SUNDAY I'm not worried. I taught for years at a prep school, so a week's supply in a state primary should be a doddle.
MONDAY I'm delayed by post-breakfast sandwich-making - a life skill in which I lack practice - and arrive at school flustered. I'm told to move my car and get strange looks when I ask where the coffee is. Not a good start. A multitude of Primary 6-ers troop in. Their verbal skills prove strangely limited: "The teacher lets us play", "The teacher lets us chat", "The teacher lets us eat". But I'm the teacher this week, I say, with gritted teeth. At 10pm, I make tomorrow's sandwich and put a mug and some coffee in my bag.
TUESDAY Spelling and maths all morning. I try to mark as I go along, but the queue lengthens and soon I'm the only person in the room who's doing any work. I tell the kids I'll mark their books later - "The teacher marks them now".
I work through lunchtime, sandwich in hand. At 3.30pm, after more class management and precious little teaching, I start marking again. One child has written nothing all day - how on earth did he slip through the net? An hour later, the janitor appears. "I'm locking up, love." Mine is the only car left in the car park.
WEDNESDAY The children look bemused when I set prep."The teacher calls it homework." I learn to say "playtime" and "language", instead of "breaktime" and "English". The phrase "I don't care what the teacher says" comes in handy. A colleague talks about baptism by fire, which makes me feel better and worse.
THURSDAY I have a sore throat and struggle to keep order, threatening tests and detentions. The kids suddenly fall silent and get on with their work. I haven't lost my touch after all. Then I spot the headmaster - I mean headteacher - at the back of the room. Later, as I gobble down my squashed cheese sandwich, I dream of prep school curries and toad-in-the-holes (or is it toads-in-the-hole? Too tired to care).
FRIDAY 3.30pm: The compulsory cohabitation is finally over as 30 restless children scramble for the door. I mark frantically, red pen versus the janitor. Some kids haven't understood a thing about fractions. Too bad. It's not my problem any more.
The words "Will you be a proper teacher one day?" ring in my ears as I depart. Tears prick my eyes. So much for 20 years' experience. You're only as good as your next lessonI PS. I Had a tuna roll for lunch today - highlight of my week.
Sue Rulli re used to teach in a Cambridge prep school. She now lives near Edinburgh