What is compost?
Talk to your pupils about what happens to food—particularly fruit and vegetables—when it starts to rot. Discuss the fact that microorganisms (bacteria and fungi), as well as insects and worms, feed on food waste and break it down (decompose) it. This can then be used to add nutri- ents (‘goodness’) to soil, which in turn helps new plants to grow.
Provide your pupils with samples of compost and soil in white plastic trays. They can describe and compare the two types of material, refer- ring to aspects such as the colour, texture and composition. They can then use magnifying glasses, pooters and glass jars to collect, observe, identify and make labelled sketches of the invertebrates in each sample.
What to compost
Good compost should contain equal amounts of ‘green’ (e.g. grass clip- pings, fruit and vegetable peelings) and ‘brown’ waste (e.g. dry leaves, twigs, cardboard and paper). Other compostable waste your school may generate includes tea bags, cotton or wool clothing and eggshells.
What NOT to compost
Avoid non-biodegradable items such as glossy material, synthetic fabric and woody plant material. Diary products, cooked food or meat should never be added to a compost heap/bin because they can attract rats and flies, Also don’t add any diseased plant material, as that can spread the disease to new plants.
Compost will eventually be created by simply piling up plant material in a heap, but this can take a very long time and looks unsightly, A better alternative is to use a compost bin, which are often offered to schools at a discounted rate from the local council, or could be donated. Proper compost containers keep the compost ‘tidy’, help to discourage rats and speed up the process by making the compost mix warm and moist.
Identifying and collecting compostable waste
Split the class into two teams, each with an identical bag of ‘rubbish’ (laminated pictures rather than the real thing!) and ask them to race against each other to sort into compostable, recyclable and other types of waste.
Provide plastic boxes with lids to classrooms for the collection of compostable waste. Appoint ‘Compost Champions’ to collect the waste each day and add to the compost heap (mixing in with a fork) at the end of each week. They can make posters to highlight the importance of composting.
Worms and wormeries
One way of helping to create perfect compost is to purchase special ‘composting worms’. These look very similar to earthworms, but they are entirely different species (as earthworms live in soil and would be unable to survive in nutrient-rich compost). ‘Starter packs’ of worms can be pur- chased, or a local gardener may donate some later-stage compost which already contains an abun- dance of worms. Composting worms are a mixture of tiger worms, red worms and brandlings.
An alternative to a compost bin is a wormery which can be bought, or you can make your own us- ing a transparent plastic container (if you want to view the worms in action) or a pile of old car tyres on a paving slab. (Contact Juliette Green at firstname.lastname@example.org for more information about how to create a wormery.)
Allow pupils to (carefully) look at worms, through magnifying glasses or micro- scopes linked to the computer, and look at the structure of their bodies—no legs, segmented bodies, a ‘saddle’ in the middle. They can also research and study worm life cycles, their roles in food chains and how they move (by stretching and con- tracting its body muscle, which moves the segments along one after the other).
You can introduce the term ‘detritivore’, which means that worms eat dead/ decaying matter. Tell them the fascinating fact that a worm eats and digests up to half its body weight in waste every day!
Younger children can practise moving like worms in dance lessons.
Write a diary of ‘A day in the life of a worm’; read and write poems and stories about worms; create non-chronological reports about worms.
Make life drawings of worms, based on photographs or observations from your wormery. The pupils could also make their own worms out of old socks, adding the ‘saddle’ from a different colour of fabric.