Amanda Castleman talks to an environmental teacher with a difference . . .

Valdir Bento's hands have wrestled crocodiles, squeezed boa constrictors and built huts in the Amazonian rainforest. But his handshake is surprisingly soft, as befits a teacher of small children.

The Brazilian physicist runs an environmental education project, which flourished for nine years in Portugal.

Now he is launching the Amazonia Conference in the UK, beginning next month in Oxford, where Valdir is based.

That means local Students - primary, secondary and University - can win free trips to South America. Valdir's project is not limited to earnest proselytising and slides: he shows nature first-hand, in all its red-toothed, sharp-clawed glory.

He uses the Amazonia rainforest as a hook for environmental issues facing the whole globe. At each school, a two-hour lecture is followed by a study period and test. The first-prize student wins a free ten-day trip to "learn in practical terms, the deep and beautiful lessons offered by our planet's greatest forest".

He says: "We are not just interested in the Amazonia. There is a more subtle message behind the project. We want to form kids with minds which will be better that the present generation's.

"Without education, the environment has no hope of recovering. This is not a radical view. If people are not educated about certain problems, they do not care about them. It is human nature."

The dilemma is bigger than most realise. "People think about the oxygen problem, how the rainforest purifies and contributes to our air," he explains. "But that is less important that species diversity. Fifty per cent of all living species dwell there. A problem with the Amazon is a problem with more than half of our living heritage."

The ten-day expedition concentrates on practical lessons about nature, involving museums, boats, riverbanks, islands and the forest. Students spend two days in the city of Manaus, which is a very good example of urban Amazonia. Next, the trip stops at the famous tree-house hotel in Ariau, where an ironic sign declares one platform to be "Tarzan's house".

Here, the expedition once witnessed a rite of manhood, performed in honour of former US President Jimmy Carter.

An Indian chief, wearing full ceremonial feathers and pain, helped a lad don a glove filled with biting ants.

"If the boy does not cry, scream or complain, then he becomes a man and can get married, hunt," Valdir says.

Then the schoolchildren head deep into the heart of the rainforest, face to face with anacondas, alligators and monkeys. A jungle survival course teaches them to make huts and suck fresh water from plants.

They visit the headwaters of the mighty Amazon, where black and yellow rivers intermingle slowly over 16km.

Piranha soup is on the menu, but Valdir stresses that most local fish are gentle and good-natured.

"The pirarucu grows up to 3m long and 150kg, but it is not like the shark. None of our fish are violent except the piranha, which is tiny. But when hundreds attack, they can be deadly.

"We teach the kids about monkeys, how to handle them. All monkeys want is to be treated gently and with affection. Adults often get scared, which monkeys mistake for aggression.

"We visit a man who works with psychologically damaged monkeys, who have been held in captivity illegally. It makes you realise how close monkeys are to us.

"We also catch alligators, just to study, and then release them unharmed. Alligators are photo-phobic, sensitive to light, so we set off a bright flash which paralyses them. With the larger ones, we tie their mouths shut, just to be extra careful.

"This is real life. This is not a zoo," he stresses, gesturing towards a picture of a man-sized reptile belly-up to the camera.

Vadir's physics expertise often comes in handy, though his two occupations seem strange bedfellows. Science, he explains, will play a vital role in healing the environment. "We need to think in practical terms, which is what physicists do. There's a lot of theory around, but we need workable solutions.

"The biggest environmental problems can only be tracked, monitored and solved by physics, like global warming, which requires satellites and lasers. And we use physics to measure the hole in the ozone layer and pollution levels.

"I always joke that physicists have the dirty job in environmental preservation. Biologists and zoologists get to work with all the beautiful parts. But when you step back and look at the planet, you begin to understand how fragile it is. Our planet is presently going through many difficulties. Nature, which we should preserve and pass on to future generations, is under attack every day, in every country in the world, by almost all human beings.

"It is our duty to act. It is urgent. We must inform everyone about the environmental problem. We must educate ourselves, and whenever possible, contribute to the education of others."

The Amazonia Conference does just that, bringing the message to primary and secondary schools. "The conference is free of charge - that way we can reach all the schools, even in very poor areas. We rely 100 per cent on sponsors," says Valdir.

University students are eligible, as the conference joins forces with Oxford University this autumn. A half-day programme on September 9 is open to anyone, as is the chance to win a trip to Brazil.

"The leaves falling in autumn and the whales moving in the sea. The flight of the butterfly and the swift leap of a tiger. The grey dolphin swimming in the rivers of Amazonia. The seed of weed growing and a child's first steps. For the simple and sacred right to continue having all this, any effort is valid.

"Let us then bring education for preservation," he concludes.

Contact Valdir Bento at Rewley House, 1 Wellington Square, Oxford or 0798 990 6751/01865 270360.