A 9/6/10 article in the NYT talked about new research on study habits and retention of material. One is related to not using the same space to study. By moving locations (we think) the brain creates associations between background information and the information studied, thereby making it easier to recall the information.
Anecdotally, I've known this to be true for me, as I am often more focused and retain more info when I am away from my offices (home and work), on a plane or in an out of town hotel.
The 2nd retention notion is to vary the material that is studied in one sitting. If studying a foreign language, read, study vocabulary, practice speaking out loud. Apparently musicians have known this for years.
I have a couple of students right now who show me the notes they've taken on the chapter, and then when it comes to taking the quiz, their minds go blank. I may talk more with them about how they are studying the material.