Tim picked up a hammer, made like it was a machine gun and mowed down his classmates.

In a design and technology lesson Dan lined up some dust along his ruler and then flicked it at the boy working opposite.

Moments later the boy retaliated. A handful of dust, secretly gathered, was tossed at Dan with a nifty backward throw.

Punching and pinching, collar grabbing and wrestling holds, bag fights and sword fights are just a few of the everyday occurrences in classrooms and corridors in this Sheffield secondary school.

But in more than 60 hours of video-taping, only one incident involved a girl.

For many boys, being a lad is vital to their self-image, and detention or being sent out of class is viewed as a badge of courage.

Research by Carolyn Dixon from Sheffield University has shown that playfighting is commonplace, opportunistic and sporadic. Rulers, pencils, anything that comes to hand is fashioned into a weapon. Pretend grenades are lobbed and bats whacked in the air.

However, this is between friends, not enemies, and there is no intention of inflicting physical harm. But with boys falling behind girls in GCSE exam performance, laddishness is a cause for concern.

White working-class boys, who have been sitting exams over the past few weeks, are likely to find they have lost out compared to girls and Asian boys when results are revealed.

Analysis of league tables has made it clear that in most schools they are performing less well than girls, even in subjects usually regarded as “theirs” - physics or design and technology. Boys are continuing to do worse in English, language and the humanities.

At a conference on the gender factor in exam results last week, Bernard Barker, head of Stanground College in Peterborough, revealed that for many boys the worst possible thing was being thought of as a girl - someone who worked.

His comments were based on research among Year 9 students at his school. Further studies conducted in Stanground and at two other secondary schools disclosed that a quarter of boys did not attempt to do their homework compared to 17 per cent of girls.

Mr Barker said there was a strong male agenda. “It’s about being mates, having a joke and not being a girl.”

Dr Mel Vlaeminke, a lecturer at Leicester University, which organised the conference in conjunction with the local authority, said: “We have got to find out what is going wrong.

“It is not uncommon for nearly twice as many girls as boys to gain five or more grades A-C at GCSE and for boys to dominate the figures for exclusions and special needs.

“Is it that girls are more intelligent - or that their early upbringing makes them better socialised for school life or better equipped to use language, enjoy reading and organise their work better?

“Do boys get caught up in a peer group culture which tells them that hard work isn’t macho but messing about is?” A survey of 10,000 Leicestershire secondary students revealed girls in Years 10 and 11 thought homework was important. They also said they worked as hard as they could. Boys of the same age tended to like lessons with friends, where they could make things, they enjoyed answering questions and believed they were getting good marks.

Carolyn Dixon, who has captured the antics of a group of Year 9 pupils in design technology lessons on video, said: “When I talk to them about them, they say it’s a joke to break up the boredom.

“What we are seeing is tensions being played out by an individual trying to assert his independence.”

Many of the boys are already much influenced by football, and Euro 96 fever will have undoubtedly gripped their classes. Whether it will affect boys’ performance at GCSE this summer would make an interesting research project.