Will held his middle finger tightly and squeezed. The sterile lancet pierced his skin and a moment later a bead of blood oozed out. He smeared it onto a slide, slid it under a microscope and discovered, for the first time, that his blood group was AB+.

Will, 15, may not realise it but he is one of a few children still able to do the kind of hands-on science that has been outlawed by red tape and safety fears in many schools.

When Andrew Allott, Will’s teacher at Shrewsbury school, posted a call in an e-mail discussion group for schools to reintroduce “blood practicals”, his suggestion was greeted with remarks such as “mad” and “hope you’re not sued”.

“No state schools are doing the blood experiment any more,” he explains — it was banned a decade ago when worries about HIV infection were at their height.

So when he decided to do it at Shrewsbury, a boys’ boarding school, he felt like he was “putting his head on the block”.

But now it looks like Allott, a calm enthusiast who lets pupils handle tarantulas in his lab and takes them on trips to track rare species in the rainforests of Honduras, may yet have the last laugh.

Boring, safe, anodyne science is switching kids off in their thousands: numbers on A-level science courses are falling, degree courses are unfilled, university chemistry departments are closing. If teachers can’t do interesting experiments and lessons end up “with kids doing nothing but copying notes off the board, no surprise they are turned off science”, says Allott.

Finally, the powers that be are waking up to the problem.

Last week Sir Digby Jones, director-general of the Confederation of British Industry warned head teachers that children must be allowed to take risks. Jones said his worries extended to the curtailment of the experiments and trips that made science fascinating.

“As a nation we have got to make science interesting,” he said, and turn out inquisitive children eager to explore if we want to compete economically and technologically in the future with countries such as India and China.

Jones is in favour of fizzing test tubes and bangs in chemistry, the dissection of eyeballs and field trips to explore nature at first hand.

“But if you are a science teacher who is told that if he takes a child out on a field trip he has to spend ages filling in forms and then — if a child does what comes naturally (God made them inquisitive) and there is a problem — you could be sued and might even end up in prison, why would you bother?” Allott knows first-hand just how much red tape there is. “The blood experiment took half a day of form filling, chats with the school doctor and permission slips to all parents,” he said.

“If you are setting up a day in the hills it might take one hour to assess the risks and fill in the forms. We have never not done something because of risk assessment,” he says. “But I can imagine other schools thinking, ‘Oh phooey, forget it’. Many schools now do not take kids off site.”

So how risky is it really? Not at all compared with the kind of adventures Allott had as a teenager at Atlantic college in south Wales — the ones that inspired him to spend his life teaching science. He talks blithely of days spent on the hills and of racing dinghies in the Bristol Channel.

But now? Have any of his pupils ever had an accident? “No, no,” he says. “Some years ago we were out on the hills in north Wales and a boy collapsed. He was unconscious for 40 minutes. We called the Sea King rescue helicopter and went with him to hospital.”

Nobody found out why he had collapsed; he was fine afterwards. As Allott says, the kids got to see what the RAF described as “a textbook response” to the incident.

For, at the end of the day, life is full of risks and it’s the children who have been taught to take them safely who will triumph.

“I hope the tide will turn in favour of being able to do exciting things safely,” says Allott, already pencilling in his next school outing: spider-hunting amid the peat bogs of an English Nature reserve in Shropshire.