You don't have to be teaching for long to forget what it feels like to be on the other side. Very quickly the classroom becomes your domain. You decide what happens there; what work will be done; how people behave. Your charges can't even answer a call of nature without your say-so.
All right, so these days students are officially allowed a "voice", but you only have to watch them being shepherded about the place during college induction week to realise the loss of liberty that signing up for a course involves.
So it can be a salutary experience for a teacher at any stage of his or her career to have to give up some of their power to others. And you don't even need to join a class yourself to do so. All it takes is to walk in through the doors of a hospital.
In my case, I was more a potential patient than a real one. In order to diagnose my elusive condition, my doctor had decided I needed to be subject to every test known to medical science. Today it was the turn of the CT scan.
"Take a seat," said the nurse as I arrived, looking a little lost, at the diagnostic unit. I sat there for ten or 15 minutes. Nothing happened. Luckily, I had brought my marking with me. Then the nurse came back with what looked like a litre of white emulsion paint in a plastic bottle. "Drink this at 15-minute intervals," she said, putting a beaker down beside me. No explanation as to why I should drink it, I noted.
It tasted like emulsion paint, too. After two doses - and an essay and a half decorated with red pen - the nurse reappeared. "We'll need to do better than that," she said, pointing at the remaining liquid. I glanced around me. Was there a congenital idiot in the room? It seemed not, so I assumed she must be talking to me.
"You didn't tell me how much I should drink in each dose," I said, as pleasantly as I could muster. "Now you just drink it down and stop being so cheeky," she said. Cheeky? I must have been 12 years old when I was last called "cheeky". Was she speaking like this because I was a patient? Or was it simply that I'd had the temerity to cling on to life beyond the age of 55 and thus become an irrelevance?
When she next came back - another two essays further on - the contents of the bottle had been fully transferred to my insides. "Haven't you done well?" said NHS nurse of the year. Mindful of the posters warning of the consequences of assaults on staff, cheeky-boy just about managed not to wring her neck.
She led me to a cubicle and handed me a gown. I couldn't help but notice how skimpy it was - more like a scrap of cloth than a garment. It also had the usual hospital opening at the rear, so that you could show your bottom off to whoever might care to look. "You can leave your shoes and socks on if you like," she said, handing over a plastic bag. "The rest of your clothes go in here."
Standing there in my mini-skirt, hairy legs and clumpy shoes sticking out beneath, my clothes wrapped up in a plastic parcel under my arm, I finally understood the phrase "death of dignity". As best I could, I clutched the two sides of the gown together behind my back. After all, there are more ways than one of being cheeky.
Mercifully, at this point I was handed over to the technician who was to conduct the scan itself. She seemed to consider that I might have at least half a brain, and actually explained what was about to happen to me.
Back in the classroom the next morning, I made a particular point of outlining in detail exactly what we were going to do and why. When a student asked a question, I didn't accuse him of being cheeky either. And at least all their homework had been marked.