It's no secret that one of the keys to creating better schools is to raise the quality of teaching in the nation's classrooms. But how to identify, and encourage, high-quality teaching is proving to be a challenge.

Several efforts to address this question are under way. The Bill & Melinda Gates Foundation has just launched a five-year, $500 million initiative to quantify what, exactly, makes a teacher effective and how to tie that to student achievement (see story). And the Obama administration has cited improving teacher quality as one of four education-reform areas it plans to target in particular. (See "Duncan outlines school reform agenda.")

Education Secretary Arne Duncan has said he supports merit pay for teachers--a practice linking raises or bonuses to student achievement. He also said test scores alone should not decide a teacher's salary, "...but to somehow suggest we should not link student achievement to teacher effectiveness is like suggesting we judge sports teams without looking at the box score."

Duncan also is using federal stimulus dollars to press the issue.

Later this year, states will compete for a piece of $5 billion in "Race to the Top" stimulus funding, which rewards those states and school systems that adopt innovations the Obama administration supports. Whether officials tie student data to teacher evaluations will be a consideration in awarding the grants, said Duncan.

Although relatively rare, the use of pay-for-performance programs appears to be growing, albeit slowly. According to analyses of data from the "Schools and Staffing Survey" administered by the U.S. Department of Education, 13.6 percent of districts rewarded excellence in teaching in 1999-2000, and 14 percent rewarded excellence in teaching in 2003-04.

In 2003-04, 19.6 percent of districts said they rewarded some schools for excellence in teaching through a school-wide bonus or additional resources for a school-wide activity, and 15.4 percent of districts said they provide a cash bonus or additional resources to individual teachers to encourage effective teaching.

The key challenge in implementing pay-for-performance systems, experts agree, is how to define teacher excellence. The most obvious way would be to look at student achievement, as Duncan wants to do. But that's controversial, as many people believe test scores alone paint an unfair or incomplete picture of a teacher's contribution.

A recent survey, "Exploring the Possibility and Potential for Pay for Performance in America's Public Schools," conducted by the American Association of School Administrators (AASA), revealed the motivations and concerns that influence superintendents' consideration of pay-for-performance systems.