10am: Am in ER. Unfortunately, not the TV hospital drama with George Clooney, but the Exclusion Room, the school's dumping ground for badly behaved pupils. It is more like Cell Block H, without the Australian accents. There are no windows and it reeks of damp. Four inmates are currently ensconced in dimly lit, dismal booths. They are supposed to be getting on with work set for them by their subject teachers. Three are at least attempting to work, but the fourth is staring at the ceiling and sighing.
"I'm bored," he informs the ceiling. The other pupils wriggle a bit behind their wooden partitions and snicker quietly. The phone rings and I answer it.
"Is Elliot Jenkins with you?"
I check my list. "No," I reply.
"Are you sure? Tall boy, wears signet rings over black gloves, even in summer. Refuses to take his coat off."
I look at the children in front of me: two girls and two small, scrawny-looking boys. He's definitely not here, unless he is a master of disguise.
"No," I repeat.
"Oh dear," she sighs, and hangs up. Ten minutes later the door opens, admitting a male PE teacher and a large, truculent teenager sporting tracksuit bottoms and a black anorak zipped up to the neck. He has no bag, but is clutching a chewed biro between his begloved fingers. Enormous gold signet rings twinkle in the half-light.
"Elliot Jenkins, I presume?" I ask with a slight smile. The boy ignores me and glares at the floor.
"I found him wandering around the corridor," says the teacher, flashing me a sympathetic grin. "Sit over there, Elliot." He points to a desk at the end of the row of secluded desks. "Take your coat off."
"No," grunts Elliot, and puts his arms and head on the desk. The teacher whispers to me: "If he stays like that for the rest of the hour, that's fine. Let him. If he starts to cause trouble or leaves the room, call reception immediately. Oh, and watch your handbag; he's got a reputation for thieving phones, too." With that, he leaves.
I put a copy of An Inspector Calls on Elliot's desk, with some file paper and a typed list of questions relating to Act I. He pushes them all off the desk and continues to sit there with his head on his arms.
"All right, Elliot, what's occurring?" asks the bored boy.
"Piss off you freak," replies Elliot, and we all get the message that Elliot isn't in the mood for idle chit-chat.
Thankfully, after 30 minutes, the bell rings for break and I am released back into the community.
11am: In the sanctuary of an ultra-modern staffroom I eavesdrop on a conversation taking place next to me.
"So she just walked out then?"
"Yes! She left the class by themselves in the middle of the lesson and said she'd had enough!"
"Which class was it again?"
"But they're a good class!"
"I know! Just as well, too - if it had been 10JCT the lab would have been wrecked."
"Well, the kids said that she came in, told them to get on with their work and not to bother her. She put her feet up on the desk and started reading a copy of Nuts! Then when one of them asked for some help, she screamed at them and walked out!"
"You do get some odd supply teachers, mind."
"Yeah, do you remember the one who used to practise her golf swing at the back of the art room?"
"That's right! And swigged vodka out of the turps bottle?"
"Yeah ..." They then both notice that I am listening and start talking about Year 9 target grades.
12pm: Am covering a design and technology class. Year 7 are supposed to be designing mouse mats to celebrate the forthcoming Olympic Games.
"What do you think of my mouse mat, Miss?" I am confronted by a sweet-faced boy proudly showing me a detailed picture of a decapitated head, complete with staring eyes and gory locks.
"How do you know what a severed head looks like?" I ask with mounting trepidation.
"Done it in history, Miss," he replies airily. "Henry VIII had two of his wives beheaded and Sir said you could bribe the executioner to sharpen his blade so that it would only take one go. Otherwise they might hack you about with two or three blows."
Am feeling quite ill by this stage and usher the bloodthirsty cherub back to his seat. Not sure how he got from the 2012 Olympics to severed heads, but then when you look at the violent PlayStation games they've got, I shouldn't be surprised.
3pm: In the staffroom, gossip is rife about a pupil having thrown a chair at one of the history teachers. "Well, surely they'll have to exclude him now," says someone.
"I thought he was in ER."
"I thought they nailed the chairs down in ER."
"How's Jack?" (the unfortunate history teacher)
"Oh, he's OK. He had the sense to duck."
"And this pupil's name is?" I ask tentatively.
"Elliot Jenkins," they chorus.
Jo West is a supply teacher based in Cardiff. All names have been changed.