The many big cities now looking for school superintendents—Houston, Las Vegas, Los Angeles, Newark, Seattle, and Washington, D.C., among them—need to pay attention to what has happened in Chicago. Like Chicago, these districts face big and persistent achievement gaps, with many troubled and low-performing schools. Unlike Chicago, they aren’t the one city in the country where students learn the most for every year they spend in school.
In the 31 years since being labeled by former Education Secretary William Bennett as America’s worst school system, Chicago has stopped hoping that some moralizing, a bit more teacher training, and a few more mandated courses will improve all schools. Instead, Chicago realized that different schools serve students with different needs...