All of your reqirements are needed to write a simple OO module. So pick a simple spec, e.g., a Book class with title, author and ISBN as object attributes and number of books as a class attribute. In an hour, someone versed in OO Perl should be able to sketch out a solution.
Extra points for
- using strict and warnings without being told to
- using the two arg bless for inhertiance down the line
- encapsulation of class attributes (if you care about that sort of thing)
- Automating get/set methods with AUTOLOAD
- test script