Findings from the City of Big Shoulders
Younger Students Learn More in Charter Schools

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The number of charter schools has grown very rapidly in the United States, from essentially none in 1990 to more than 3,400 today. Supporters believe that the flexibility granted these new public schools allows them to be more innovative and responsive to student needs than traditional public schools are. And the fact that no student attends a charter school unless his parents want to keep him there means that families can vote with their feet. When a parent leaves a charter, so does the funding associated with his child. Thus a charter school cannot survive without satisfied parents. But charter schools do not just answer to parents; they must also persuade an authorizer to recharter them every few years, and they must participate in statewide testing and accountability. Will this concoction of flexibility, answering to parents, and accountability to the government raise school quality? Bluntly put, do students in charter schools learn more than their counterparts in traditional public schools? More than they would have learned had they stayed put?

A Lottery-Based Evaluation of Charter Schools

Getting a reliable answer to these questions is vital to the current policy debate, but researchers who try to answer them face considerable obstacles. First and foremost, most charter schools are new and small. They just dont yet have enough results for researchers to draw conclusions. Second, although all charter schools share the features mentioned above, they are otherwise a diverse lot. Many set up shop in urban areas, serve minority and low-income students, and rely on a strategy and curriculum associated with an education management organization. However, some charter schools serve very rural, mostly white students. Some are run as start-ups by parent or community groups that do not associate themselves with a particular strategy or curriculum. Even within the world of education management organizations, approaches to learning can differ substantially. In short, an assessment of some charter schools is useful for learning about similar charter schools, but we should not expect it to inform us about all charter schools.

Even when researchers can evaluate charter schools that are large enough to contribute useful results to a study, old enough to have a track record, and representative of a substantial share of all charter schools, they face a daunting analytical challenge: finding students in the regular public schools who are truly comparable to the charter school students. Students who apply to attend charter schools are a self-selected group, and simply comparing them with all other students in local public schools is likely to be misleading. We do not even know whether to expect self-selection to work for or against charter schools. On the one hand, parents who try out charter schools may be especially motivated. On the other hand, parents whose children are doing well may avoid being guinea pigs in relatively untried schools.

In our study, we overcome this challenge by exploiting a feature common to most charter schools: the lottery that schools use to admit students when they have more applicants than spaces. Such lotteries present an opportunity, rare in education, to conduct randomized experiments of the type more commonly used in medical research.

We use this lottery-based approach to evaluate three schools managed by the Chicago Charter School Foundation (CCSF). Our treatment group (those who, in medicine, would receive the pill) comprises charter school applicants who drew a lottery number that earned them a place at one of the charter schools (lotteried in). Our control group (those who would receive the placebo) comprises the applicants who were lotteried out. All told, the study focuses on 2,448 students who are divided between the lotteried-in and lotteried-out groups. Its important to realize that all of the students in the study applied to charter schools, so self-selection is the same for all of them. All that distinguishes the groups is their randomly drawn lottery numbers, so we can be confident that the groups are comparable not only in observable ways (like race and income), but also in less tangible ways, such as motivation to succeed. Currently, we can compare the progress of both groups for up to four years following their application. We are continuing the study and will report further results as they become available.

Our results to date, which indicate clear positive effects of attending a charter school on the math and reading test scores of students who enter charter schools in kindergarten through 5th grade, represent the most credible evidence yet available on how charter schools affect student achievement. They are also uniquely informative for policymaking. In the long run, as charter schools become more established, almost all of their students will have entered in the early grades. Policymakers should therefore assign greater weight to studies that focus on such students than they do to studies that, because they lack experimental data, must focus on atypical students who enter charter schools when they are older.

The Chicago Charter School Foundation

Chicago is home to almost all the charter school students (8,817 of 9,980) in Illinois. Charter schools in Illinois are free to establish their own missions and curricula, but they participate in the state accountability system and must abide by personnel restrictions similar to those of regular public schools. In Chicago, charter schools receive a per-student fee equal to only 75 percent of the average per-pupil operating spending in traditional public schools. For the 200304 school year, it was $5,279.

The Chicago Charter School Foundation is a charitable organization that has been operating since 1997. It oversees five primary schools, one high school, and one K12 school. Together, its schools enroll more than half of Chicagos charter school students. Seats in the charter schools are in demand. In the spring of 2004, CCSF schools had 2.4 applicants for every student they could admit. Most CCSF schools are run by nonprofit education management organizations, but one is run by a for-profit organization.

Our current report relies on CCSFs oldest schools, all of which have been in operation since the late 1990s and have produced enough results to be evaluated: Longwood (K12), with 1,200 students in Washington Heights; Bucktown (K8), with 600 students in Logan Square; and Prairie (K8), with 350 students in Roseland. Longwood is run by Edison Schools, which is for-profit, while Bucktown and Prairie are operated by the nonprofit American Quality Schools. Although these education management organizations differ somewhat, their strategies are fairly typical of organizations geared toward urban, disadvantaged children. They feature a structured school day and curriculum, combined with a family-oriented approach designed to get parents involved.

The charter schools we study are all located in neighborhoods where the population is disproportionately minority and poor, but the schools are not alike. Longwood is in a very black neighborhood, and 99 percent of its students are black. Bucktown and Prairie are in neighborhoods that are mixed ethnically, but they draw students who are disproportionately likely to be Hispanic and in need of bilingual education (see Figures 1a through 1c).

The Impact of Charter Schools on Student Achievement