This is not strictly a Perl question, but I know you'll be interested.
The class would probably be happier if I just gave them Code to Make PopUp Windows, Code To Detect Browsers and so on. But I'm determined to at least give them some idea of what's really happening, to understand what programming is, even if they're not really going to do it ever.
So, if you had six hours to do it in, and you were faced with a class who are at the level where they say "why do we need variables?", what would you attempt to cover?
I'm thinking Variables and Control Structures are the absolute fundamentals, but that's as far as I've got ...
($_='jjjuuusssttt annootthheer pppeeerrrlll haaaccckkeer')=~y/a-z//s;print;