Maryland has approved new teacher evaluation systems in Prince George's County Public Schools and 20 other Maryland school systems, clearing the way for the state to receive $250 million in federal funds, the Maryland State Department of Education announced Thursday.

Schools in Montgomery and Frederick counties opted out of the federal Race to the Top grant to avoid meeting federal and state requirements, and approval of Baltimore City Public Schools' plan is still pending.

Prince George's was among seven local school systems whose initial evaluation systems were rejected in January. The county's original plan did not use performance on statewide standardized tests to account for at least 20 percent of the evaluations, a threshold that state officials established in agreement with the U.S. Department of Education.

The plan approved Thursday bases 15 percent of each evaluation on the statewide Maryland School Assessment, or MSA, standardized test, said Maryland State Education Association Vice President Cheryl Bost. For a fifth-grade teacher, for example, the school system measures the change between students' scores when they are in fourth grade and when they are in sixth grade.

The last 5 percent is based on the "school progress index," a measure that uses the MSA to evaluate schools in three categories: achievement, student growth, and the gap between the lowest- and highest-performing students.

A Prince George's school system representative did not return requests for comment.

Many teachers and school districts across the state initially protested the standardized test requirement.

"The data comes back once the students have already left your staff, the data that you do receive does not help you make any changes that you need to help your students, and MSA was never designed to measure growth," Bost said.

The standard originated with a federal requirement that student achievement be a "significant factor" in the evaluations, explained Anne Hyslop, a policy analyst at the New America Foundation's Education Policy Program. It was a requirement that many states struggled with, she said.

Nationally, many teachers viewed the requirement as punishment. This, Maryland State Superintendent of Schools Lillian Lowery said, is far from accurate.

"The evaluation plans are designed to improve professional development for educators, first and foremost -- not as a punishment system," she said.

Research has backed the reliance on student achievement, Hyslop said.

"We know that quality teaching matters, and it's one way that we're trying to build a system of highly effective teachers."