ST. LOUIS (AP) — Education officials are blaming a drop in the academic performance of Missouri students last year on the state changing its standardized testing and the threshold for passing four times in five years.

The percentage of students passing English exams statewide dipped to 49 percent last year, down from 61 percent in 2017, according to state data. Math scores fell to 42 percent in 2018, down from 47 percent in 2017, the St. Louis Post-Dispatch reported.

“What we’re hearing from school board members and administrators is to a large extent frustration that we’ve had these changing assessments,” said Brent Ghan of the Missouri School Boards’ Association. “Scores could be interpreted as being lower, but what’s really happening is we’ve got assessments based on higher expectations and different state standards.”

Missouri adopted national Common Core standards a few years ago, but lawmakers ditched the standards in 2016 following conservative backlash. The Legislature ordered new education benchmarks, and state officials scrambled to develop their own metrics and tests. Last year marked the first time the tests were given across the state.

Superintendents said the state changed how questions are asked on the tests and required higher scores to pass.

Pattonville Superintendent Tim Pecoraro said 85 percent or more of his high school students typically pass the Algebra II test, but roughly 56 percent passed last year.

“It’s not because this group can’t do Algebra II,” Pecoraro said. “The threshold changed. That’s why our message to staff is we’re not going to freak out.”

State law prohibits the education department from stripping a district of its accreditation based on the first year of a new test. The rule has led the department to adjust test scores.

Unlike many districts, the Kansas City School District recorded its highest test score in decades last year. The district lost its accreditation in 2011 and returned to a provisional range in 2014.

Kansas City will need to score at least 70 percent on the test next year to regain full accreditation.

Missouri administrators have promised districts that the state test won’t change again.

Kevin Freeman, an education department official, said, “There is a sense of relief that we’re going to have stability moving forward.”