What's the recipe for good teaching?

The average teacher in Illinois received an average ACT score and went to an average college, a report on teacher quality released Wednesday by the Illinois Education Research Council found.

And while the report found that teachers with better academic backgrounds produce students with better test scores, some suburban principals argued there's no simple formula for determining what makes a good teacher.

"You're talking about people here," Naperville North Principal Ross Truemper said. "They can't be defined by a small number of quality indicators."

The study by the group from Southern Illinois University analyzed the academic background of every public school teacher in the state between 2001 and 2006, using an index of scholastic variables.

The index included teachers' high school ACT scores, the academic reputation of their undergraduate alma mater, whether they passed the Illinois basic skills test on the first try and whether they have proper certification.

The study found that the average ACT composite score of an Illinois teacher is 21. The state average for high school juniors last year was about 20.

And according to the study, the average Illinois teacher attended an undergraduate institution that Barron's, a college guide company, ranked as a 3 in competitiveness on a scale of one to six.

The study also found:

• Poor and minority students are the most likely to be taught by teachers with the weakest academic backgrounds.

• That gap is closing, as the Chicago Public Schools in the past five years significantly improved the academic background of their teaching staff.

• When the academic background of teachers improves, student achievement scores improve.

During the five-year period of the study, teachers at schools with the state's highest poverty levels made the greatest gains in academic capital, narrowing by 27 percent the gap between Chicago and the east central region of the state, where the educators with the highest academic index teach.

The gains were largely a result of hiring inexperienced teachers with stronger academic backgrounds, the study found.

George Olson, interim dean of the college of education at Roosevelt University, said city schools are following the lead of suburban schools, which have become increasingly stringent about the academic credentials of teachers.

"It used to be that the criteria for placing students in student teaching spots was minimal," Olson said. "They were going on our recommendation and students could go and do a modest to poor job and get hired. There wasn't a lot of scrutiny. It was based much more on their ability to perform in the classroom than expertise in content."

But some suburban principals say ACTs and GPAs aren't the determining factors in hiring.

"It's where you do your student teaching," Aurora District 129 spokesman Mike Chapin said.

In a competitive market, Chapin said, the references and contacts made during student teaching are what distinguish one qualified candidate from another.

"Grades are part of it, but there are a lot of people skills involved," Chapin said.

Truemper agreed that teacher academics should constitute just a piece of the hiring puzzle.

"We want to see that there's competency and that they value their education, but that's not a straight-A student necessarily," Truemper said. "You can't just be the most intelligent person in the world and expect to be a great teacher unless you have the skills to deliver that knowledge."

And suburban principals stressed that most local school officials don't have to choose between academic firepower and strong classroom skills.

The Maine Township schools often draw 100 candidates for every opening, Maine West High School Principal Audrey Haugan said.

"The grade part is what gets you in the door. Anything below a 3.0 would raise a red flag," she said.

But after that initial culling, teachers are chosen based on how they perform in the classroom and in a series of interviews, Haugan said.

"For us, it's how successful can you be in the classroom and how successful have you been in the classroom?" Haugan said. "You can be an excellent student and all, but not be able to reach kids at all."