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)