A free online learning platform that magically instills you with concepts and knowledge in a matter of seconds from the comfort of your own room as opposed to a matter of semesters in a stinky classroom. Often chastised by teachers and professors for an alleged lack of interaction when in fact their actual contempt arises from Khan Academy's remarkable ability to underscore their incompetency.
Argh, I don't understand my calculus homework and I'm failing the class, argh.
*visits Khan Academy, watches 3 minute tutorial on indefinite integration*
*now an expert on indefinite integration, now has A+ in the class*