I have gone on to a three-day week. After eight years full-time as an itinerant three-subject teacher in a state comprehensive, the time has come to exchange about pound;9,000 in salary for an “I do not have to put up with this hideous lifestyle” exercise.

If you are a teacher with your own classroom, a resources cupboard or a filing cabinet, or just somewhere to leave your coat and lunchbox - this article is not for you. No, this is for those unsung heroes who carry their life round in large coloured plastic crates. It is for those tortured souls who never do the same thing twice, being at the mercy of constant curriculum change within their subject bundle, for those victims made to teach science in a music room, art in a dining hall and, worst of all, design and technology in any circumstances.

I refer not to supply staff but to the timetable hole-fillers, the multi-subject men and women - the box-people.

The days of “cookery afternoon” or “woodwork and metalwork morning” are gone. Now it’s all neat one-hour slots in which, in theory, children can build skills and knowledge, seamlessly moving through French verbs, quadratic equations and pizza toppings - punctuated by registration sessions and then on the bus.

But for the flexi-teacher, the cardinal sin in a cash-starved comprehensive is to “lose” resources during science and technology lessons - so don’t let lessons get in the way. They are a sign of weakness.

Scientific processes do not understand bells or nomadic box-people so it is easier to throw it all away and put it down to“experience”. The box feels heavier, the first signs of box fatigue.

By now there is slippage between where one is and where one is supposed to be; in schools it is perceived wisdom that everybody is instantaneously in position. Box-people fail in the great scramble for credibility because of these plastic albatrosses.

After another series of steps, fire doors, on-coming hordes and maybe 100 yards of footslog, you arrive at the graveyard of traditional teaching and learning - the IT room. Place the box on top of the scanner, the latter is not working anyway and hasn’t for weeks - this is IT, remember.

The printer and passwords will not work, the sun is effectively blanking out three screens and everybody needs help. You are expected to firefight computer problems the moment you enter the room, - and teaching is an anathema to people who want to stare at screens and play with little moving arrows, so you are trying to draw their attention to the fact that “I want to teach you something”.

Computers are clever. But they don’t understand schools and always crash at bell-time when you want to start your journey. Just press reset and get on your way - what’s lost is lost, which is usually everything.

To a box-person the destination does not matter, the journey does.

Keep “floating” in that classroom with one eye on the clock and the other on the door, don’t get involved with anything, it will drag you down when you have to move on. Above all, love your box - however heavy it becomes.

Phil Harley teaches part-time in a Midlands comprehensive school. He lives out of a box