Teachers at the highest-paying grade school district in the Chicago area make twice as much as their colleagues at the local elementary school paying the lowest wages, according to the 2009 Illinois School Report Card.
Oak Brook's Butler School District 53 paid an average $80,136 per teacher, compared with the $38,040 earned at Prairie Crossing Charter School in Grayslake.
Yet both suburban school systems boast strong student test scores, advanced courses and involved parents.
Does that mean teacher pay doesn't matter? The answer, like so many issues involving education, is not a simple one. A complex set of circumstances contribute to the salary gaps from one district to the next. Chief among them is the state's reliance on property taxes -- determined by a district's relative wealth -- to shoulder the bulk of education costs.
Researchers said Illinois' salary gap is one of the largest reported nationwide.
"Illinois is an unusual situation," said Jack Jennings, president of the Center on Education Policy. "You have great disparities in education spending, and therefore you have great disparities in teacher salaries."
But other factors also determine paychecks: a teacher's education level and years of classroom experience, the cost of living and the type of school district where a teacher works. High school districts traditionally pay more than elementary districts, and traditional public schools tend to pay more than charter schools.
School districts that can afford the most tend to have their pick of teachers. What's more, whether because of the top salaries or other perks -- such as time to plan lessons, rigorous course offerings or small class sizes -- the highest-paying districts tend to keep their teachers. They in turn cost more because salary schedules typically reward experience and advanced degrees.
"The districts with the higher salaries tend to get more experienced teachers and teachers with higher degrees, and they stay there," said Bob Shaevel, research director and benefit specialist with the Illinois Federation of Teachers.
Butler School District 53 proves the point. Nine of every 10 teachers in the west suburban district have an advanced degree. Teachers average 15 years of classroom experience. Many of Butler's 48 full-time educators will stay in the two-school district until they retire.
Superintendent Sandra Martin said the district tends to hire teachers with experience who are able to meet the expectations of students and parents who "want regular feedback."
"We want to be competitive because we want to retain the people we hire and train," Martin said.
Unlike most traditional public schools, Prairie Crossing Charter School relies on state money and fundraising. Charter schools typically do not collect local property taxes, but instead receive the state's share of per-student money that follows children from their local district to the charter.
School Director Myron Dagley said he tries to peg an incoming teacher's salary at about 90 percent of the pay at schools feeding the charter. He relies on the school's unique environmental mission and small class sizes to help with recruitment.
"(Teachers) have a lot of academic freedom implementing our curriculum," Dagley said. "We have a 2.4-acre campus. There are a large number of ponds, hiking trails, paths and prairie restoration areas. Our students, and teachers, have the benefit of accessing all those common areas."
Another factor in its relatively low average pay is that most of the school's 25 educators are young and do not have advanced degrees.
Despite large differences in pay, both Butler and Prairie Crossing report top scores with more than nine of every 10 students passing state assessments. Researchers caution against drawing quick conclusions about teacher pay and student performance, saying the relationship is difficult to measure.
Parental background and teacher quality tend to be the best predictors of how students fare in the classroom, said Mike Griffith, a senior policy analyst with the Education Commission of the States. The size of a paycheck doesn't necessarily translate to quality when so much depends on intangibles like how a teacher connects with kids or motivates families to get involved, Griffith said.
Still, districts with more financial resources typically have their pick of teachers.
"Do you have highly qualified teachers in every subject? Do you have people who are coming from top-tier education schools? Do you have people with advanced degrees? All those things can be controlled by how much you pay," Griffith said. "If you pay more, you have a greater ability to select the people you want."
Officials with Township High School District 113 in the North Shore said competition for top candidates is fierce. It had the highest average salary among high school districts last year, at $98,825, state records show.
District officials cite two statistics in explaining the sum: a third of all teachers at Highland Park and Deerfield high schools have more than two decades of classroom experience, and 89 percent hold at least a master's degree.
"Our responsibility to the community is to ensure we get the best teachers working with their children," said Sue Hebson, assistant superintendent for instruction and communication. "There's a competitive market out there for that."
Tara Malone is a Tribune reporter, and Darnell Little is a freelance reporter. firstname.lastname@example.org