Alex Tabarrok explains why 15 minutes of his time has outweighed the rest of his teaching career:
In 2009, I gave a TED talk on the economics of growth. Since then my 15 minute talk has been watched nearly 700,000 times. That is far fewer views than the most-watched TED talk, Ken Robinson’s 2006 talk on how schools kill creativity, which has been watched some 26 million times. Nonetheless, the 15 minutes of teaching I did at TED dominates my entire teaching career: 700,000 views at 15 minutes each is equivalent to 175,000 student-hours of teaching, more than I have taught in my entire offline career.[1] Moreover, the ratio is likely to grow because my online views are increasing at a faster rate than my offline students.
Teaching students 30 at a time is expensive and becoming relatively more expensive. Teaching is becoming relatively more expensive for the same reason that butlers have become relatively more expensive–butler productivity increased more slowly than productivity in other fields, so wages for butlers rose even as their output stagnated; as a result, the opportunity cost of butlers increased. The productivity of teaching, measured in, say, kilobytes transmitted from teacher to student per unit of time, hasn’t increased much. As a result, the opportunity cost of teaching has increased, an example of what’s known as Baumol’s cost disease. Teaching has remained economic only because the value of each kilobyte transmitted has increased due to discoveries in (some) other fields. Online education, however, dramatically increases the productivity of teaching. As my experience with TED indicates, it’s now possible for a single professor to teach more students in an afternoon than was previously possible in a lifetime.
The counter-argument is that there is an ineffable quality of the classroom experience that raises its value well above the same material taught online. Even after many years of teaching, however, what exactly this quality might be remains ineffable to me. Actually, that is not quite fair. Bringing the most advanced students in any field up to the cutting edge of knowledge and beyond has always required a kind of apprenticeship rather than a more straightforward communication of data/knowledge. Fields with greater physicality, not just sports and dance, but also experimental biology, physics, and chemistry will also require more in-classroom teaching with greater attention from a human being. Even recognizing these exceptions, however, still leaves the vast majority of teaching open to massive productivity increases. Until late college, physics is mostly teaching knowledge known since Newton. Most of the mathematics known or needed by most people has not advanced much beyond Euclid and Pythagoras, let alone Euler. No one expects online education to substitute for apprenticing to a master, but much education at the college level is already mass education taught not by a master but by an adjunct.
