Paper is ideal for primary investigations into properties of materials, says Ray Oliver.
Suddenly paper is in the news. Prompted by National Science Week in March, children everywhere have been cutting, folding and sticking bridges, parrots, helicopters and planes. You can even buy a book on "molecular origami". Children have always been fascinated by the properties of paper - it seems amazing the science curriculum failed to include the playground game "scissors, paper, stone". It is an effective way to investigate the properties of materials. The science and technology of paper are an ideal focus for practical activities.
Wasps and papermaking
A good place to start is with an unusual and unpopular natural paper construction.Wasps are talented papermakers, using the material to construct their elaborate nests. As with manufactured papers, the range of raw materials employed by the wasps is very wide. It includes dried leaves, grass fibres, bark and rotten wood. The wasps peel off strips of fibres, which they manipulate and stick together with a natural adhesive to build the structure. The bands or stripes you often see on these paper nests reflect the choice of raw materials. The complex architecture of paper cells in the nest demonstrates how versatile paper can be as a building material. When pupils investigate the properties of paper they will see that it can be shaped, reinforced and made waterproof while remaining light and strong. Ideal for the wasps.
A closer look at paper
Papers people use are made from fibres, mostly derived from plants. The source can be cotton or flax, wood or esparto grass, straw or bamboo. Children can use a hand lens, low-power microscope or overhead projector to look closely at the fibre mat in newspapers or other coarse papers. When converting paper into papier mache, the mat of fibres is loosened ready to be used again. Children can experiment with laying bundles of fibres in different patterns to find the best way to produce a strong material that resists tearing when the paper is completely dry. Paper for fashion magazines looks and feels different from newspaper. It has an added filler, often china clay, to plug the gaps between the fibres and produce a smoother finish. This is why the children will be unable to see the fibres in filled papers of this type.
Going for the burn
(Remember the risk assessment first.) Everyone knows that if you put paper in a flame it will burn. Everyone may be wrong. Ask the children to choose a paper that remains waterproof for at least five minutes. Fold or shape the paper so that it can hold a small amount of water - 50ml is enough. Place the paper container and water over a gas flame or on a red-hot electric ring. Instead of catching fire, the heat is conducted to the water causing it to boil. As long as some water remains, all the heat goes into causing a change of state from liquid to gas (steam). Once the water has all boiled away the paper will indeed catch fire. Only the brave (and insured) will wait this long.
Pupils can experiment with reading secret messages sealed inside a paper envelope. Some papers become almost transparent when treated with a suitable liquid. Apply liquids such as meths, nail polish remover or sunflower oil, or even petroleum jelly, using a paintbrush. Pupils need to check which liquids and which types of paper become transparent, and whether the change is reversible to cover up their spying. They may find it necessary to hold the envelope up against a bright light or daylight. Real secrecy requires invisible writing and plain drawing papr works best. Try writing messages with strong sugar solution or lemon juice or even milk, Once the writing is dry check that it has become invisible before making it reappear by warming over a hotplate.
When some papers are held up to the light, a design can be seen within the structure of the paper, the watermark. Watermarks are produced by pressing a 3-D relief design into the wet fibres during manufacture. The variation in thickness and compaction of the fibres that this causes is preserved when the paper dries. This fixes the watermark permanently. Ask pupils to find examples of watermarks in commercial stationery or even banknotes. Make a window display which allows daylight to shine through the samples. If you use papier mache to make your own handmade paper, try pressing plastic letters or other relief design into the surface before it dries. Check the watermark when completely dry.
Bursting to tell you
(Eye protection needed.) One fun way to test the strength of different papers is called burst testing. Ask the children to cut 15cm-side squares of different papers, ranging from tissue to brown wrapping paper. Stretch one square over an empty beaker and secure using an elastic band. Using a metre ruler set vertically, drop a ballpoint pen on to the paper sample. Increase the height of the drop each time until the pen bursts through the paper. See how the burst strength of the paper samples compare, if necessary adding weight to the pen using Plasticine or similar.
Cut the windows out of some old window envelopes. Compare the effects of looking through the paper window at a distant object with placing the window directly over some text. Cut the paper window material into thin strips, about 0.5cm wide. See if these strips respond to different temperatures by changing shape, for example when placed on a radiator.
Until the end of the 18th century all papermaking in Britain was done by hand. There were hundreds of small paper mills but their output was small. Paper had its own industrial revolution starting in rural Hertfordshire in 1803. In this year the Fourdrinier brothers set up a papermaking machine in Frogmore Mill, Apsley. The paper was made in a continuous reel instead of in separate sheets as before. The reel was then cut into large sheets and left to dry. Within 25 years, half the paper in Britain was machine made. John Dickinson, the founder of the famous stationery company, bought Apsley Mill in 1809 and his company remained in business there until 1999.
'An Afternoon with Paper' published by the British Association as part of the 2001 National Science Week. British Association, 23 Savile Row, London WIS 2EZ. Tel: 020 7973 3000
'Molecular Origami', by Robert Hanson. Precision scale models (UniversityScience Books, Sausalito California) A 'Schools Resource Material' catalogue including 'Six Pack Science for KS2', which gives details for making paper by hand, is available from The Paper Federation, Papermakers House, Rivenhall Road, Swindon, SN5 7BD. Tel: 01793 889605
The Paper Trail, Apsley, Hemel Hempstead is being developed as an interactive visitor attraction to open in 2002. It is the site of the first papermaking machine in 1803. Apsley Paper Trail, The Cottage, Apsley Mill, London Road, Hemel Hempstead HP3 9RL. E-mail: firstname.lastname@example.org Papermaking by hand demonstrations are an added attraction for school visits to the caves site at Wookey Hole Mill near Wells, Somerset BA5 IBB. The mill registered its own watermark in 1783. Tel: 01749 672243