In a three-part computer-assisted investigation Catalyst reveals that, as "Chicago's public high schools have become a system of choice, ... high schools in high-poverty neighborhood ... are left with predominantly low-achieving kids and a disproportionate share of special education students." In the first part Duffrin analyses school-board data, and concludes that schools left behind have hard time attracting good students and teachers. As a result, their average test scores have been dropping over the years. In the second part the reporter focuses on one school's decline, and on its attempts to recover. The third part "explains why parents and students avoid certain schools."