First, if you have your laptop open, it is almost impossible not to check email or briefly surf the Internet, even if you don’t mean to or have told yourself that you won’t. I have the same impulse if I have my laptop open in a meeting. The problem is that studies indicate that this kind of multitasking impairs learning; once we are on email/the web, we are no longer paying very good attention to what is happening in class.
A study that came out in June—and which got a lot of buzz in the mainstream press—suggests that taking notes by hand rather than typing them on a laptop improves comprehension of the material. While students taking notes on a laptop (and only taking notes—they were not allowed to multitask) wrote down more of the material covered in class, they were often typing what the instructor said verbatim, which seems to have led to less processing of the material. The students taking notes by hand had to do more synthesizing and condensing as they wrote because they could not get everything down. As a result, they learned the material better.* I think there is also something to the ease with which one can create visual connections on a handwritten page through arrows, flow charts, etc.