The grey-haired teacher lines up pupils up in the playground and delivers a stern lecture about the complaints from neighbours that tennis balls have been thrown into their gardens during break.
"So," she concludes, "in future, all boys will write their names on their balls."
This is one of the real-life occurrences from Gareth Calway's 27-year career as an English teacher that have been incorporated into his first novel, River Deep Mountain High.
The book, which is being hyped by its publishers as "the first great comprehensive school novel", is peopled by characters he has encountered in the Welsh, Gloucestershire and Norfolk schools where he taught. There is the headteacher with no qualifications, the careers teacher whose entire working life has been spent at the school where she was a pupil, and the tramp who joined a one-day professional development course in order to escape the rain.
"It's 100 per cent true," said Mr Calway. "It's everything I've seen, thought and absorbed over the past 27 years. You couldn't make it up."
In many cases, the line between satire and verisimilitude is thin.
Pupils in Mr Calway's novel sit Statistically Wayward Attainment Tests, or Swats, set by the Ministry of Educational Statistics and Standardisation (Mess).
Meanwhile, the pressure of an impending school inspection forces two members of staff to speak to each other for the first time in 10 years, since a disagreement over a borrowed chair.
"I don't pull any punches," said Mr Calway, 52, who lives in Norfolk. "I hope it will tell parents what's really going on in schools.
"We're wasting an opportunity here with all this learning by numbers. Teachers are very committed. We should trust them to tell parents how children are doing, without relying on dodgy exams."
Since retiring last summer, he has already written two more novels: one for teenagers about the slave trade, and another telling a 1960s Cinderella story.
He now divides his time between writing, composing poetry, teaching drama workshops and exam marking. "Not only am I writing modern novels, I'm also examining on them," he said.
'River Deep Mountain High' is published by Bluechrome, pound;12.99.