This comes to us via a tip from TwitÂter. The Khan AcadÂeÂmy has now postÂed on YouTube over 800 videos (find a comÂplete list here) that will teach stuÂdents the ins-and-outs of algeÂbra, geomÂeÂtry, trigonomÂeÂtry, calÂcuÂlus, staÂtisÂtics, finance, physics, ecoÂnomÂics and more. The clips have been recordÂed by Salman Khan, a HarÂvard BusiÂness School and MIT grad. And to give you a feel for them, we’ve postÂed above the first in a long sequence of lecÂtures on difÂferÂenÂtial equaÂtions. (The remainÂing lecÂtures can be found here.) This YouTube chanÂnel, which now appears on our list, IntelÂliÂgent YouTube Video ColÂlecÂtions, is one of sevÂerÂal video sites that proÂvide free online tutorÂing via video. As menÂtioned in the past, you can find online good video colÂlecÂtions dedÂiÂcatÂed to chemÂistry and calÂcuÂlus.