This piece comes to us courtesy of Education Week, where it was originally published.

This year, Principal Jennifer Hammond and her team of assistant principals will conduct three formal classroom observations of every teacher at Grand Blanc High School, a campus of 2,700 students in suburban Flint, Mich.

With 135 teachers, that breaks down to roughly 100 classroom visits for each of the four administrators to evaluate faculty members who teach a wide array of courses, from Chinese language to woodworking.

"We'll spend somewhere between 25 and 55 minutes in each class, for each visit," said Ms. Hammond. "The research tells us that we need to have somewhere between four and six observations that each last at least 15 to 20 minutes to have good data."

Though teachers at Grand Blanc receive written feedback on their lessons and instruction following each classroom visit, it won't be until May, after the third and final observation, that many will sit down face-to-face to talk with Ms. Hammond or one of her assistants about what they did well and how they can get better.

"In a perfect world, we'd have a post-observation meeting with every single teacher, but it's not possible with the time we have," said Ms. Hammond.

Such a reality--that principals' time is too often strained by other requirements of the job to make room for substantive instructional coaching--is running headlong into the increasing demand for school leaders to be inside classrooms, watching and studying teachers, and helping them improve as part of new teacher-evaluation systems. And on top of that, there is scant evidence to show that the more time principals spend inside classrooms, the better student achievement will be.

In a study published late last year in the journal Educational Researcher which examined instructional leadership practices in the 350,000-student Miami-Dade County, Fla., school system, researchers found that the amount of time that principals spent on a broad range of activities related to instruction was not associated with gains in student performance, as measured by standardized tests.

Role of 'Walk-throughs'

After delving more deeply into specific practices and behaviors of instructional leadership, however, researchers Susanna Loeb and Ben Master of Stanford University and Jason Grissom of Vanderbilt University, found that classroom "walk-throughs"--the most typical instruction-related activity of principals in Miami-Dade schools--were negatively associated with student performance, especially in high schools.

But the time that principals spent on coaching teachers or working to improve the school's curriculum did predict positive achievement gains, especially in mathematics.

The study closely documented how the Miami-Dade principals spent their time by having trained observers follow more than 100 of them around for one full school day in each of three school years and record their activities. That information was paired with data on each administrator provided by the school district, along with survey data and interview responses provided by the principals themselves.

Overall, the results showed that principals spent an average of 12.7 percent of their time on activities related to instruction, and the biggest chunk of that time-- 5.4 percent--was devoted to conducting brief classroom walk-throughs. Elementary school principals spent more of their time on instructional activities than their high school counterparts, the study found.

"It's not that those classroom walk-throughs can't be positive, it's just that they are particularly negative if principals don't follow up with some kind of meaningful professional development for teachers," Ms. Loeb said.

In follow-up interviews with some of the principals, the most common reasons they cited for conducting classroom walk-throughs were to check up on teacher practices in order to gather information and to be visible to staff members. A smaller number of principals cited opportunities to provide coaching as their primary reasons for doing the walk-throughs.

The study also revealed that even when principals themselves viewed classroom walk-throughs as a valuable tool for professional development, they reported that many of their teachers did not share that view.

"Many principals see these walk-throughs as very positive," said Ms. Loeb. "This is how they check to make sure that teachers are teaching the material and how they let teachers and students know they are present and are paying attention to what is happening inside classrooms."

So, what's a principal--whose duties as an instructional leader continue to ratchet up with the colliding rollouts of new academic standards, new assessments, and new teacher-evaluation systems--to do?

Two professional organizations for school leaders--the National Association of Elementary School Principals, or NAESP, and the National Association of Secondary School Principals, or NASSP--have been toiling to come up with some answers.

Training for Trainers

Last month, the two groups released recommendations that outline actions that they say federal, state, and local policymakers can take to support principals as they take on more responsibility for evaluating teachers.

Chief among the NAESP and NASSP recommendations directed at federal education authorities: Requiring states and districts to spend at least 10 percent of their federal Title II funds from the Elementary and Secondary Education Act on professional development for principals. Currently, the associations said, nearly all of that money is directed at a range of teacher-quality efforts that districts choose to focus on, with less than 4 percent spent on principal-related professional development.

There's also a major chasm in some states and districts between what principals are expected to do with new evaluation systems and their preparedness to actually carry out those expectations, said Maribel Childress, the principal of Monitor Elementary School in Springdale, Ark., and a member of the committee that made the recommendations.

"We found in our discussions with colleagues that there is little to no professional development for principals on how to conduct teacher evaluations, how to use the rubrics themselves when you go into a classroom, or how to provide professional development to teachers so that they understand the process," Ms. Childress said. "These things should be, and are, much more complicated than checking off a list."

In her own school of 800 students and 80 staff members, Ms. Childress and one assistant principal are required this year to conduct about 30 hours of joint professional development with teachers, so that everyone understands the precise standards they will eventually be judged on. Just recently, Ms. Childress, the assistant principals, and peer teachers divided up classrooms and spent time in each one to record how well teachers are communicating with students and how effective they are at questioning students and prompting discussions.

"We tackle one or two pieces of the rubric every week," said Ms. Childress. "We share our observations on those with teachers right away. We are trying to make the coaching aspects of this a constant process."

'Fantastic Tools'

Arkansas also requires principals and assistant principals to complete training on the new teacher-evaluation rubric and then tests them on it before they can become certified to evaluate teachers.

"I think these evaluation systems could be fantastic tools for moving teachers forward and helping them improve their craft," said Ms. Childress, "but if we don't have a good understanding of the tools, it will fail."

And, again, there is the time issue.

The principal associations, in a 2013 survey of their members, found that a "substantive" teacher evaluation requires 11-15 hours per teacher over the course of a school year. They also found that, on average, principals are managing 10-40 staff members in smaller schools and upwards of 60 personnel in bigger schools.

Ms. Childress is fortunate to have an assistant principal who can share some of the demands of evaluation and other pieces of instructional leadership. Many elementary school principals do not.

Ms. Hammond, the Michigan high school principal, also served on the committee of school leaders that made recommendations. She said carving out both the time--and the training--for instructional coaching needs to be a much higher priority in many districts.

"Just watching for the sake of watching isn't going to get our teachers and our schools where we want them to be," she said. "But school leaders also have to know how to coach and have those conversations with teachers about their practices.

"It's not easy going into a classroom of a 20-year biology teacher to sit down to have a conversation about what they need to get better at," she said. "As leaders, we have to make sure our messages are clear and that there is a genuine dialogue with our teachers. We can't just be telling them how to do their jobs."

Coverage of leadership, expanded learning time, and arts learning is supported in part by a grant from The Wallace Foundation, at www.wallacefoundation.org. Education Week retains sole editorial control over the content of this coverage.