About 75 percent of New Jersey teachers are rated as "effective" under a new system that attempts to be more specific about their strengths and weaknesses.
But 13 percent of students were instructed by the relatively small group of teachers who were deemed "ineffective" or "partially effective."
The state released results from the 2013-14 statewide rollout of the new evaluation system on Monday.
The system has been the subject of intense debate in part because it uses students' performance on standardized tests as one measure of how well some teachers are doing. Specifically, the evaluations consider how much students improve compared with similar students. Those data are used only for teachers of subjects and grades for which the tests are required.
Previously, teachers were classified as "acceptable" or "unacceptable." More than 99 percent were found to be "acceptable."
Under the new system, there are four divisions. Only 0.2 percent ranked as "ineffective," but 2.5 percent were found to be "partially effective." Teachers with either of those ratings must go through corrective action plans and can risk losing tenure if they do not improve in time.
Just over 23 percent were in the highest category, "highly effective."
The state Department of Education's chief talent officer, Peter Shulman, said school districts that had pilots of the new evaluations for one or two years before the statewide implementation are doing more than just figuring out which teachers need improvement.
"We believe the actual improvement is happening in the classrooms," he said in a telephone interview on Monday.
The four classifications in the new system came from a 2012 law that made tenure protections more difficult for teachers to earn and easier for them to lose.
State Sen. Teresa Ruiz, an architect of that law, said, "We must move forward with our work under this new system to make good teachers great and great teachers exceptional."
Wendell Steinhauer, president of the New Jersey Education Association, the state's largest teachers union, said he is glad that most teachers are receiving high ratings but wants more information, including whether the system is biased against those who teach special education, students who are learning English or students in impoverished communities.
He also said that if the evaluations do provide worthwhile information, teachers' scores will improve.
Follow Mulvihill at http://www.twitter.com/geoffmulvihill