No, I think you have it right. I thought of a unit study as just studying some topic in depth. FOr instance, you might do a unit study on WWII. You'd read non-fiction books, historical fiction books, perhaps incorporate some writing....as opposed to having a textbook and moving superficially from one topic to the next.

Well, my current understanding of unit study is that you'd study WWII but it would encompass history, math, science, geography, social studies, art, music, and probably PE lol.

I guess it's a bit like FIAR where using one book you do math, science, social studies, geography, lit study, art.