This occurred several months ago, but I am now ready to talk about it.
It was after lunch, and judging by the general lethargy, I must have been more soporific than usual. So I gave to a (normally exuberant) young man, seated in the back of the class, this note:
IN 30 SECONDS SCREAM WAKE UP!
Writing that now, I can see that its perhaps insufficient punctuation introduces some ambiguity. And then there’s always my scribbly all-caps penmanship, too. Anyway, thirty seconds passed. Grinning, he looked to me for confirmation; I smiled back and held my thumb aloft.
What happened next was a creaking, wordless wail. It sounded like a witch slowly opening a coffin. I mean, I had some indication of what to expect, and was still unsettled. Poe himself would have wept for mother.
It was obvious that the class had been frightened because not one of them stirred. (Speaking from broad experience, if a student causes a disturbance, it is rarely met without reaction.)
The shock wore off, and students turned round to see their (now) exuberant classmate and me laughing, high fiving, etc. This produced insistent objection, e.g. “No. No. Mr. Sipe, that was not funny.”
If this is where you’re asking what sort of demented person casually invents such distress, I assure you that I am following best practices. As it says in Why Don’t Students Like School? A Cognitive Scientist Answers Questions About How the Mind Words and What It Means for the Classroom:
We all inevitably lose the attention of our students… They will mentally check out. The good news is that it’s relatively easy to get them back. Change grabs attention, as you no doubt know.
And if you don’t know, now you know, Gentle Reader.