I think I would stay away from TK myself. While many would appreciate being able to make a gui, messing with TK and perl gets messy (and frustrating fast) - well for beginners anyway.
in reply to Perl High School
I really like the idea of a text adventure game. Especially considering you could create the more complex game engine yourself and let the students interface with it - thus allowing you to control the difficulty. Another reason, is that you can give the game a personality with little effort: basically they just have to change some text to give it some flavor. But then again I was sort of known for having smart ass input prompts, and error messages in my programs in college, so I'm partial to that sort of thing ;)