Take them through Modern Perl. Or if that's too advanced, Learning Perl followed by Intermediate Perl.
I think that starting out with a lesson on use strict and use warnings is putting the cart before the horse. How would someone understand what strict 'vars', strict 'refs', and strict 'subs' without first learning about package versus lexical variables, about barewords, and about references? Don't teach people to include code they don't understand. Start with the basics and build up from there. If you want to discuss strict 'refs', you need to discuss symbolic and hard references. If you want to discuss strict 'vars', you need to discuss package global variables and lexical variables. Treat your students like grown ups and they'll rise to the occasion.