Comment Using Khan as a supplement (Score 2) 575
I teach AP Chemistry and I know several of my students need all the help they can get. I created a class website, making sure to include several pages to the best quality chemistry podcast-type videos I could find. While Khan isn't perfect by any means, I find his videos to be an excellent backup explanation to the topics we discuss in class. I separated his videos into categories that reflect the different units we cover so its was easier for the kids to find a link that meets their needs. I know one of my seniors last year found his website invaluable to pass a college algebra class that switched teachers mid-year, leaving the kids without the best instructor. Sometimes it's nice to have a second voice explaining a topic (we even swap students for tutoring between teachers for this reason), so I think his efforts are on the right track. There are three sets which are of very good quality for AP Chem - the NMSI AP Chem videos, Khan, and a site called Chemguy.com. Even college students in their 100 and 200 level classes would benefit from his offerings.
One huge thing I have concerns about is the concept of the "flipped classroom" where kids are expected to go home and watch some online video and then expected to go into to class tomorrow well-versed on the topic and ready for some activity. Many higher-order topics need that interactive teacher-student discourse to full understand the topic. I've spent entire periods just covering a single free-response question, making sure to cover a number of tangential topics and showing the full spectrum of the question. Two guys named Bergmann and Sams are pushing the flipped classroom in the sciences, but haven't ponied up the numbers to show progress.
In an nutshell, Khan and anyone else who produces quality educational chemistry videos is a resource I will encourage my kids to use. I want it to help support discussion and learning in the classroom, but not replace it.