There's blood and tears in those exam scripts...

... so never spill more than two food groups on them when marking, says Kevin Fong

One day somebody will invent the perfect exam. It will be a big doughnut-shaped thing that fits snugly around students' heads to scan their brains for evidence of anything they remember and everything they understand about your course.JIt will spit this out in reams of paper complete with a grade. No fuss, no argument, just the grade the student's brain deserves.

This will save us from many things: endless hours of poring over illegible handwriting, the dangers of giving out undeserved grades or the crime of failing to reward hard work. There will be no need for second marking, no lengthy appeals, no swearing because you've knocked another cup of coffee over the papers. Until then, though, we're stuck with the ancient, repetitive strain injury-inducing ritual of the written paper.

Now, patrolling endless columns of undergraduates, handing out extra paper to the swots, fixing wobbly desks and dishing out spare pens is not a way that anyone would ordinarily choose to spend three hours of their valuable time. But when it is your class sitting an exam that you've set, the whole thing becomes something of a spectator sport.

This, after all, is the ultimate course feedback form, a chance for the students to express precisely how much or little of your wisdom was imparted, an opportunity to test the "Garbage In: Garbage Out" hypothesis, a brief, nerve-wracking moment when lecturers flick the switch from "send" to "receive".

You can get an idea of how you're doing long before you start reading the scripts, before you've even picked them up, in fact. If the whole class turns up for exam kick-off, if they're all there at the end and none of them is in tears, that's a start. If the hall is filled with the sounds of furious scribbling, that's good too. However, forlorn expressions, accusing stares and the occasional missile aimed in your direction suggest that somewhere you went very, very wrong.

When it's all over you go straight home to brew up a couple of litres of coffee and begin wading through the offerings. I feel that to do this properly takes dedication. Ideally, marking should take place in a quiet room with a decent bit of feng shui going for it. It should happen away from DVD players, children, animals, alcohol and recreational drugs. In a perfect world it should happen between mealtimes and if you find yourself at any point with more than two food groups sticking the pages of a script together it's probably time to take a break between mouthfuls.

All this because the metaphorical blood and the literal sweat, toil and tears that cover the pages in front of you deserve to be treated with a bit of reverence. Nothing, it seems, could be more precious or irreplaceable than that stack of scripts. Hopes, dreams and futures depend at least in part on their contents, and the consequences of losing them are truly unthinkable.

So handle with care and, when carting the things around between home, college and second marker, remember the cautionary tale of a hapless colleague who dutifully collected his scripts, shoved them in a plastic bag, fixed this to the carrier on the back of his motorbike and raced off up the M6 for a weekend away. Somewhere along the route he became aware of a faint fluttering and, suspecting mechanical failure, pulled into a lay-by and stopped, only to discover that the bike was fine but that he had been decorating the motorway between Birmingham and Manchester with exam papers.

Kevin Fong is a physiology lecturer at University College London, a junior doctor and co-director of the Centre for Aviation, Space and Extreme Environment Medicine. He is a fellow of the National Endowment for Science, Technology and the Arts.