There, the GCSE history group are discussing World War II. A helpful student, one Tony Platinel, offers to bring in the wartime souvenir his builder father found recently while working on a nearby house.
The following morning, young Platinel turns up bright and early clutching his sports bag, and after registration trots off eagerly to find history teacher Graham Scrivener.
The bag is opened. Nestling within is a little bomb, some 18 inches long, with a neat set of fins. Mr Scrivener picks it up, and finds it suspiciously heavy. A horrible thought crosses his mind.
"Er, Tony," he remarks. "This seems not to have been detonated." A puzzled expression flits across the lad's features. "Sir, what's detonated?" he enquires.
While Mr Scrivener proceeds, gingerly, to carry the holdall to the dustbin store - mentally checking his insurance policies - the community policeman is contacted. He opines that yes, the item is an unexploded incendiary device and perhaps it would be an idea to evacuate the school. After all, these phosphorus devices are not at their most stable 50 years after being dropped, and are presumably even less user-friendly after being bounced into school over the shoulder of a 15-year-old.
So by 10am the building is empty apart from the police, bomb squad officers, and headteacher Andy Richardson, who feels duty bound to stay with his school. "For some reason I kept on thinking of some Norwegian ship's captain called Karlsen whose ship went down in the North Sea in the 1950s. I must have been singularly impressed by the pictures of him waving to the helicopter," muses Mr Richardson.
Forest Hill pupils are no doubt delighted by the whole event. Rather more surprising is the discovery that Mr Richardson, too, sees a positive side to the episode. "I've told Tony there's no need to feel contrite - he was doing something he thought was positive, and not to worry in the slightest. He was just trying to provide something stimulating for his history class. And the police told me they had never seen a building evacuated so fast and quietly, " says Mr R cheerfully.
Not even one tiny little down side? "Apparently once these things go up you can't put them out. They just go whoosh. We've got a few portable classrooms which could do with burning down. Perhaps I should ask him to bring in another one."
Potentially as explosive should have been the first sitting of the spanking new House of Commons select committee on education and employment, which had as its victim Sir Ron "The Fixer" Dearing for a grilling on his 16-19 review.
Observers were expecting fireworks when they spotted an animated conversation between Dr John Marks, a member of the School Curriculum and Assessment Authority, and Harry Greenway, Conservative member for Ealing.
Dr Marks, a man of fairly traditional views, is probably not flavour of the month within SCAA's Notting Hill bunker since publicly criticising the organisation's decision not to release separate scores in spelling, reading and writing last month.
Mr Greenway, a former deputy headteacher of strong views, was also held unlikely to be entirely happy with Sir Ron's suggestions for the future of qualifications, and in particular the "gold standard" A-level.
It looked as though Dr Marks might have been briefing the MP on particularly awkward questions which could be asked of his boss on A-levels. Breath was bated. But Mr Greenway's contribution, when it came, was surprisingly muted and Sir Ron sailed on serenely.
But speculation remains. Was the conversation between Dr Marks and Mr Greenway a simple discussion about the price of beef or other issues of the day? Are Sir Ron's fixing skills so elevated that he had nobbled every committee member? Or had he done Mr Greenway a favour in the dim and distant past?
Carborundum, as always, plumps for the innocent explanation that the protagonists were merely passing the time of day. But we are taking bets on whether, should the proposed merger of SCAA and the National Council for Vocational Qualifications go ahead with a shrunken committee, Dr Marks might find himself with - or without - a seat.
When is a four-year-old not a four-year-old? When an education officer heaves into view, apparently.
As ever, Carborundum is monitoring horrible educational jargon and a new and vile strain is being engendered by the nursery voucher scheme - quite apart from the argument as to whether it is politically correct to refer to pre-school. (Early years experts say it isn't, the implication being that nursery is inferior to school.) We digress. In Hampshire, lisping innocents barely out of nappies are henceforth to be known as "Pre-Year R" - that is, those in the year before reception class.
The county's policy officer, Shirley Goodwin, was suitably apologetic while voicing this aberration at a recent conference but even that was not enough to save her from a snort of "appalling" emanating from a headteacher in the audience.
Still, it could be worse. Elsewhere, in a horribly Orwellian phrase, the nation's crop of four-year-olds are described as being in Year Zero. What would they call those notorious infants apparently attending prep school in their nappies? Year Minus Two, perhaps?