Many on-line courses use frames. None that I have seen use frames well. Frames should be used to ease navigation through a web site, making top-level links constantly available to the user.
Few sites choose top-level links well.
Courses which use frames almost invariably offer links to a chat area, newsgroup, etc., using frames. What happens is that the user is left with a small window on their screen, which must always scroll through, containing the actual material. Usually, you want to go back through the contents of a particular frame. Click on your right mouse button and select 'back in frame' as an option.