Discovery

A Week of It

By Vicki Hyde, NZSM

Want to design a playground for a marble? How about making your own electricity? Or you might like to try your hand at moving a "radioactive" egg without touching it.

These are just some of the activities going on around the country as part of Science and Technology Week, running from April 26th to May 2nd. The biannual event is aimed at highlighting science and technology as exciting, relevant and challenging, and of importance and interest to the whole community. The bulk of the events are being run by the hands-on science centres and schools, working in conjunction with the New Zealand Science Teachers Association and the Royal Society of New Zealand.

Many of the science centres are running special shows, demonstrations or lectures as part of their Science and Technology Week activities. Dunedin's Discovery World has had help from Dunedin Electricity in producing its "Electricity in Action" exhibit, complete with a fully-functional mock kitchen. Visitors can make their own electricity, transmit it, and see how it is used in a variety of typical appliances. The exhibit includes information on energy efficiency and alternative energy production.

The exhibit will tour the other science centres at a later stage. It is particularly appropriate for Dunedin, says Discovery World's Kathleen Rice, as the nearby Waipouri Power Scheme, built earlier this century by Dunedin City Council, is the country's largest "private" electricity generation scheme.

Science Alive! in Christchurch will show off its close ties with the Deep South, with a model Antarctic field camp, and videos and lectures on Antarctic research. The camp, complete with polar tent, sledges and food boxes, is being supplied by the New Zealand Antarctic Programme, based in Christchurch.

Marble Mania

One of the activities attracting interest is the "Playground for a Marble" competition being run by a number of the science centres around the country. The basic concept is to build a structure which will allow a marble to fall for the longest possible time with no energy source other than the conversion of gravitational potential energy to the marble's movement. The size of the playground is specified and the "marble" is to be a steel ball bearing 16.5 grams in mass and 15.875 millimetres in diameter.

Capital Discovery Place, Wellington's Science Centre, has been whittling down the entries from four regional competitions and expects to see 40 or so finalists in the play-offs. The ideas for the playground have surprised and intrigued Ann Whyte of CDP.

One group were exploring using a magnet to slow down their marble, but were concerned that this would contravene the injunction against using other energy sources. Another group came up with the idea of rolling their marble through a "viscous substance" -- classroom glue. The main problem with this idea appears to be ensuring that the marble comes out the other end. There are also bonus points for converting the kinetic energy of the marble to other forms of energy such as sound, light or heat.

"They're thinking of all sorts of things," says Whyte. Lego have donated prizes and an electronic Lego sensor system will be used to accurately time the fall of the marble.

In further encouragement of lateral thinking and scientific inquiry, BP Technology Challenges are being held around the country from Auckland to Invercargill throughout the week, and from primary through to secondary school level. Teams are able to prepare their solutions to a specific challenge (such as transporting that radioactive egg) and are also faced with on-the-spot problems designed to test their ingenuity.

The challenges attract a lot of enthusiasm from schools. Four small country schools -- Whareama, Tinui, Castlepoint and Okautete -- joined together for their own Technology Challenge event, together running a day of art, sports and science. Almost a thousand school students are involved in the Wellington area events, and Peter Spratt of Teacher Support Services says that they had to limit entries.

"We had more than we could handle," he says. Prizes of book vouchers and Lego sets have been donated by BP, as has vital equipment, such as corrugated cardboard from Kiwi Packaging and sellotape from Edutech. The latter two will come in handy for constructing the cardboard seat that forms one of the challenges. Spratt has a personal interest in the outcome of this particular problem -- the seat has to be strong enough to support his weight.

Teaching Teachers

While many of the week's activities are aimed at school students, the focus in Palmerston North is on teaching teachers. They'll be learning more about technology, with a series of site visits arranged with local organisations. At the police station, teachers will learn about the use of forensics. They'll see solvent extraction technology at New Zealand Pharmaceuticals and clover production technology at HortResearch. Massey University's Technology Faculty is providing demonstrations of electronics and biotechnology.

Lots of visits get organised for schools, says Science Centre Director Peter Millward, but not that many teachers get a chance to learn about the role of science and technology in the area. Some 150 schools within 80 kilometres of Palmerston North have been approached to take part in the teacher visits.

Palmerston North is one of the best places to try such an initiative according to Millward, as he contends that it has more PhDs per capita than any other city in the Southern Hemisphere.

"We hope that teachers will go out and have a look and realise when they talk about science and technology that there's heaps of it going on outside the classroom," says Millward. The teacher visits will go some way towards demonstrating how technology functions in the real world. The development of the technology curriculum for schools means that there's going to have to be an awful lot of teacher development too, Millward says.

Planning is already under way for the 1995 Science and Technology Week. While this year's event has been low-key, those involved hope to see more sponsorship and greater community involvement in the next Science and Technology Week.

"It takes a lot of time and energy to put something like this together," says Millward.

What I want to know is ...

...why do leaves change colour in autumn?

Leaves start out green because their cells contain tiny packages of a green pigment called chlorophyll. This chlorophyll lets the plant absorb energy from the Sun. There are two types of green chlorophyll, called chlorophyll a and chlorophyll b. Other forms of chlorophyll are brown, golden-brown and red.

Chlorophyll is held inside small structures called chloroplasts, which float inside the bigger mesophyll cells in the centre of the leaf. Also inside the leaf cells are carotenoid pigments, which are red, orange and yellow. Tomatoes and carrots, for example, have a lot of carotenoids, making them red and orange instead of green.

In autumn, the days get cooler and shorter, and this triggers a change in the production of pigments. The green chlorophyll starts to break down, and the red and yellow pigments begin to show more clearly. In some cases, more red and yellow pigments are produced in autumn, but botanists are not sure why.

The fact that chlorophyll actually breaks down inside the cell is a recent finding, according to Dr David Leung, of Canterbury University's Plant and Microbial Sciences Department. Despite many years of plant study, the work on chlorophyll is still in its infancy, he says.

The colours of leaves in autumn -- how bright they get and how long those colours last -- are different in different parts of the country. In Auckland, autumn is not so obvious, as the leaves tend to stay green until they fall off the trees. Arrowtown, in Otago, is famous for the bright golds and reds of its autumn leaves.

Dr Leung says that botanists think this has something to do with the change in light quality the further south you go, but they're still not sure. It happens around the world, but in the Northern Hemisphere the brighter colours are found further north. The change in day length as you get closer to the poles may be a factor, he thinks.

Vicki Hyde is the editor of New Zealand Science Monthly.