It’s one of the first ideas that we grasp in science: all living things need energy to survive and grow. Energy is passed along the food chains from one organism to the next. Decomposers and detritivores, such as fungi and worms, recycle leftover nutrients. These interconnected and overlapping food chains come together to make up a complicated food web.
Now think about how humans obtain their food. Farmers grow crops and rear livestock, these are transported to be "processed" and prepared for sale, then transported again to shops. All the while, various types of waste accumulate.
There is a growing movement against these industrial farming processes, with some producers learning from nature – and successful past approaches – by rotating the use of their land between crops and animals. For example, the Polyface Farm in Virginia, USA, is using its livestock to help fertilise its land and remove pests, as owner Joel Salatin explains: “The laying hens scratch through the dung, eat out the fly larvae, scatter the nutrients into the soil, and give thousands of dollars’ worth of eggs as a by-product of pasture sanitation. The pigs aerate compost and finish on acorns in forest glens.”
Older secondary pupils could compare and contrast these innovative farming methods with the monoculture farming which is dominant in the West as part of their ecology unit in science.
And we can also introduce students of all ages to ways of lessening, or even eliminating, waste. Here are four areas to focus on:
Is it right that our food is transported multiple times before arriving in our kitchens? Buying local produce means cutting down on the precious, finite fossil fuels used in the process. Meat that has been reared near to our homes and prepared by a local butcher has a much lower carbon footprint than Argentinian beef that has been shipped in, prepared for a pie in one location and distributed to supermarkets across the length and breadth of the country. Secondary school students could consider these ideas while studying life-cycle assessments of products in science and could compare data about the carbon footprints of locally and globally produced meat.
Much of what we buy from supermarkets is packaged in plastic, which, as the Blue Planet II series highlighted, is causing major damage to the oceans. Pupils could be asked to bring an item of plastic packaging to school and, as a class, they could sort the different types. They could consider why we use different types of plastic for packaging, which ones can be recycled and what happens to the waste that the local authority doesn’t recycle. Different recycling bins could be set up around the canteen or playground to get pupils sorting from their lunchboxes.
Older pupils could be encouraged to write to their local authority to find out why only certain types of plastic are recycled, and they could write to supermarkets to find out why they aren’t investing in using biodegradable materials or even offering consumers the choice to buy their produce free from packaging.
A third of all the produce that’s grown is wasted and if you look in the supermarkets, you’ll see much of the fruit and veg looks uniform in shape and size. Is it really what consumers want? Pupils could conduct a survey of how people feel about “wonky veg” and could even create their own campaigns using the results.
What else can we be doing to change our nation’s wasteful habits? One obvious solution is to plan meals in advance and only buy what is needed. Or we could utilise our freezers more efficiently, defrosting only as required. We could also speak to the older generation and learn from their food habits, particularly when rationing was still commonplace. Ask your pupils to find out what their grandparents, great-grandparents or older members of the community would make using leftover food. You could create a class blog that could be shared with the wider community. Some of the recipes on the BBC Good Food website can make great use of leftovers and are easy for pupils to make in class with the help of an adult, such as bubble and squeak, fast-fix fried rice or vegetable soup.
Some waste is inevitable but tossing mouldy apples or wilted flowers into landfill means moving useful compounds to the rubbish tip and depriving the food chain of vital nutrients. You could encourage your class to start composting food waste and set up a collection system for the whole school. You could buy a compost bin or build one in the school grounds as a design and technology project.
Composting also provides plenty of opportunities for scientific investigations, such as looking at how soil forms or studying the life of worms and other invertebrates. Setting up a collection system will encourage teamwork and communication. You could even make an arrangement with the allotment owners in your area, offering fresh compost in exchange for fresh produce.
There are other questions to ask if we truly want to reduce our waste. It may be appropriate for older pupils to debate bigger ideas such as whether it’s a waste of land or even a waste of water to rear livestock rather than plants, especially as it feeds fewer people. Should humans be growing excess produce that doesn’t contribute to the correct proportions of food groups outlined by the Livewell campaign or the NHS Eatwell plate?
By thinking differently about our consumption and making a few changes, together we can make a big difference to sustainability and show our students how to be the citizens our future needs.
Racheal Adams is head of science at a school in Devon and has taught and led science in a number of schools in the South of England
For more teaching ideas on education for sustainable development, check out WWF’s Plant2Plate resources for schools which offer a huge variety of tasks and topics for discussion. Teachers and leaders wanting to pursue sustainable education further can enrol on the free CPD course on education for sustainable development developed by the WWF.