To be honest, I don't think teaching newbie Tk is a good idea.

:) sure it is, it depends on how you do it ( Re^3: Tkx Search for dialog box for text input , Re: TclTk interface with Perl code, is it possible? , Re^2: GUI toolkit+designer for the perl newbie , Re: Easier GUI )

if platform is Win$, using Wx coz Wxdesigner

If the platform is Mac/Linux/Win* use Wx coz of http://CitrusPerl.com/ and http://wxGlade.sf.net/my wxWidgets / wxPerl / wxGlade tutorial