RALEIGH — North Carolina needs a better system to rate school performance, lawmakers said Tuesday.

Traditional public and charter schools are scored on a scale from A through F. The system looks at student achievement for 80 percent of a school’s grade. Student growth scores, which measure a child’s academic improvement year over year, account for the remaining 20 percent.

House Bill 322 would assign different weights to aspects comprising the final grades.

A 50 percent weight on both achievement and academic growth would make for more accurate reports on how a school is doing, said Rep. Craig Horn, R-Union, a primary sponsor.  

Student growth should count for more in measuring a school’s performance, he said.

Recalculating grades may be a good idea, but some disadvantages exist and should be considered, said Terry Stoops, director of research and education studies at the John Locke Foundation.

“There is no one best system of calculating school performance grades. There are advantages and disadvantages to changing the formula to give equal weight to school achievement scores and student growth scores, as House Bill 322 would do if passed in its current form,” he said.

State educators would support the change, he said, because student performance measures are somewhat arbitrary.

But while a shift in the grade scale might make sense to lawmakers, a mashup of inevitable school grade changes would probably confuse parents familiar with the current system.

“A system that made the measure of school performance intelligible to the public would … confuse the public by showing a radical grade improvement or decline from one year to the next,” Stoops said.

The House is expected to vote on H.B. 322 this week.