By contrast, private schools are thriving. (Just ask the members of Congress who fight against school vouchers but wouldn’t deign to send one of their own children to D.C.’s public schools.)

At least part of the success of private-school students can be attributed to the fact that private-school educators are held highly accountable for their job performance. They do not have long-term job security, they work on year-to-year contracts, and they are held accountable by annual job evaluations.

Private-school teachers work harder because they have to. In public schools, by contrast, powerful teachers unions have secured long-term tenure for the teachers, thus removing a powerful mechanism for professional accountability.

In effect, America’s public school system functions as a monopoly. As with all monopolies, there is no incentive to change. Even as the economy continues to tank, public-school teachers know that they are virtually immune from termination. Their annual evaluations are meaningless because they have tenure. Predictably, many public-school teachers do just enough — sometimes barely — to not get kicked out.

But could you imagine how much more engaged public-school teachers would be if their jobs were actually on the line — especially with this economy? Holding public-school teachers accountable for their performance could kick-start a revolution.