What’s behind gap between scores on ISAT, ITBS

In mid-May, the Chicago Board of Education released math test results that put Chicago within striking distance of the national average. Those scores are in stark contrast to a dismal showing on a state math test administered in February.

This spring, 45 percent of 8th-graders scored at or above the national norms on the Iowa Tests of Basic Skills (ITBS). That’s a mere 5 percentage points below the national norm of 50 percent.

Meanwhile, on the Illinois Standards Achievement Tests (ISAT), only 20 percent of Chicago’s 8th-graders received passing scores in math, compared with 47 percent for the state as a whole, including Chicago.

Math scores for the two other grades that took both tests—3rd and 5th—showed similar gaps.

For math, ISAT is a tougher test than the ITBS, according to a company that designs review materials. The state test focuses almost solely on concepts and complex word problems. Such challenging material comprises only 30 percent of the ITBS, which is mainly computation and simple word problems, explains Carole Shulman of Educational Design.

Weaker reading skills might explain why Chicago students underperformed on the state math test, says Barbara Radner of DePaul University. “Every kid who has a reading problem is going to have a math problem if you’re dealing with word problems,” she notes.

Schools also devoted less energy reviewing for the ISAT than they did for the ITBS, which is central to student retention and school probation, she adds. “All the preparation in the elementary school is for the ITBS, with few exceptions,” she notes.

The two reading tests also differ, with the ISAT having fewer and longer passages. However, Chicago students’ scores on these tests were closer and, in some cases, higher on the ISAT than on the ITBS. For instance, 28 percent of 3rd-graders met national norms on the ITBS, compared to 33 percent who met or exceeded state standards on the ISAT.

That means that a passing grade on the state reading test is on par with the national norm, observes Timothy Shanahan of the Center for Literacy at the University of Illinois at Chicago. “Essentially, what you’re seeing is that kids who hit these ‘new, higher standards’ [in reading] are at about the 50th percentile,” he continues. “That means these world-class standards are pretty much the average.”