A lot when I'm at school just because my professors post a lot of their content in our university's "database". I'm not about to print out all of it, so I look at it online. In addition to looking up extra practice problems, etc....
Probably like 3/4 of my day I spend 3 hours of school in publications, another hour or so for virtual Sociology, and after school I'm on my laptop most of the day because I have nothing else to do.