High turnover also places a staggering burden on taxpayers by consuming resources that otherwise could be devoted to books, tutors and other instructional resources.

The Texas Center for Educational Research pegs a district's total turnover cost per teacher — for paperwork, temporary workers, productivity losses and hiring and training a replacement — at about 150 percent of the departing employee's annual salary.

Seattle and other urban districts are trying several strategies to reduce teacher turnover: Philadelphia and New York conduct exit interviews, and Seattle will start exit surveys this month.

Denver and Seattle both signed contracts in 2004 with their teachers that offer the prospect of bonuses to highly qualified teachers who commit to working in a high-poverty school.

But because many districts, including Seattle, do not track teacher turnover routinely, it is hard to demonstrate whether their strategies are addressing the problem. Many districts also don't regard teacher transfers within a district as turnover, but education researchers argue that the effect from a school's perspective is the same as if the teachers left the district. (All subsequent references to turnover in this story include teacher transfers within a district.)

"Always starting over"

"If you have people in and out, in and out, in and out, you're always starting over," McMillian said. "It's not fun."

But McMillian, who is in her fifth year at High Point's helm, also believes that the school now has strong, committed teachers. A new union contract protects her staff, she says, from the kind of displacements triggered by four years of declining enrollment.

Kacey Guin, a researcher at the University of Washington's Center for Reinventing Public Education, says districts may be pouring money into training teachers without an effective way to keep them in schools with high needs.

The average Seattle elementary school loses one out of five teachers each year, Guin found from analyzing state records from 1996 to 2002. (Her published study didn't identify the district, but The Seattle Times verified independently that it was Seattle Public Schools.)

That's slightly higher than the national average, said Richard Ingersoll, a leading expert at the University of Pennsylvania on teacher turnover.

Though some policymakers believe that retirements largely explain turnover, 7,000 teachers in a national survey pointed far more frequently to job dissatisfaction or career change as the main reason for their departures.

"And often those are your best people," said Ingersoll, a former high-school teacher.

Imbalance in experience

In Seattle, the annual turnover rate has ranged from 7 percent at Whittier Elementary in the North End to 35 percent at Madrona K-8 in the Central Area. Maple and Leschi elementaries, South and Central Area schools where about two-thirds of students are poor, notably had below-average turnover rates of about 12 percent.

Pat Sander, an elementary-education director and former principal, says turnover is not always a bad thing: "You want the idealism that new teachers bring, and you want the experience level that veterans bring."

In some schools, that balance doesn't exist.

The state's Web site shows at High Point last year the "average years of teacher experience" was 5.8. That figure fails to show a huge imbalance: About half of High Point's 14 teachers had three years or less of experience, district records show. Only one teacher had more than 20 years' experience.

Dissecting teachers' experience levels in this way, as Denver Public Schools does, is far more useful to parents because the numbers represent actual teachers rather than an imaginary figure, Ingersoll says.

Teacher burnout

It's not just novices who abandon ship. Plenty of seasoned teachers get burned out by the intensity of their workweeks.

Teresa Alsept had worked for a decade in high-poverty schools when she transferred from Meany to Eckstein Middle School — a Northeast Seattle school that, by comparison, has about 80 percent fewer poor students.

At Meany, Alsept says it became wearisome trying to motivate her students and cover all the material within the year. Many families were hard-pressed to provide their children with food, clothing and shelter, much less participate in their education, she acknowledges.

As Alsept learned of the challenges some of her Meany students faced, she fretted about how to deal with their unruly or apathetic behavior: Do I give them some slack or do I hold them to the same high standard as everyone else?

"That's the part that doesn't always get talked about," she said. "We have awesome parents at Eckstein who have high expectations for their kids and their kids know it."

The district could enable more parents to get involved by operating more neighborhood-based schools, Alsept said. While only about half of Meany's students live in its region, at Eckstein nearly all students do.

Effect of enrollment, layoffs

Both layoffs and enrollment dips trigger union-contract provisions that hurt teachers with the least seniority. The Seattle district laid off 178 teachers at the end of the 2002-03 year to close a budget deficit.

At the same time, Meany saw its enrollment plunge nearly 20 percent by the fall of 2003. It was the least-popular choice among entering sixth-grade students. Eckstein's enrollment dipped 0.8 percent over the same period, and it was the most-popular choice among middle schools.

Thus Meany's teaching staff began the 2003-04 year with 10 new faces, compared to eight at Eckstein.

But the turnover represented one-third of Meany's teaching staff, compared with only 14 percent of Eckstein's. School size accounts for the difference: Meany, with 467 students this year, is the district's smallest middle school. Eckstein, the largest middle school, enrolls 1,247.

Retention incentives

Bonuses and more job security are major features of new contract with the Seattle Education Association that Superintendent Raj Manhas touts as an antidote to teacher turnover.

Several national experts like Ingersoll say that improving working conditions in high-poverty schools, especially for new teachers, would be more effective than a bonus of a couple thousand dollars. But 42 percent of 1,942 new Washington public-schools teachers in a 1999 state survey said salary level would be their main reason for leaving the profession in the next five years.

And in a Seattle Education Association survey last winter, more than two-thirds of respondents supported recruitment and retention bonuses, greater job security and more family-engagement training for those agreeing to work in high-needs schools. In general, respondents also strongly supported more planning time and mentoring for those in their first five years of teaching.

The district employs nine mentors this year, down from 14 in the mid-1990s. Mentors say they serve as a sounding board, a sympathetic ear and a master showing the apprentice what good teaching looks like. They also organize support groups.

Mid-career teachers like Ann Scott, who mentors 16 teachers in 12 schools, get a bird's-eye view of the system while keeping a toe in the classroom.

"A lot of school reform is on the backs of teachers," Scott said. "A lot of us feel like, 'When do I have time to manage all this?' "

Sanjay Bhatt: 206-464-3103