(AP) — A leading expert says using student test scores to evaluate teachers based on the test scores of their students is risky and potentially misjudges the work of otherwise good teachers.

University of California, Los Angeles, professor emeritus James Popham addressed a conference on testing and instructional quality this week at the University of Kansas.

Popham and other speakers expressed concern that many high-stakes, standardized exams may test what students know without testing whether they have a good teacher or not.

Kansas and many other states are moving toward new systems of teacher evaluation in which teachers are assessed based in part on student scores on annual mathematics and reading tests.