From The Chicago Tribune: Demographic tweaks to a complex enrollment system intended to ensure diversity at Chicago’s best public high schools have created added anxiety for many parents who suddenly face tougher odds of getting their children into the elite schools. The changes aren’t as sweeping as last year, but nearly 100 city census tracts, more than 12 percent of the total, moved up in Chicago Public Schools’ four-tier system for ranking tracts based on socioeconomic factors that include median income. Twenty-one tracts climbed to the most prosperous tier 4, where students need excellent admissions scores, in some cases nearly perfect, to be accepted into the city’s elite selective enrollment high schools.