How I Use It
As a history teacher, the videos relevant to my content are limited, but the ones that are available and applicable are great learning tools. I have shown Khan Academy videos in my sixth grade classes and have also assigned them for homework. Usually, I assign or show Khan Academy videos to reinforce events that have already been covered in class, but occasionally, I use them as an introduction to a topic. The students like the informal feel of the presentations and the way that Sal Khan incorporates audio, visual notes, and other sources such as charts to keep things interesting; I like this variety because it appeals to multiple learning styles.
I find Khan Academy to be a very helpful and effective teaching tool because the presentations are so versatile. I like that I can show a video in class and then make it available to students outside of class so that they can access it and watch it repeatedly or review a short portion if need be. The only criticism I have is that there are very few history topics available at this point. I'm sure that there are more social studies presentations in the works, as the offerings on Khan Academy seem to expand by the day. Each teacher would probably use Khan Academy slightly differently, so I recommend reviewing the topics available for one's subject area and just viewing a few videos to see if it might be a good addition to your teaching toolbox.