It should be fast, intuitive and, most important, accessible from all of your favorite devices. But if you're reading Engadget, we suspect you're interested in some kind of digital equivalent: an app that can store those handwritten notes or, if you're ready to take the plunge, let you record everything with a keyboard or stylus. There's nothing wrong with relying solely on pen and paper (and if that's your preference, go for it!). The human brain, after all, can only store and retain so much information. Every student needs a good note-taking system.