Education officials are blaming a drop in Missouri students’ academic performance last year on the state changing its standardized testing and the threshold for passing four times in five years.

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

Brent Ghan of the Missouri School Boards’ Association says board members and administrators are frustrated by the changing assessments. Ghan says the assessments are more difficult because they’re based on higher expectations and different standards.

St. Louis Public Schools Superintendent Kelvin Adams says the state also changed the way questions are asked, which required students to think differently.