Yeah, but those books use steep vocab that nobody likes. And besides you got to throw into account the variable that is bias. Personally, when I learn stuff in school, I just go with the flow and learn on whatever the teacher tells me. After we have the quiz or test though, I then go on wikipedia or watch History Channel specials on it. That's how I deal with material of that nature.
Stop going on Video Game Sites when you should be studying! Nah jk - if you are curious enough about something, wikipedia it. But since you're studying for a test, I would just study what's in the book. The teacher can't ask you any quenstions on a subject that's not discussed in the book or in the lectures.