When an 11-year-old boy sticks his hand up in class and asks, in sweet but not quite convincing innocence, what a condom is, how should you react? Do you ignore him, squirm with embarrassment or give him a ticking off for being cheeky?

If you are Chris Mayer, a school nurse in Chester, you might be a little surprised at the question. But you would certainly encourage the boy and his classmates to chat without embarrassment about sex and body changes.

It is this frankness that will tonight see Mayer, 32, collect the community nurse of the year title in the annual awards run by Nursing Standard, the weekly magazine of the Royal College of Nursing. The judges were impressed with Mayer's commitment to increasing the knowledge of puberty among younger boys - an often-neglected group when teachers are planning their lessons on the vagaries of the adolescent body.

Mayer, something of a rarity as a male school nurse, works for the Countess of Chester NHS trust in primary and high schools in the Chester area. He has written Boys Talk, a leaflet about puberty for 10 to 12-year-old boys, and Let's Talk About Sex, which, with a linked website, enables older boys and girls to find information about contraception, sexually-transmitted diseases and relationships.

Before going into schools two years ago, Mayer was a paediatric nurse. But he wanted to get involved in health promotion and was surprised - and concerned - at the lack of information on puberty and sex for younger boys. The Boys Talk leaflet was born, dealing with such sensitive and taboo issues as involuntary erections, wet dreams and body hair. It remains the basis of his work with the younger age group.

"We usually do it in the last term before they go on to high school," he says. "If the weather's good, we go outside and sit under a tree. I tell them that at the moment they're the biggest and the oldest at school but when they get to high school it's going to be different. We talk about the changes that are happening to the big boys.

"Most of them are a bit shy to ask questions and we don't really have a discussion like I do with the older children. Some of them have heard about puberty and what's likely to happen, but if they haven't, that's OK. It's good to know that they might be a little bit prepared."

Sandra Rote, one of the award judges and a health visitor of many years' experience, agrees that younger boys often miss out and that the bewildering changes puberty brings can come as a shock.

"What impressed me about Chris's entry was that it targeted a group that is often neglected in health education and health promotion," she says. "There's a lot of information out there for women and young girls, but there's very little for boys.

"I think some of it is to do with being a male in a particularly female workforce - school nurses are predominantly women. Chris has come at the lessons with that viewpoint and it shows. School nurses can learn a lot from him."

Government guidelines on sex education stipulate that primary school children should not be taught about sex. Mayer is keen to work within the guidelines, but if a child asks an awkward question he cannot ignore it.

He says: "Last year a lad said to me: 'What's a condom for?' And he was only 11! He threw the question at me as if he knew the answer. I asked if anyone else knew and one lad put his hand up and said: 'It stops girls getting pregnant and boys getting Aids.' I was amazed."

Chatting to younger children about sex is a minefield, as Leeds school nurse Sue Brady found to her peril. She became a cause celebre six years ago when a 10-year-old child asked her a question about oral sex which she answered as honestly as she could. One of the children's parents found out, complained to the school and Brady was headline news - reducing media pundits and politicians to near apoplexy.

Things may have calmed down a little since then, but Mayer is aware of the need to tread carefully. "In one of my high schools there's a parent from Holland, where the whole ethos and approach to sex education is different," he says.

"I wouldn't have a problem discussing drugs and contraception with 11-year-olds, even though I don't because of the guidelines. Because you talk about something it doesn't mean they're going to go off and do it."

Generally, parents are eager for their children to learn about puberty, he says. "Most schools send a letter out a couple of weeks before, saying that I'm going to be talking about puberty and if they want to take their child out of the class they can. I've never had any parent do that. We have a parent day where I show them the video and tell them about what's going to happen. I think some of them might be relieved that I'm discussing this with their kids, rather than them having to do it."

As he collects his prize this evening at the Café Royal in London, Mayer hopes he is setting an example for other school nurses to follow. "Now I've won, I would like to get more people doing what I do," he says. "What I'm trying to get across to other school nurses is that it's not that hard to teach children about these things. It's actually really good fun."