That assumes that people who program the robots will be taught be human teachers which does not scale. If they are instead taught by robot teachers similar to Neal Stephenson's idea of A Young Lady's Illustrated Primer or a more advanced version of Khan Academy, then it will be very cheap to teach students. Kids are very good at teaching themselves if given the chance and the right materials: http://www.technologyreview.com/news/506466/given-tablets-bu...