Just after 9 a.m. on a recent Thursday, she slipped into the back row of an eighth-grade English class to observe Daniel Leake, a second-year teacher who bounded around the room, quizzing his 19 students about Edgar Allan Poe's "The Raven."
"You have the content of a strong lesson," Miller wrote in her notes. "However, it would be more effective to have a [handout] to help students organize their thoughts/ideas."
After 11 minutes, Miller left. She saw room for improvement: Leake hadn't called on enough students, and he'd answered most of his questions himself. The room was clean, but its sky blue walls were nearly bare.
Still, Leake was doing better than in his first year, Miller said, when he struggled to control his class. She said she would drop in several more times before doing a formal evaluation but thought Leake would merit tenure.
Evaluation is an especially heavy burden at Gompers, where Miller says 31 of 73 teachers are "probes," as probationary teachers are known. Choosing the right teachers will be essential to stabilizing a campus plagued by low test scores and staff turmoil, including seven principals in the six years before she arrived in 2008, Miller said.
Probationary teachers are not distributed evenly throughout the district: Most schools with the highest number of probationary teachers are in poor areas, an analysis of district data found.
"You're putting new teachers who are struggling in with the kids with the highest needs," Miller said.
Last year, Miller said, she told three of 13 teachers up for tenure that they wouldn't get it. Other schools with lots of probationary teachers are less selective.
Consider five academically struggling elementary campuses in South Los Angeles: 118th Street, 116th Street, 75th Street, 66th Street and 24th Street schools.
In the last three years, 88 teachers at those schools have been up for tenure, district data show; only one, at 24th Street last year, was let go by the school board.
District officials noted that other teachers may have known they were going to get a bad evaluation and quit before being fired. At least 15% of teachers leave voluntarily after their first year.
Teacher evaluations at L.A. Unified are known among staffers as "drive-bys."
Not just quick and infrequent, they are also vague and subjective. Both tenured and non-tenured teachers are rated on a four-page checklist with such criteria as "provides an effective classroom environment." The form has three options: meets standards, needs improvement or falls below standards.
There is limited room for an evaluator's comments, but they are often absent or sparing, teachers say. The findings are required to be discussed with teachers in a conference but often aren't.
District data show that probationary teachers pass evaluations at about the same rate as tenured instructors, despite new instructors' inexperience. They are made permanent automatically unless tenure is vetoed by the principal and ultimately the school board -- something that happened an average of 35 times annually in the last four years.
Gonzalez, the Virgil Middle School teacher who this year won a prestigious Milken award for teaching science, said his new principal carries out rigorous evaluations. But when he earned tenure in 2005, he got nearly no feedback.
"It's the culture," he said. "It did make me angry. It still does."
Maine of North Hollywood, who now leads the school's science Olympiad team, could recall only one observation by an administrator in his first few years, "and that was a couple of minutes."
"Being quickly satisfied that no riot was in progress, he departed," Maine said in an e-mail.
Two teachers elsewhere told The Times that their evaluation forms were falsified to show an observer was present when he or she was not. Both declined to be identified for fear of retribution.
The dearth of feedback has only worsened in recent years, as budget cuts have thinned the ranks of assistant principals, who are often responsible for evaluations.
Michelle Ereckson, a third-grade teacher at 24th Street and the school's union representative, said some administrators don't even show up for scheduled evaluations.
When evaluators do show up, Ereckson said, some teachers are well-prepared because they practiced the lesson with students the day before. Evaluators don't seem to notice, she said, even when students know all the answers.
Ereckson said she had reported her concerns up the ladder, all the way to the local superintendent. "No one does anything about it," she said. "Nobody cares."
She thinks it's no accident that the school's state test scores fell last year. "If the principal doesn't know what's going on in the classroom, you can't offer support to the people who need support, you can't offer praise to the people who need praise," she said.