Here are some links for the various popular learning theories. Also, if you Google 'learning theory' you will get more sites, but they will mainly fall into the same categories.
The problem people have when teaching a computer language or technical subject is the (false) assumption that all people learn the same way. It simply isn't true. Some people require a more active approach; others are adult-type learners that want actual problems and immediate gratification; many Perl coders are self-learners and you only have to show them the manual/pod, etc. From your description you are using more of an adult-learner approach and you are getting feedback that it is not working. My recommendation is that you stop doing that immediately. Walk over and take the materials away and tell your co-worker that you are going to help him/her using a different approach. Then research the different approaches and choose one that better matches your co-worker's learning style.
What happens if you don't do this? Your co-workers will likely hate
this language. They will probably also start to dislike you for foisting it upon them.
Lastly, I completely disagree with the use of log files for teaching elementary Perl. Simple data constructs, variable assignment, string manipulation, simple regexes, debugging and getting Perl installled/running are topics of primary importance because they must be used all the time. Parsing large files is not something you will do all of the time, and therefore should not be promoted too early any more than the use of sockets.
Celebrate Intellectual Diversity