Try both. I'm finding out that being a student is more or less a game and its one you can get better at. Take what you want to out of the material, but also figure out what the teacher thinks is important by looking at past tests or talking to students who've taken his/her class before.
Hope this helps.
__________________ Mind-Manual
"Pure hell forces action, but anything less can be endured with enough clever rationalization." - Tim Ferriss |