in reply to
Design a Perl training day
... four people with various previous Perl experience ranging from none through "can write nice PHP web apps in Perl" to "can write useful tools in Cish Perl". Most of them have extensive experience with other languages ...
I think it is a bad idea to start with such an inhomogeneous group. It would probably be better to create different training days for different groups, depending on their level of experience.
You can lead your users to water, but alas, you cannot drown them.