Chicago's public schools have performed abysmally for years on many measures. But that's how schools with overwhelmingly low-income enrollments typically do. On the Program for International Student Assessment in 2009, U.S. schools with small proportions of low-income students did as well as schools anywhere in the world—while American schools whose enrollments were more than 75 percent low-income scored like schools in developing countries.
In Chicago, low-income enrollments are the norm. Last year, an astonishing 85 percent of CPS students were from low-income families.
Why is the proportion of low-income CPS students as high as it is when the citywide proportion of low-income families with children under age 18 is a much lower 52 percent? Mainly because so many middle-class parents are unwilling to send their kids to the city's public schools. Instead, they send them to private schools, or, when their children reach school age (or high school age), they move to the suburbs.