxacum officinale, derives from the Greek
words for illness or disorder taraxots and remedy or medicine akos and officinale, of the herb markets.
Dandelions or Dent-de-lion (‘lion’s tooth’ in Old French) with their jagged leaves were first recognised
as a medicine by the ancient Greeks. In the Middle ages the diuretic root was used to treat kidney and
liver disorders. An 11th century Arabian medical text, Avicenna’s Herbal, is the first written record of
their medicinal properties. Dandelions spread to America with the first settlers where the Cree tribe then
used them to treat jaundice, eczema and anaemia.
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7.0 Classroom resources
7.1 Models of plants and flowers
Biologically accurate models are available that, for example, illustrate flower structure, pollination and
fertilisation. Expect to pay upwards of £60 for this these types of models. More primary-friendly are felt
illustrations of plants and flowers that students can assemble. These are often supplied in parts with
Velcro connectors and Velcro-backed labels. These maybe supplied with a backing sheet that doubles
as a storage pocket. Prices vary, with small models ranging from £20 and more complex models
around £40.
Several suppliers offer a large felt flower with a bee for pollination explanations at around £40. Philip
Harris also supplies a glove puppet bee that can be used to transport ‘pollen’.
Economatics offers a large floor foam puzzle with the five main parts of a plant for around £20.
Scientific and Chemical is one supplier that has a Tree for all seasons for around £30 that can be used
to illustrate the annual changes in a tree and a set of magnetic illustrations of plant life cycles for £20.
7.2 Picture and poster packs
There are plenty of these available, although some are illustrated and labelled in unnecessary detail.
You should be careful when choosing the appropriate resource. It may have the complete anatomy and
biology of a plant, but do you need this? You may prefer a resource with simple, clear illustrations that
doesn’t attempt to cover too much. Prices vary from £3–£4 for a poster to £20 or more for a picture
pack.
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7.3 Cultivation in the classroom
Look for ‘fast plants’. Brassica rapa is a type of cabbage plant that can complete its life cycle from seed
to seed in five weeks in constant light. It completes its life cycle fairly quickly on a windowsill, but for the
fastest results you need to light the plant for 24 hours a day.
The light is normally provided by a light bank, which can be quite expensive. However, you can make
your own light bank and many fast plant packs contain instructions. Home-made light banks must be
electrically tested before they are used in classrooms. Lights in schools at night can lead to calls for the
police – especially if they switch on and off intermittently, as some light banks do. Ideally, set one up in
a room or cupboard without outside windows.
Middlesex University Teaching Resources and Plants in Primary Science are sources of complete, but
expensive, light banks. Complete instructions for building your own are available at
www.fastplants.org/grow.lighting.light_bank.php. Home-made light banks must be electrically tested by
a qualified electrician.
Many salad plants – rocket, basil and lettuce – can be cultivated in weeks from seed and eaten. But
remember that they have not completed their life cycles – they will not have flowered and seeded.
Seeds from science suppliers should not have been treated with fungicide and so can be handled
safely.
You can grow cress, mustard and mung beans all year round. They sprout quickly and, if you keep
them in hygienic conditions, you can eat them. They may not be novel to you but your students will still
be excited by these old favourites.
Timstar offers bulk packs of broad bean, cress, pea and sunflower seeds. Scientific and Chemical
supplies broad beans, peas, maize, wheat, mustard, barley, oats and mung beans without fungicide
dressing in 500 g bulk jars.
Garden centres have a huge range of plants – including engaging ones like carnivorous plants. You will
have to follow cultivation advice carefully for these carnivorous plants. For example, Venus flytraps,
must be given only rainwater and suffer if their traps are continually sprung.
Growing plants in transparent containers of gel allows students to see plants’ roots and helps them to
understand that plants do not draw all that they need from soil. Root windows and flat-sided observation
tanks are intended to hold soil, but the roots grow against the sides of the tank, so that they can be
seen easily.
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Outdoors, grow beds and grow bags can contain and promote plant growth. It is worth comparing plant
pots and tray prices with local garden centres. Miniature greenhouses and propagators can help
accelerate plant growth, but are quite expensive. You can achieve similar effects with a two litre soft
drinks bottle. Cut off the base and put the bottle over the growing plant. Removing the bottle top
reduces misting.
Many suppliers offer compost and you can compare this with garden centres for prices and
convenience. Compost should be peat-free, dry and clean to use. You can mix it with dry soil, but do
not grow pot plants in ordinary soil.
7.4 Garden tools
Child size garden tools are manageable and in proportion for students, although of course they are not
heavy-duty. Expect to pay upwards of £25 for a set of six. Small hand tools are also better suited to
children’s hands.
Small barrows can be useful and TTS offers a fabric ‘folding wheel barrow’ for around £33. The barrow
lies on the ground for filling and can then be wheeled like a traditional barrow. Don’t forget small sized
gardening gloves, which are essential when children are handling soil.
7.5 Root propagation gel
If you plan to take and grow cuttings from some of your classroom plants, this clear gel, commonly
provided as a ‘six-pack’ of yoghurt pot-sized containers, enables you to show the roots sprout from the
cutting. The gel is also available as water storage granules.
7.6 Root windows / observation tanks
Clear-sided growing troughs are good for showing root systems and these are normally provided with
watering systems. You can get the same effect from growing plants in plastic aquaria – or even in cutoff soft drinks bottles.
7.7 Miniature greenhouses
There are a variety of windowsill greenhouses available – they keep plants warmer but water
evaporates from the soil quickly and in south-facing windows they may be too warm. You can make
your own small greenhouse by turning a plastic aquarium upside-down over growing plants or covering
individual plants with the base cut from a two litre soft drinks bottle.
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8.0 Resources
8.1 Primary plants
Primary plants, Martin Braund, 2001 (ISBN 9781841900384) is published by Continuum Books at
£29.99.
This book is fully illustrated and includes a CD-ROM with many beautifully photographed images of
plants and flowers. This is a versatile resource for whole-class teaching and students’ own topic work.
Contents: Introduction; 1. Our world of plants; 2. Variety is the spice of plant life; 3. Carry on growing;
4. Feeding the world; 5. Water: a question of balance; 6. Carrying on; 7. Plants and the environment;
8. Mighty microbes; 9. Celebrating with plants; 10. Progressive planting; 11. Resources;
Concept Summary.
An excellent guide to activities with plants in schools.
www.continuumbooks.com
8.2 Growing Schools
The Growing Schools website has been designed to support teachers in using the ‘outdoor classroom’
as a resource across the curriculum for students of all ages. It contains a great deal of useful
information and has links to other relevant resources: www.growingschools.org.uk. Information on seed
offers is available at www.schoolsorganic.net.
8.3 Get your hands dirty
This folder from the Department for Children, Schools and Families (DCSF) is aimed at secondary
schools, but contains valuable advice if you plan to get more ambitious with plants (and animals). It has
sections on container gardening for schools without useable land and advice on school gardens,
composting and small ponds. If you have a greenhouse you will find help with both unheated and
heated cultivation.
Files are available from:
DCSF Publications
PO Box 5050
Sherwood Park
Annesley
Nottingham
NG15 0DJ
File and updates are available online at: www.growingschools.org.uk.
8.4 The Biotechnology and Biological Research Council (BBSRC)
All of the following resources for primary students are available from the BBSRC website. Several will
extend your students’ understanding of green plants. Some are aimed at primary but touch on
secondary school concepts and some illustrate secondary school style equipment – eg, petri dishes
and test-tubes. These resources are well suited to extending more able students and to science clubs.
www.bbsrc.ac.uk/society/schools/primary/.
DNA in the garden is set of four worksheets suitable for Key Stage 2 students (ages 8–11). The
worksheets are used to explore the science and surprises behind plant DNA. What it is, how it works
and how we put it to use.
How the mushroom got its spots is aimed at anyone who wants to delve into the fascinating world of
mushrooms, toadstools, moulds and other fungi. This booklet and worksheet contains useful Key Stage
links throughout.
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Build your own cell is an extension ‘cut and paste’ activity introducing plant and animal cells for 10–11
year olds and is also curriculum relevant for 12–13 year olds.
Easy PEAsy seed germination is a germination and variables activity for 8–11 year olds.
Stings and things is an extension investigation into pH for 10–11 year olds and is curriculum relevant for
12–13 year olds.
Photosynthesis explored is a fact sheet and investigation for 10–13 years.
Seeds and plant growth discovery pack is designed to allow students aged 5 –12 to explore the world of
seeds and plant growth. All the activities can be used to encourage children to care for and appreciate
living things, and to think about the world around them. The activities can also be used to encourage
children to think about health and safety issues.
The plant detective is an interactive presentation suitable for 8-11 year olds, describing the different
parts of plants. The plant detective covers topics such as reproduction, photosynthesis and adaptation.
To use The plant detective you need to have a Flash Viewer installed on your computer. Alternatively
you can view a text only version.
If you would like further information about any of these resources contact BBSRC at
Schools@bbsrc.org.uk.
8.5 Learning through landscapes
www.ltl.org.uk
Primary resources include:
Science in the school grounds by Jill Thomas ISBN 1- 85741-085-8
Gardening with children is a Royal Horticultural Society (RHS) resource in collaboration with the BBC:
www.bbc.co.uk/gardening/gardening_with_children/
The RHS offers free school membership of their web-based Campaign for School Gardening at:
www.rhs.org.uk/schoolgardening/.
8.6 The AstraZeneca Science Teaching Trust
www.azteachscience.co.uk/code/development/lets_talk/contact_information.htm
Let’s talk! has been developed to encourage discussion of science issues in both primary and
secondary schools. It has been trialled in125 Scottish schools and includes topics like:
Plants matter – habitat destruction and the importance of plants in food and medicine.
Environmental issues – pollution, global warming, world health and poverty.
Human reproduction – test-tube babies and designer babies.
For information on how to obtain the materials, contact Marjorie Smith at:
Lets.talk@btinternet.com.
8.7 The Royal Botanic Gardens, Kew
www.kew.org/education/ offers school gardening and wildlife area advice, including a downloadable
wildlife resource: www.kew.org/education/wildlifezone/.
Schools can also book sleepovers at Kew.
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8.8 The Field Studies Council (FSC)
In addition to field courses and INSET, there are a number of primary publications listed at:
www.field-studies-council.org/publications/bycategory/primary.aspx
Note especially their publications in collaboration with Science and Plants for Schools (SAPS) – also
available as downloads from: www-saps.plantsci.cam.ac.uk/primintro.htm
Science and Plants for Schools has recently refocused on secondary schools and moved from
Homerton College to Cambridge University Botanic Garden. Many of its excellent publications are
available online, or as paper resources from the FSC. The 36 page booklets cost £3 each (2008 prices)
from the FSC and are slightly more expensive from some science suppliers, so this can be weighed
against the cost of downloading and printing.
The booklets in the series Plants for primary pupils provide a comprehensive range of activities and aim
to cover work that must be done with plants as part of the primary curriculum in England, Wales,
Northern Ireland and Scotland. (Booklets 1, 2 and 3 have been published and are also available on the
website; booklets 4 and 5 were published during 2008.
Many activities emphasise growing plants in classrooms or outside – eg, in tubs in a schoolyard or in a
school garden. This lets students make first-hand observations, often on their own plants, and become
familiar with plants and how they grow. There are games that reinforce their learning and simple
investigations that help them find out more about how plants work.
You can still contact SAPS direct at: saps@homerton.cam.ac.uk.
From September 2008 they have reduced the number of workshops for the primary and lower
secondary sectors.
8.9 Gatekeeper guides
www.gatekeeperel.co.uk/guides.html
Lyn Merrick illustrates and publishes Gatekeeper guides. These resources are beautiful laminated
cards with keys to wildflowers and native animals. They are available direct from her, with discounts for
quantity, or from the Association for Science Education (ASE), with members’ discount.
www.ase.org.uk/htm/book_store/
See also Gatekeeper’s ‘Plants UK’ identification CD-ROM.
8.10 Teachers TV
The Blue Dragon – a cartoon science series for Key Stage 1 students – includes a programme on
plants: www.teachers.tv/video/1776.
The Blue Dragon follows the story of four real animals and a dragon that embark on a journey. Through
their experiences the animals learn about science in the world. The programme explores:
 plants as living things;
 different parts of a plant;
 different parts of vegetable and fruit plants – the roots, shoots, stem, flowers and fruit;
 the idea that some plants can be dangerous and should not be eaten;
 how seeds can grow into plants;
 how different seeds grow into different plants and why plants need air, water and light to grow.
8.11 4Learning
Seeing science – Plants is one of nine CD-ROMs in the Key Stage 2 Seeing Science series, with video
clips and activities. The subject areas covered are What are Plants?, Growth and Nutrition,
Plants Provide and Life Cycles. A site licence is available for around £10.
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9.0 Beekeeping
The British Beekeepers Association (BBKA) has developed a schools pack for Key Stages 1 and 2,
which is a useful tool in teaching about the plants and animals that surround us, including minibeasts,
pollination and care for the environment. It is available in two forms – as a conventional ring binder or
as a CD-ROM. The file has 90 pages with both line drawings and colour photographs and was revised
in 2008. It is full of lesson ideas and the worksheets – if used selectively – are appropriate for Key
Stage 1 and 2 students. The pack costs £15 including postage and packing, from the BBKA.
The CD-Rom version is structured as a self-contained website so you don’t need an internet
connection. It has two sections – the teacher-supporting staff room and the interactive classroom.
Children can browse this safely, learning by exploring. The CD-ROM costs £10. More about this
resource and order forms for both products are available at www.britishbee.org.uk/bees4kids/.
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