I just found an excellent article by Mark Kleiman called Unbalanced growth and educational technology. It makes an interesting point about teacher pay, from a non-obvious starting point.

Thirty-five years ago, William Baumol thought about why the price of orchestra tickets keeps rising, even compared to other prices or to wages. (Citations here.) His answer: while most of the economy enjoys productivity gains, live music performance doesn’t: “Any attempt to produce a half-hour string quartet with less than two musician-hours of effort would meet with resistance.” Therefore, the price of live music must rise compared to the prices of other things, or the wages of musicians fall compared to other wages.

Now think about the application of that principle to education. If the fundamental instructional technology for K-12 schooling remains one teacher writing on a blackboard in front of a class of thirty students, then the relative cost of education will rise without limit.

The response from Steve Teles is, if anything, even more pointed than Kleiman’s original.