This is the question Simon Lee, a science teacher at Compton School, Barnet, puts to his pupils as part of a drive to promote global perspectives on the subject. The common assumption among pupils, he says, is that herbal medicine is just mumbo jumbo and they are surprised when he explains that in fact these medicines have been developed using scientific procedures over thousands of years and hundreds of millions of people rely on them.
"We have to get them to accept that western discoveries are not necessarily the best," he says. "We look at the advantages and disadvantages of both, for instance at how herbal drugs are cheaper, more accessible and have fewer side effects."
Simon Lee is one of 200 science teachers who since serving with Voluntary Service Overseas (he taught in Papua New Guinea for two years) have joined its science teachers' network to help spread some of the cultural understanding they gained in their time abroad.
Through the network, returned VSO volunteers run training sessions for other teachers and have produced a series of photocopiable resources on topics such as fuel, nutrition, housing, sound, astronomy, rainforest remedies and soap, which can be dealt with in two or three lessons each.
Ann Childs, who co-ordinates the network and is a teacher trainer in chemistry at Oxford University, says a key part of teaching a global perspective is challenging pupils' prejudices about people in developing countries and to do that requires staff to be confident and knowledgeable. In her own research into pupils' perceptions of Africa she found that the most frequently used words were "famine", "mud huts" and "primitive".
Staff have to he able to counter the remarks that pupils make about other cultures the moment they are made. For instance, in Liverpool when she was teaching a topic on soap, examining how it is made in Tanzania and why it is cheap there, one boy said it was because they never wash and are always dirty. "I had the knowledge and was able to say that when I was in Tanzania people washed twice a day because it was so hot," Ann Childs says.
In trialling the network's resources the teachers realised that there is always a danger that raising development issues will reinforce the image of people in these countries as passive victims - whether of famine, war or another disaster.
They found, for example, that their materials on the Bhopal disaster when taken on their own would put across an entirely negative image, so it was important to use back-up materials that showed the parallels with other chemical disasters in European countries.
In fact in a number of scientific topics it is quite easy to show how methods in developing countries can be superior to our own. For instance, when it comes to pest control our farmers have shot themselves in the foot by growing the same crop across an entire - and often very large - field. Because the crop is uniform, pests spread quickly and can only be controlled by chemicals. By contrast, Simon Lee noted that in Papua New Guinea farmers would grow a mixture of up to seven crops even in small areas, which meant each crop was spread out too thinly for pests to proliferate.
"People assume western technology is better because it is modern," he says, "but in lots of ways it's not very clever. Western scientists keep trying to breed resistant crops but the diseases overcome the resistance."
Even within developing countries modern, more "scientific" methods can compare poorly with traditional ones. Simon Lee uses a videopack - Science for Survival - from the International Broadcasting Trust to look at the nitrogen cycle in two different farming sectors in India. In the modern sector farmers use a lot of manufactured fertilisers which seep into rivers. This causes abnormal algae growth and the animal life in the water dies, as has happened in parts of the Norfolk Broads over here. But traditional farms use compost and animal manure as fertiliser and the nutrients in these don't dissolve as easily, so when it rains they don't get washed into the river.
In an attempt to broaden children's understanding of science in other countries, VSO helped Peter Barnes, a science teacher at Tideway School, Newhaven, to get the support of his school to spend a year visiting classes in India. He will be gathering materials on how they teach the subject and how villagers make use of science. VSO's materials are also being revamped to address a greater range of ability.
"It's easy to talk about the difficulties people have without pointing out the advantages of different lifestyles and the parallels," says Peter Barnes, who worked for VSO in Tanzania. "We also need to get away from painting people in the developing world as victims. We have to get over that they have to be a lot more inventive to do things that are quite simple for us to do."
All the teachers felt it was important to push this global slant in science because these issues will be taken more seriously in a mainstream subject than if relegated to a special lesson on, say, racism. For Simon Lee, based in a multiracial school, there is an added incentive. "It helps kids from different ethnic backgrounds if you are taking their culture seriously as a scientist. By using it as an example you show you respect their culture."
* For more details about the VSO science teacher network contact Ann Childs or Eleanor Kercher at VSO. Tel: 0181 780 2266 * VSO is looking for 120 science and maths teachers to fill two-year posts overseas. Contact VSO Enquiries Unit, 317 Putney Bridge Road, London SW15 2PN. Tel: 0181 780 1331 * IBT Science for Survival videopack, covers agriculture, medicine and genetics, Pounds 18 including pp, from IBT. Tel: 0171 482 2847.