It’s 8.20am in pretty much any staffroom in the land. There are assorted teachers scattered around, some reading a newspaper, some drinking tea, some frantically trying to locate the worksheets needed for their class. Someone comes in brandishing a sheet of paper and attaches it to the notice board. Everyone, even those who were to all intents and purposes comatose, flocks to the board. They cluster in a tight huddle, their necks straining to read the small writing on the grid.

Some smile quietly to themselves and adopt a rather smug countenance. Some are elated and punch the air in triumph. Some mutter resignedly and wander off. One irascible individual reddens, stamps his foot and begins to rant semi-coherently. What single piece of paper could arouse such a wide range of emotion? The cover sheet.

As if Monday morning were not bad enough, you now face the prospect of losing your free period, in which you had planned to print out and copy a marvellous set of handouts for your Year 8s. In its place you will spend the best part of an hour in unfamiliar surroundings with little Johnny Herbert and the rest of his cronies in 3b.

Cover is the bane of any teacher’s life and can be a minefield for one who isn’t completely familiar with the routines of a school. It is best to be prepared.

When I was a PGCE student, one of my lecturers tried to persuade us all to carry an “emergency kit” for unexpected lessons, ie covers. This was to contain spare pens, pencils, felt tips, coloured pencils, rulers, erasers, paper, dictionaries and educational games which covered the full curriculum. As the year progressed various other items were added to the list: an inflatable globe, a Bunsen burner, a full set of the Encyclopaedia Britannica . . . While the sentiment behind this idea was undoubtedly sound, the practical considerations had, I fear, been overlooked. I had visions of turning up on the first day in my new post pulling a small trailer behind me.

In many schools, the idea is that the work is all set up so that all the cover teacher has to do is turn up, sit in the same room and get on with their marking. Unless you are doing a cover in your own faculty it is unlikely you will be expected to actually teach the lesson. That’s the theory anyway.

If you’re lucky you will arrive to find that someone else has made sure all the right books are there, that the students understand the work, that they all have pens, paper etc, and that they can get on quietly. Any potentially explosive groupings of students will have been split up. An unlucky cover will go a bit like this: You arrive, at last: you’ve had the devil’s own job finding the room.

You locate the scrappy bit of A4 on the teacher’s desk and spend a couple of minutes trying to decipher the scrawl on it. A screech attracts your attention and you raise your head to see Mandy Madam get a half-eaten packet of crisps out and empty the contents over Liam Lout’s head. The tone is set.

You attract their attention and gather them into some semblance of order while you explain the task. You pass out the textbooks, all 12 of them between the group of 28. After 27 voices shout “What page, Miss?” it strikes you that it would be a good idea to copy the instructions on to the whiteboard. You open the desk drawer, thankful that it’s not locked. You rifle a bit further and realise that this was just a moment of naive optimism. Reluctant to leave the class unsupervised, you wrack your brain for an alternative. You’ve spotted some prehistoric paper putty in the drawer so you write out the instructions and stick them to the board. Sorted.

Rather pleased with your inventiveness you sit down and reach for your marking. Liam Lout’s on the wander again. “My pen’s run out, Miss, I was trying to borrow one.” Don’t know why, he’s not likely to use it this lesson. You find him a pen. A few crumpled sheets of paper fly through the air, narrowly missing your left ear.

“Sir’s got our books, Miss.” You stifle the expletive. Well held. “He keeps them on the shelf in the stock cupboard, shall I get them out for you, Miss?” Nine lads bundle to the locked door. “Er no, I think there’s some file paper in the drawer.” Scrum averted.

You take the top off your red Biro and reach for the first of your Year 10 essays. Then: “I don’t get it, I wasn’t here last week.” “Just copy out the notes.”

Four seconds of peace before: “Finished, Miss.” “Start the next page.” “Did that yesterday day.” “Just hang on a minute while I find one of the subject staff.”

You write a note and send what looks to be the nearest thing to a trustworthy child to find the head of faculty - roughly equivalent to lobbing a bottle into the Pacific as it seems the whole science department has been kidnapped by pirates and transported to a distant island. Finally you breathe a sigh of relief and the coloured pen makes contact with the homework you wanted to give back this afternoon. It’s usually now that someone sticks their head round the door to see whether you’re all right. As they leave, you check your watch and notice you’ve got 17 seconds to collect up the textbooks before they all bolt for the door.

This is the way of cover lessons. If you try to fight it too hard you’ll end up with shoulders round your ears within minutes. Remain calm and settle for them doing the same. It could be worse, you could be out on the rugby pitch in the pelting rain without a jacket and only the fear of pneumonia to keep you company.

Lindsey Thomas teaches English at Lord Grey School, Bletchley TAKE COVER:YOUR BASIC KIT FOR COPING

* Try to be sufficiently ahead of yourself so that losing a free period isn’t a complete disaster * Have a couple of spare pens and some file paper handy * Locate someone you can call on if you need help * Read through the work set and send for more if it looks like they’re going to finish - ideally before they do * Take something to do, but don’t rely on getting it done