WASHINGTON – Like most school systems, the District of Columbia measures student achievement by letter grades and test scores.

For D.C. teachers, school principals determine their fate with classroom observations.

But Washington Schools Chancellor Michelle Rhee and her staff want the current teacher evaluation system to include more indicators of performance, such as peer evaluation or student test scores over time. It’s called a value-added approach, and similar models are in place in other big cities, such as Chicago.

The Washington Teachers Union calls the current system mediocre.

“What we have now is a principal with a checklist,” said WTU President George Parker. “The old method of believing that a single principal can walk in a classroom one day out of the year and effectively evaluate is just not realistic.”

The teachers union may want change, but its officials say they are wary of the district’s plan to include student test scores as an indicator of teacher performance.

“A test scores a student’s performance on a given day,” Parker said. “It doesn’t measure how well a teacher is teaching or the resources (they are) given. (Using test scores) is very tricky.”

The district has invited teachers to a series of focus groups to suggest how tomodify the evaluation process. The meetings have not been well-attended so far, according to teacher union representatives.

According to the teachers union, the district hopes the revamped process will be ready for the upcoming school year.

D.C. school spokeswoman Jennifer Calloway wrote in an e-mail:

"Our goal is to ensure that all educators accurately understand their professional strengths and weaknesses so that they can continually improve their practice.”

The new value-added approach to teacher evaluation will encompass more than feedback from a principal.

Enter Mathematica, the research firm hired by Rhee to process student test scores year-to-year.

“What our firm does is try to estimate the amount of learning gain that can be attributed to certain teachers,” said senior researcher Steve Glazerman. “That way we can try to compare teachers in the district who have similarly-achieving students.”

Some parts of the new evaluation process may include some criteria that cannot be quantified.

“Value-added means different things to different people,” said Jed Wallace, chief executive officer of the California Charter Schools Association. “Maybe it’s student attendance rates, parent or student satisfaction. Or you look at what else the teacher is involved in at the school, like extra-curriculars.”

Wallace and other educators around the country note that Rhee is faced with many challenges.

Just add teacher evaluations to the list.

“There’s clearly a lot of people watching what (Rhee) is doing,” Wallace said. “She’s tackling a lot of issues that weren’t tackled in the past. Teacher evaluations? Certainly a lot of teachers in the district aren’t used to that being a big issue.”

The new models are not perfect, but administrators say they cannot afford to wait.

“Let’s move forward with these adult accountability systems,” Wallace said. “We have to go with something. We owe it to the children that are in school right now.”