What Charter Schools Can Teach the Rest of K-12 Education

If you're interested in how K-12 schools might improve their performance, charter schools can be viewed as a laboratory experiment. Sarah Cohodes discusses the lessons they have to teach in "Charter Schools and the Achievement Gap," written as a Policy Issue paper for Future of Children (Winter 2018). From a social science view, charter schools have two especially useful properties: there are enough of them to have a reasonable sample size, and a number of them are required to admit students through a lottery process--which means that those randomly selected to attend the charter can be compared with those randomly not selected to do so. Cohodes notes:

"The first charter schools were created in Minnesota in 1993. Forty-three states and Washington, DC, now have laws that permit the operation of charter schools, and around 7,000 charter schools now serve more than 5 percent of students in the United States.1 They’ve grown steadily over the past 10 years, adding about 300 or 400 schools each year. To put this in perspective, about 10 percent of US students attend a private school, and 3 percent are homeschooled. ...

"Because charter schools are required by law to admit students by a random lottery if they’re oversubscribed, charter school admissions are analogous to an experiment in which participants are randomly assigned to a treatment group or a control group (a randomized controlled trial). After accounting for important details that arise from operating a lottery in the real world versus doing so purely for research purposes, such as sibling preferences and late applicants, a random lottery assigns the seats for charter schools that are oversubscribed. This allows researchers to compare the outcomes of a treatment group of students who were offered a seat in the lottery to a control group of those who were not."

Of course, it's also possible to study the effects of attending charter schools by finding a good comparison group outside the school, in what is called an "observational" study, but choosing an  appropriate comparison group necessarily adds an element of uncertainty. The research on charter schools finds that on average, they perform about the same as K-12 schools. But charter schools  vary considerably: some do worse than K-12 schools, but some do better.

"The best estimates find that attending a charter school has no impact compared to attending a traditional public school. That might surprise you if you were expecting negative or positive impacts based on the political debate around charter schools. But using both lottery-based and observational estimates of charter school effectiveness in samples that include a diverse group of charter schools, the evidence shows, on average, no difference between students who attend a charter and those who attend a traditional public school. However, much of the same research also finds that a subset of charter schools has significant positive impacts on student outcomes. These are typically urban charter schools serving minority and low-income students that use a no excuses curriculum."

 Here's how the "no escuses approach" is defined in a couple of the lottery-based studies:

"In Massachusetts, school leaders were asked whether their school used the no excuses approach, and schools that did so tended to have better results. The study also drilled down to examine specific practices associated with no excuses. It found that a focus on discipline, uniforms, and student participation all predicted positive school impacts, with the important caveat that no excuses policies are often implemented together, so that it’s difficult to separate the correlations for individual characteristics.

"The New York City study aggregated school characteristics into practice inputs and resource inputs. The practice inputs followed no excuses tenets: intensive teacher observation and training, data-driven instruction, increased instructional time, intensive tutoring, and a culture of high expectations. The resource inputs were more traditional things like per-pupil-spending and student-teacher ratios. The study found that the each of the five practice inputs, even when controlling for the others, positively correlated with better charter school effectiveness; the resource inputs did not."

Cohodes offers an overview of the empirical studies on charter schools. Of course, such studies need to take into account possibilities like whether better-qualified students are applying to charters in the first place, or whether charters may benefit from using disciplinary or suspension policies not allowed in other schools, and so on. But here's a bottom line:

"Attending an urban, high-quality charter school can have transformative effects on individual students’ lives. Three years attending one of these high-performing charter schools produces test-score gains about the size of the black-white test-score gap. The best evidence we have so far suggests that these test-score gains will translate into beneficial effects on outcomes like college-going, teen pregnancy, and incarceration. Given the large and potentially longer-term effects, the most effective charter schools appear to hold promise as a way to reduce achievement gaps."

If swallowing the entire "no excuses" approach is too much, the one practice that seems most important to me is intensive tutoring, so that students don't fall so far behind that they lose touch with the classroom. She writes:

"One charter school practice stood out: high-quality tutoring. Many high-quality charter schools require intensive tutoring as a means of remediation and learning, often incorporating one-on-one or small group tutoring into the school day rather than as an add-on or optional activity. ... As a strategy to close achievement gaps, adopting intensive tutoring beyond the charter sector may be less controversial than focusing explicitly on charter schools."

There are both direct and indirect lessons from charter schools. Cohodes focuses on the direct lessons: a "no excuses" approach that includes intensive tutoring. The indirect lesson is that it's useful to have experimentation in how K-12 education is provided, and then to have those experiments evaluated rigorously, so that productive ideas have a better chance to spread.

Readers interested in more on lessons from charter schools might start with "The Journey to Becoming a School Reformer" (February 13, 2015), which describes how Roland Fryer, an economist and school reformer, first sought to figure out the key elements of charter school success and then to apply them in public schools in Houston and elsewhere. Also, Julia Chabrier, Sarah Cohodes, and Philip Oreopoulos offer a discussion of "What Can We Learn from Charter School Lotteries?" in the Summer 2016 issue of the Journal of Economic Perspectives (30:3, 57-84).