Eight of 10 public high school juniors in Illinois weren't considered ready for college classes in all subjects based on ACT testing last spring -- and many students missed the mark even at posh suburban Chicago schools that graduate some of the state's brightest kids.

At Lake Forest, Deerfield, Northbrook and Hinsdale high schools, more than 40 percent of students didn't meet all four "college readiness benchmarks" -- ACT scores indicating they could do at least average in key freshman classes.

In Lincolnshire and Naperville, more than half of juniors scored too low to reach the targets in English, reading, science and math, though several hundred met three of four benchmarks, usually missing in science.

The Tribune calculated college readiness figures from student ACT scores released for the first time by the state under the Freedom of Information Act. They reveal a less-flattering picture of schools accustomed to high rankings and raise questions about the rigor of high school classes.

The readiness numbers generated skepticism and even heated criticism from some educators who questioned ACT's benchmarks, though schools were hard-pressed to explain why their students weren't considered prepared.

The nonprofit ACT company stands by its readiness scores: at least 18 in English, 21 in reading, 22 in math and 24 in science. The top possible score is 36.

Paul Weeks, an assistant vice president at ACT, said students who don't meet those scores may find themselves in remedial courses or struggling in regular college classes.

"I will hear a story about a student who maybe fell far short of one or two or three benchmarks and went on to college and did well," Weeks said. "But when we look across all the data, that is not the case."

School officials insisted that their graduates do, in fact, go off to college and do well -- though that information comes from student surveys and anecdotes.

At New Trier Township High School on the North Shore, 98 percent of graduates attend college, said Assistant Superintendent Paul Sally, who oversees curriculum. "We believe in our curriculum at all levels and believe it prepares kids for college," he said.

Still, about 38 percent of juniors fell short of meeting ACT readiness targets in all four subjects last spring. Conversely, about 62 percent of students met all benchmarks -- more than triple the state average.

"I suspect most parents would consider that number surprisingly low," said John Rekenthaler, parent of a New Trier senior. "I don't think 62 is a number New Trier wants to be associated with."

In Will County, between 25 percent and 35 percent of juniors in Lincoln-Way Community High School District 210 high schools met all readiness standards.

"Our reaction is, we have a pit in our stomach," said Sharon Michalak, who oversees curriculum and instruction and stressed the quality of district courses, teachers and student support programs.

At a college night last week at Lisle Senior High School, parent Wendy Nadeau was stunned to learn from the Tribune that 36 percent of the school's juniors met all benchmarks.

"That's kind of shocking," she said, adding that she expected a figure of at least 75 percent.

Another Lisle parent, Tim Hagen, also expected a higher figure, though he questioned whether the benchmarks are reliable given that so many students aren't meeting them.

School officials suggested that outdated state standards for high school students could play a role -- the state is working on new, more rigorous standards -- and that some students may not be enrolled in challenging courses.

High schools typically offer rigorous honors and Advanced Placement classes for top students, followed by regular classes and then lower-level classes for struggling students.