What’s the best way to evaluate a teacher’s performance? Some say it’s students’ test scores; others say it’s the job of a professional administrator.

While the most accurate evaluation probably uses elements of both, there is another source of information that is often neglected in the school reform debate and that’s the students themselves.

A $45 million research project funded by the Bill and Melinda Gates foundation suggests it’s time to change our way of thinking.

The researchers, working with 3,000 teachers and their students in six cities, found a strong correlation between “value added” testing, which measures how much teachers helped their students based on improvement in test scores, and anonymous evaluation forms filled out by students.

Classrooms where a majority of students said they agreed with the statement “Our class is busy and doesn’t waste time” were more likely to be led by teachers with high value-added scores.

And classes that said “We learn to correct our mistakes,” or “My teacher has several good ways to explain each topic,” were also places where the students made the most progress.

It’s obvious — kids who spend their whole day in a classroom and experience a variety of teaching styles are in a better position to determine which teacher is the most effective than almost anyone else, including administrators, the teacher’s colleagues or the students’ parents.

The students may not have the vocabulary to critique a teacher the way a principal would, but they know good teaching when they see it, and they have a lot more information to work with than the administrator. Their observations should be taken seriously.

In an unsuccessful attempt to apply for federal funding through the Race to the Top program, Maine passed a law allowing some portion of teacher evaluations to be based on student performance.

The Gates Foundation study shows that students’ scores don’t tell the whole story about what is going on in the classroom, however.

For instance, teachers whose students agreed with the statement “We spend a lot of time in this class practicing for the state test,” made smaller gains on the value added scores than the teachers who did not teach to the test.

Providing teachers with meaningful feedback and giving them support they need to improve is what the evaluation process is all about. That means talking to the experts — the students in their classes — and using those insights to teach the teachers how to do a better job.