I don’t have the nerve for what they serve, So Mum can I have a packed lunch?

Richard Stilgoe’s schoolchildren’s song sounds a little outdated now, as school meals often include exotic salads, pizzas and other appealing dishes. But plenty of children still arrive at school with a lunch-box. There are many reasons. Some children are so choosy that only a home-prepared lunch will do. Some parents believe they can prepare a better, or cheaper, meal at home - but any who think they are providing their child with a carefully balanced lunch can’t have seen the trading (“swap my yoghurt for your crisps”) or just plain ditching of food that goes on when dinner assistants are not alert to it.

But the packed lunch - and the box it comes in - is a great starting point for exploring many interesting curriculum ideas.

Not just a plastic box

Take the box, for a start. Modern lunch-boxes are made from smooth, easy-to-wash plastic. The curves aren’t just easy to clean, with no awkward corners where food scraps can collect, they are also beautifully shaped to ensure the thin plastic sheets are rigid.

You can see that even better in a cheap substitute - the ice cream container. These vacuum-formed boxes (you can still see the scar on the bottom where the box was attached to the “sprue” - the umbilicus of the forming machine) are made from plastic so thin that without careful design it would collapse. In a similar fashion to car panels, the sides have been carefully creased and reinforced to add strength. Look for the “webs” in the corners and along the sides, adding rigidity. The rim doesn’t just form a seal when the box is shut, it also stiffens the box shape.

Food wrappings are similarly hi-tech. Yoghurt pots are given rims and creased for strength. Crisp packets and chocolate wrappers are odour-proof - otherwise your apple could end up tasting of smoky bacon, or your chocolate bar smell of chicken tikka sandwiches.

Long-distance travellers

The growth in communications means that we no longer have seasons for food. The fruit in the lunch-box may have travelled from Australia or the Caribbean. The flour in the bread rolls could be from Canada. The potatoes in the crisps might have grown in the Canary Islands. Cranberry juice has been a huge success for the eastern USA, where blending with blackcurrant and other juice has made this vitamin-rich but acid fruit palatable.

A little map work and a simple sum will give you the total number of miles travelled by the contents of a lunch-box, and raise the question of whether there may be less distant, and more environmentally friendly, substitutes.

Labelling is informative, as well. Ingredients are listed in quantity order: potatoes first for crisps; “peach 6%” for a fruit yoghurt (but also “contains milk”); “water” for a fruit juice.

A surprising range of food contains sugar, including some flavoured crisps. Apparently healthy fruit-and-nut bars (“hamster bars” to children) can contain sugar; and many foods contain quantities of salt. The nutrition information makes an interesting study, too. What is “dietary fibre” and why does it appear so rarely?

Long-term survival

It’s no pleasure to find a lunch-box at the beginning of a new term that should have been emptied at the end of the last. The smelly contents are best left unexplored. Why does this happen to food? It decays, of course. Bacterial and fungal action breaks it down.

Food manufacturers know this - hence the “sell by” and “best before” dates. Natural decay has been combated in many ways. Early sailors ate food that had been preserved in salt or pickled in vinegar. Napoleon’s cook put cooked food in old wine bottles, sealing them while they were still hot. Sctt took canned food to the Antarctic. Samuel Johnson is supposed to have eaten, on his return from a journey to Scotland, a chicken that he had buried in snow before leaving London.

All these methods worked on the principle that bacteria and fungi will live and reproduce in a warm, wet environment. The canning processes kill them and make the food sterile. Chilling slows, and freezing virtually stops, their activity. Salt and vinegar, and sugar in jam, produce conditions where the water is sucked out of their cells.

But opening the jam pot lets air in. Water vapour in the air condenses on the lid, drips into the jam, and forms a small pool where micro-organisms can live and reproduce - and they do, eventually topping the jam with a thick furry coating.

LUNCH-BOX ACTIVITIES

Shape and position

Look in a lunch-box for cuboids, spheres, shapes that will roll and shapes that will stack. Use the language of position to explain where things are in the box - for example “inside”, “next to”, “on top of”.

How many?

Estimate how many crisps, biscuits or snacks are in a packet. Check by counting. How close were you? Estimate how many crisps will be eaten today, by the class or by the whole school.

How much?

Look at the information on crisp packets or other containers telling you how much they hold. Collect some empty containers and put them in order, starting with those that hold the least. Sort packets by size, for example put those that hold more than 50 together.

Data handling

Do a class survey of what is in lunch-boxes. How many children have drinks, fruit, crisps? What flavours of yoghurt or crisps? Empty crisp packets can be arranged in an instant graph of flavours.@Activity subhead 1a = Food values Look at crisp packets or other wrappings. Using an enlarged version may help. Use the information on the wrapping to answer questions, such as “How many grams of fat in this yoghurt?” Geography

Where did our food come from?

Stick clean packaging on a world map, learning the countries and products. How far has our food travelled? Who has the longest-distance lunch-box? What local foods could have been substituted? Can we plan a “sprint” box in which all the food has come a short distance?

Science

What should a lunch-box contain?

Food for growth and repair, food for energy, food for health. Explore two specially prepared lunch-boxes - balanced and unbalanced. Compare the contents.

Explore the food requirements of a child of your age. How far does a packed lunch go towards meeting them - especially the vitamin, mineral and fibre content?

DesignTechnology

Design some attractive food packaging for a healthy snack. Notice the important information - nutritional, dietary, country of origin, the manufacturer’s address, dates and packaging marks - which is legally required. Does the packaging clearly reflect the contents? Foods in packets resembling motor oil or baby food have not been a success.

LUNCH-BOX HISTORY

Use this activity to develop children’s understanding of the way we use evidence to reconstruct past events.

When pupils come in after the dinner break, borrow a lunch-box from one of them and challenge the rest to work out what it originally contained. Begin with the physical evidence. Look at empty packages, and cartons. Are there any clues to other kinds of food which the box might once have held? Now question eyewitnesses who were present when the owner ate the lunch. What can they remember about what was originally there? Look for gaps or conflicts in their evidence. Finally, ask the owner of the lunch-box for confirmation of the answers.

Teaching points to bear in mind are that eyewitness testimony is not always reliable - evidence about a shared event often conflicts; and it is not always complete - there may be gaps and these can influence our interpretations of past events.