My Take
Khan Academy is a great resource for students who need more review and a different mode of instruction.
How I Use It
I used Khan Academy with my student to give them the opportunity to practice new concepts, review previously learned concepts and extend their understanding of the lesson. My students were given the freedom to work on any concept that they felt comfortable with in order to gain confidence in mathematics. There was also assigned topics that student were required to work on for 20 to 30 minutes a week. The tracking mechanism made it easy to guide students through the tutorials.