Last March, I quoted at length an anonymous D.C. principal who thought that the city’s new teacher evaluation system was making her less effective. At my request, D.C. officials put me in touch with another principal, Carolyne Albert-Garvey of Maury Elementary School in Northeast Washington, who says the new system works well for her.

It is important to discern why two hard-working administrators have such different views. The IMPACT system of requiring five observations of each teacher each year by school administrators and outside experts, plus test score data for teachers in some grades, is being closely watched nationally. Its success or failure will have a large effect.

The two principals’ schools are different. About 78 percent of Maury students are from low-income families. Thirty-eight percent tested proficient or advanced in reading and 35 percent in math in 2010.

I promised the anonymous principal not to identify her or her school because she feared central office reprisals for being critical of IMPACT. Her students are significantly less poor and more proficient in reading and math than Maury’s students.

The anonymous principal complained that before IMPACT forced her to do three half-hour observations and reviews of her findings with every teacher, she had time to visit each classroom more often, getting a good sense of both teachers and students.

With IMPACT, she said, “I rarely am seen walking around the school since I have specific appointments to keep in the classrooms. ... I can rarely compare what is happening from room to room since the visits are on different days at different times. The teachers have started commenting on the fact that the students rarely see me anymore. ... I feel my knowledge of specific students and their needs is slipping away.”

Albert-Garvey says she stays in touch this way: “I may conduct two formal 30-minute observations, conduct three 15-minute informal observations and visit three classrooms with a focus on students and student work on one day. On another day, I may conduct informal observations only. On the third day, I may have two teacher conferences scheduled during their planning period and visit two classrooms.”

She visits every classroom and can be seen by every student every day, although the contact can be fleeting. “I visit all classrooms every morning between 8:50 and 9 a.m. This visit is informal and allows me to say good morning to all staff and students. I stay in each room about 15 seconds,” she said.

She visits the cafeteria each breakfast and lunch to check on students “even though it may be only for 10 minutes,” she said. When classes are in session, she said, “I never spend more than 20-minute chunks of time in my office. I never carry a phone or Blackberry with me in the building to avoid being distracted by calls or e-mails. I carry a walkie-talkie in case the office needs me and it better be for a good reason.”

She is in the main hallway from 3 to 3:30 p.m. to greet parents and monitor student dismissal. She doesn’t do office paperwork until after dismissal. She devotes four to six hours each Sunday at school getting ready for the week.

The anonymous principal said she had a much better grasp of how each teacher was doing before IMPACT, when she could make shorter, more frequent visits. IMPACT may make more demands on her than on Albert-Garvey because the anonymous principal has significantly more students and teachers.

Albert-Garvey did not say so, but I sense that she thinks IMPACT better informs teachers what they need to do to succeed. “It provides clear expectations and a clear process for me and for my staff,” she said. “Also, deadlines are good for all involved.”

Can good principals have different ways of getting good results? Sure. Can they and IMPACT adjust to get the best results for every child? Wait and see.