It sounds like you aren't interested in class, those classes are so unbearable that you just drift away in your own thoughts. It happens to me a lot. Heres what works for me: Talking to friends before class, gettig enough sleep, and sometimes I just try to distract myself from daydreaming. Distracting yourself isn't going to directly help you focus though. Really, just get a glimpse of reality, get enough sleep, and talk to your friends about stuff, is what I'm trying to tell you here. This helps me stop daydreaming and focus on whatever you're learning.