They call it the "Kes effect" - after the moment in Ken Loach's film when games teacher Brian Glover lives out his Bobby Charlton fantasies and flattens kids half his size charging for goal in what's supposed to be a football lesson.
Peter Whitlam winces. It's the funniest scene in the film and it represents everything you shouldn't do when teaching PE. "There's nothing wrong with joining in a game, putting a foot on the ball and getting pupils into space to get the ball to the ones who haven't been involved much - but you don't play a full part."
Mr Whitlam is general secretary of the British Association of Advisers and Lecturers in PE (BAALPE). The organisation represents anyone involved in PE teaching, a responsibility that worries many new primary teachers - as emails to the TES website forums show. They're still getting to grips with a classroom of seated children when they have to marshal them as they hurtle around a sports hall.
How do you keep an eye on several groups all involved in potentially dangerous activities? Especially when you've spent the years since your own schooldays avoiding any form of exercise. There is no set minimum amount of training in primary PE - although there are "competencies" to be met. John Matthews, chief executive of the Physical Education Association (PEA), says seven hours seems the norm, even on undergraduate courses. "It's no wonder primary colleagues come out feeling unconfident or incompetent," he says.
Trainees often get no overview of safety principles. "It's usually addressed through particular activities - swimming or gymnastics," says Mr Matthews. "You need specifics on how to arrange gym apparatus and so on."
But there are common principles. The PEA and BAALPE offer advice to worried teachers on their legal responsibilities as well as practical tips for safety. Under the Health and Safety at Work Act 1974, ultimate responsibility for drawing up safety policies and ensuring they are implemented lies with the employer - usually the local authority or foundation. Teachers have a duty to follow those policies, report hazards and do what they can to avoid injuries.
For example, says Mr Whitlam: "There's a leak in the sports hall roof; there's a risk of slipping on a wet floor. You must inform the head.
Obviously no one's going to fix it overnight, so each day you must do what you can, mopping it up, making it safe and warning pupils about it."
The temptation for nervous teachers is to avoid pushing pupils for fear of accidents. Good PE is all about a balance between appropriate challenge and acceptable risk. No lesson can be 100 per cent safe, Mr Whitlam says, but serious accidents are rare. With 8.3 million primary and secondary pupils taking perhaps 300 million PE lessons a year, there are around three deaths a year, according to BAALPE, and 5,000 injuries that require three days or more off school or a trip to hospital.
"More than any other subject, previous learning is paramount," says Mr Matthews. "If you ask someone to write an essay when they can't write, that's distressing, but not life-threatening. You don't ask someone to swim 100 metres if they've never been in the water."
The key lies in staying alert, getting to know the equipment and checking it regularly. Make sure pupils know exactly what they are supposed to do - and what not to do. Keep records of pupil progress. Log near-misses. "Good risk assessment reflects what might have been," says Mr Matthews. Suit your teaching style to the activity: children can explore ways of crossing a gym mat, but there's only one way to throw a javelin.
Primary teachers used to be able to seek help from the local authority PE adviser, but they are a vanishing breed, says Mr Whitlam. The Government's network of school sports co-ordinators are based in secondaries, but offer support to link teachers in local primary schools, who, in turn, support their colleagues and co-ordinate their sports activities.
For advice and certificated PE safety courses, contact BAALPE on 01746 769487, or the PEA on 0118 931 6240. Safe Practice in Physical Education is published by BAALPE, pound;36.50 inc pamp;p, tel: 01384 813706
Fun and games: PE without the pain
* Stand where you can see as much of the class as possible
* Use common and approved practice - don't improvise
* Pupils need progress - build up the level of challenge and don't make them do things they're not ready for
* Pair pupils of similar size, ability, experience and confidence
* Use equipment for the purpose it was designed for
* Follow the principles of safe exercise, such as warming up
* Don't get fully involved in a game; avoid the Kes effect
* Be a tough referee - make sure pupils know the rules and stick to them
* Involve pupils in their own safety
* Think through a lesson logically - what could cause harm? Have you covered it?