What kind of product would work to provide a feature on a school website to allow teachers to post homework assignments and allow students / parents to quickly find the assignments by class and subject? I'm thinking wiki or cms but they don't seem to hit the mark completely. FYI I have VPS hosting so I can install whatever I want.
I have used moodle for a while, it is an open-source CMS that should provide all that you need.
You may be able to use Wordpress with Buddypress and a plugin like this courseware one.