Accountability, in most industries or professions, usually takes two forms. First and foremost, markets impose accountability: if people don’t choose the goods or services you’re offering, you go out of business. Second, high-performing companies develop internal accountability requirements keyed to market-based demands.

Public education lacks both kinds of accountability. It is essentially a government-run monopoly. Whether a school does well or poorly, it will get the students it needs to stay in business, because most kids have no other choice. And that, in turn, creates no incentive for better performance, greater efficiency, or more innovation—all things as necessary in public education as they are in any other field.

A full-scale transition from a government-run monopoly to a competitive marketplace won’t happen quickly. But that is no reason not to begin introducing more competition. Many middle-class families have plenty of choice (even beyond private schools): they can move to another neighborhood, or are well-connected enough to navigate the system. Those families who are least powerful, however, usually get one choice: their neighborhood school. That has to change.

In the lower grades, we should make sure that every student has at least one alternative—and preferably several—to her neighborhood school. We implemented this strategy by opening more than 100 charter schools in high-poverty communities. Tellingly, almost 40,000 families chose these new schools, and another 40,000 are on waiting lists. The traditional schools, as well as their employees and the unions, are screaming bloody murder, something vividly depicted in The Lottery, a recent documentary that shows community agitators brought in by the union to oppose giving public-school space to the Harlem Success network. But this kind of push-back is actually a good sign: it means that the monopolists are beginning to feel the effects of competition.

At the middle- and high-school levels, where students are more mobile, we can also create community-based choice systems, or even citywide choice systems. In New York City, for example, high-school students now have citywide choice (with some geographic priority), and schools know they have to recruit—and compete for—students.

To support effective choice, moreover, we need to provide real funding equity: the money must be for the child, not the school. So if Juan goes to PS 11, which gets $20,000 as a result, then that same $20,000 must go to a KIPP charter school if Juan decides to go there. Similarly, capital funds, or space within a school building, must also follow the child—either to PS 11 or to KIPP—on equitable terms.

Unfortunately, the likelihood of rapidly expanding choices remains small. Witness, for example, those 40,000 families wait-listed for charter schools in New York City. By the time the City opens another 100 schools to meet that demand, at least another 40,000 families will likely be waiting. And now that the union and its allies have seen the smashing impact of the first 100 charter schools, they won’t make it any easier to open the next 100.

That’s why internal accountability along the lines that Shanker discussed is critical. School districts need a system to fairly evaluate the effect of schools and teachers on kids, which is the best proxy we have for assessing “consumer preference” in a largely monopolistic system. Shanker also had the right idea about how to measure outcomes: by looking at student progress on apples-to-apples metrics, rather than at whether students do well or poorly against an absolute, static index. On a four-point scale, for example, a teacher deserves credit for moving a kid from a 1 to a 2 and should lose credit for letting another kid fall from a 4 to a 3, even though a 3 is better than a 2 in an absolute sense. Some kids come to school way ahead of others, and giving the school or teacher credit for that makes no sense. But if schools or teachers have essentially the same kids, with the same challenges, and the same starting performance levels, it’s pretty easy to measure which are helping the kids make progress and which aren’t.