From TED site: "Salman Khan talks about how and why he created the remarkable Khan Academy, a carefully structured series of educational videos offering complete curricula in math and, now, other subjects. He shows the power of interactive exercises, and calls for teachers to consider flipping the traditional classroom script -- give students video lectures to watch at home, and do "homework" in the classroom with the teacher available to help."

You are interested in your math or science students using Khan Academy or doing some "Flipped Classroom" activities, you should watch the TED video above to see how you can use KA to suit your needs.