Digital watches
Assemblies were constantly ruined by interruption from digital watch alarms. The facilitator would lose his "flow", and if we had a guest speaker - illustrating for example the nativity story through the use of fuzzy felts - the shame on the school was too much to bear.

As an attempt to counter this, the headteacher introduced the following process:
At the start of assembly, anyone with a digital watch would get in a line to have their watch inspected by Mr Bridge. Mr Bridge taught computers, and understood modern technology. He would briefly examine the watch, stab randomly at its buttons, and then nod solemnly to the headteacher, confirming that any alarm had been deactivated.
Once this had taken place for every individual watch-owner, the assembly would commence and, without fail, at the turn of the hour a hundred alarms would go off at different pitches for about 5 minutes, while Mr Bridge stared shame-faced at his feet, and the headteacher slowly shook his head in disappointment.

Eventually, all wrist watches were sealed in a sound-proof tupperware box for the duration of assembly, following the day someone smuggled in a Casio SK-1 keyboard and, during the 9am cacophony, triggered a chipmunk-fast sample of "MrBridgeIsASlut".

edit: "keyboard" added for non-geeks/young people
( browser still relating boring anecdotes into a void on, Thu 20 Jun 2013, 13:00, 2 replies)

Mad for Skiing
The principal (American version of headmaster) of my elementary school was an avid skier. Growing up in the mountain west, this Wasn't uncommon. Several teachers shared his passion for sliding down steep hills with long sticks strapped to their feet. Every year we would have an assembly where this fellow brought his latest ski film and narrated it. The films were pretty awesome, but few of us kids were skiers. The assembly was more for the adults, made clear by their obvious enthusiasm for the event.

What we kids didn't really realize was how cool it really was to see pre-release, personally narrated versions of this guy's films:

www.skinet.com/warrenmiller/
(danalan Pretty good, for an amateur., Thu 20 Jun 2013, 4:26, Reply)

Guns and ammo
I was at primary school in the early to mid 80s, pre-Dunblane and (it seems) in a slightly more relaxed era of health and safety legislation. That must be how the deputy head got away with bringing a real handgun into assembly and firing blanks through a piece of card to show us that yes, even blanks in guns throw out detritus and are therefore dangerous too. It's a very important lesson to teach primary school kids. He also once set fire to a load of gunpowder in assembly to show that if it wasn't in an enclosed space, it just burns but it doesn't explode. See, I still remember this stuff. Job done.
(MonkeySpunkMoped, Thu 20 Jun 2013, 2:20, 4 replies)

Emily had a particularly chilly bum
Cool Ass Emily
(McChinaman banned, Wed 19 Jun 2013, 21:53, 1 reply)

Drumming
When I was about 8 or 9, I was quite excited to see a drum kit set up at the front of the hall one assembly. To this day I have no idea why, but one of the older kids had been given permission to play the drums in assembly.

The headmaster built it up to be something quite exciting and asked the boy what he would be playing.

'The theme from Dallas' came the proud response.

Now I don't know what the headmaster was expecting but even before he started playing I knew this was going to be awful. It was. 2 minutes of 8 beat and nothing else.

We never had live music in assembly again, which was probably a blessing.
(Inflatable Giraffe Punctureless since 1985, Wed 19 Jun 2013, 21:02, 2 replies)

The local donkey sanctuary down the way recently lost one of their livestock due to them getting the equine equivalent of a Deep Vein Thrombosis.
Needless to say, Gladys who runs the donkey sanctuary was devastated and blaming herself but the vet was able to reassure her saying that apparently 'Don't worry it's cool, ass emboli's are a big killer'.
( Amorous Badger NAKED BEA ARTHUR PHOTOS 4U, Wed 19 Jun 2013, 19:55, 6 replies)

Dead rock stars
Late-80s and our fantastic deputy head, Mr Vesey, was delivering his assembly. The theme was dead rock stars and he described how the likes of Janis Joplin, Jimmy Hendrix, John Bonham et al met their untimely ends.

He was particularly explicit, emphasising in great detail just how grotesque a vomit-asphyxiation death surely is. I believe the underlying message was 'Don't do drugs kids, that shit will fuck you up.'

I think the main problem with this bold approach to teaching issues of personal, social, and health education was that this was Primary School. I was seven. Mind you, to be fair I never did give heroin a go...
(Britpunk, Wed 19 Jun 2013, 19:32, 4 replies)

this one time jamie harvey picked a huge bogey and wiped it on becky greaves's back lol

( Je suis un vagabond is an unfunny, up your own arse middle class knob, Wed 19 Jun 2013, 15:57, 4 replies)

The overhead projector
The overhead projector played a key role in school assemblies. Nothing to do with retail accounting, the overhead projector, or "OHP" as the tech-savvy science teacher called it, was used to project text and images, written on transparent plastic film with felt tips, onto a screen at the front of the hall.
Responsibility for the OHP was not offered lightly. It involved removing the plastic documents and replacing them with new ones when asked, and also raising or lowering the height of the projector if necessary, adding or removing slim books to the pile on which the machine was placed, should the image not adequately align with the screen. This took initiative, and the OHP monitor would need to make necessary adjustments quickly and unobtrusively, so as not to disturb the rhythm of the assembly.
I was only trusted with the task once. Red haired and prone to allergies, an unexpected sneeze blasted strings and blobs of bogeys onto the machine, which were subsequently displayed to the hall 3 or 4 feet high in glorious 80s technicolor.
( browser still relating boring anecdotes into a void on, Wed 19 Jun 2013, 13:49, 3 replies)

During the quiet prayer bit in one of our primary school assemblies, there was a sudden crash from the back of the hall.
Turned out one of the girls was having a seizure, thrashing around and knocking chairs over. A teacher quietly went over but everyone else was told to shut up, face forward and carry on as if nothing was happening.

Years later she went to my high school and did the same thing again in one of our GCSE exams, the fucking selfish bitch. It really ruined my concentration.
( drimble he'd been white, he'd been black, Wed 19 Jun 2013, 13:06, 1 reply)

School assembly gone right, actually.
I went to a fairly scummy South London comprehensive, full of various diaspora from around those parts and as multicultural as only an inner city school can be. It was a well-meaning school overall, let down by the sheer amount of parents who simply refused to engage with their spawn and saw the secondary as a kind of nursery for teenagers. (Actually, they weren't always wrong, it did feel like that sometimes.)

Me being a socially inept teacher's pet, I queued quietly among a baying crowd of 13/14 year olds outside the converted lunch hall on a Wednesday morning, trying to calculate how to get into the hall last so I could be out of there sharpish at the end. We all filed in and I proceeded to stare at the clock for a while as the Head Of Year rabbited on about something or other. But a tension was filling the room; the normal bored mumbling had ceased and people were actually listening to the teacher. Confused, I tuned back in:

'... She was eight months pregnant, and they pushed her to the floor, forced a cattle prod into her vagina and shocked her with it until she passed out. The baby was later born prematurely and died. They did this because she wasn't married.'

Jesus. The teacher said vagina! There was a ripple of uncomfortable nudges in the hall about the phrasing, but it was clear that a sports hall full of teenagers from every year of the school had just been given the starkest depiction imaginable of human rights abuses available from a middle aged man with grey hair and ankle-swinger trousers. The silence was palpable, and all I could think about was some poor woman in Africa (I think, though I can't remember the rest of his story) being put through torture. Many of my classmates were from extremely religious countries themselves originally (Somalia, Palestine etc), was it really right to be raising something like that when opinions might differ at home? I maintain it was a bold move, but a good one.

I left the assembly intensely grateful for my own rights and freedoms and with a sense that the world was nowhere near as innocent as it was 45 minutes previously. Good job, Mr Whatever-Your-Name-Was. Good job.

(Additional: I am paraphrasing the story a little, but the details are there.)
( Bats, Wed 19 Jun 2013, 9:06, 3 replies)