So do I need to take notes?

I left my psychology class tonight baffled. My teacher showed us a film and it's main focus was, what we think we know we don't really know. The film was a threat to our history books because of some new evidence that was found that could possibly destroy the theory of how our country was founded. After the film the teacher continued to teach us the history of psychology and I began to wonder. "If the film you just showed us was an attempt to get us to question our belief of what we've been taught thus far through our history books, then why do you think we should believe your teaching"? It made sense to me. How do we trust anything these days? We are taught one way for so long and then someone comes by and says, "no that's not the way anymore this is the way". What's the point? Why do we need to know anyways? I wish things were simple. Praise God His ways are so simple.