Chicago Tribune reporter Diane Rado breaks down the Illinois Standards Achievement Test system and what it means for local schools. (Posted on: Oct. 31)

The push to toughen state exams for Illinois grade school students triggered widespread drops in 2013 scores, with hundreds of schools in some of the state's poorest communities seeing performances plunge, test results show.

But some schools in affluent suburbs — from Winnetka and Lake Forest to Hinsdale — saw far less severe declines. Even after the state made it harder to pass reading and math exams for third- through eighth-graders, those schools still posted some impressive results, a Tribune analysis found.

Chicago's top gifted and other selective-enrollment schools also posted extraordinarily high percentages of students passing the Illinois Standards Achievement Tests in 2013.

Even so, parents of some high achievers will be shocked by test results released Thursday as part of the annual School Report Card. The percentage of students in the ISAT's top performance category, "exceeds standards," dropped sharply. Many students accustomed to getting high scores dropped into the "meet standards" category, meaning they passed rather than excelled.

Overall, last spring's test results reflect a new reality in Illinois, where grade school scores were on the rise for more than a decade until the state raised the bar.

The state increased the scores required to pass ISAT math and reading tests by 13 to 30 points, depending on the test and grade, records show. The move caused tens of thousands more students to flunk and even some high-performing schools to drop in stature, according to the test results.

In 2012, 849 schools could brag that 90 percent or more of their students passed reading and math exams. In 2013 only 58 schools can say that.

Educators say that raising the bar has further exposed differences in how students perform at schools in wealthy communities compared with those in disadvantaged communities — a long-standing and hard-to-fix problem.

At Chicago's Robinson Elementary School, a pre-K to grade 3 school where 94 percent of children are poor, Principal Sonja Spiller brought in a retired teacher to help struggling students, arranged for after-school instruction and held a parent workshop.

Still, just 35.2 percent of her third-graders passed reading and math exams — a low performance but still a unique accomplishment. Robinson was the only grade school in the state to increase its passing rate in 2013, testing data show. The year before, only 29.9 percent of students passed those exams.

"It is a challenge, but we just say, 'This is what it is, and we have to push forward,'" Spiller said.

The School Report Card data include everything from test scores to finances and average class sizes at nearly 4,000 schools.

This year's report, officials said, is a revamped version designed to be more consumer-friendly. It includes information on advanced classes and athletic programs as well as awards for students and faculty.

The Tribune reviewed data for more than 3,000 grade schools that had scores for both 2012 and 2013 ISATs. It found that:

The percentage of third- through eighth-grade students who passed their ISAT reading and math exams fell by about 24 points.

The approximately 270 schools with the smallest declines, 12 percentage points or less, had lower percentages of poor and minority students as a group than average. Illinois' school population is 50.6 percent white and 49.9 percent low-income.

Schools with less than a 1 percentage point drop in passing rates were all Chicago schools that have high poverty rates but teach advanced students.

More than 700 schools with the largest declines in scores, 30 to almost 60 percentage point drops in passing rates, as a whole had higher percentages of low-income and minority students than the state average.

Education groups said the test results should prompt a new sense of urgency about fixing troubling gaps in achievement between advantaged and disadvantaged districts.

"Clearly, raising the academic bar reveals the gaps between rich and poor kids, and white kids and kids of color, and it raises fundamental questions about whether Illinois is funding schools in the right way," said Timothy Knowles, director of the University of Chicago Urban Education Institute.