Hi!
From my own experience, the following points come to my mind:

• Perl implements many concepts relevant to programming classes (references, regular expressions, threads e.g.)
• Perl can be used for other internet-related tasks besides cgi: parsing log files, processing XML, writing web robots etc.
• You might check out "Mastering Algorithms in Perl" ISBN 9781565923980 which has been reviewed on this site.

Good luck with your classes!