How I Use It
I used it, as a teacher, to see/learn alternative ways of presenting math material. I learned math one way and internalized as suited my learning style. Some of the Khan Academy videos presented material in a way that I would never have thought to teach it, had I not seen it here first.
* Set-up time is 5-15min only because I take the time to show my students the general layout of the website so they would be more successful at navigating it.
Khan Academy has a good thing going. Feedback from my struggling math students was that they liked being able to pause/review videos on specific classroom topics that they felt shaky on. The way the website was set-up made it clear to them how different sets of math knowledge/skills relied on and were connected to other sets.