Tallahassee, Fla. (AP) --

The head of Florida's Department of Education is writing parents to tell them that they shouldn't be overly concerned about the results of the state-required exam that's supposed to measure year-to-year improvements of students, teachers and public schools.

Education Commissioner Gerard Robinson said changes to the testing program resulted in some lower scores, but said the results shouldn't be interpreted as lower performances by students, teachers and schools. About half of the state's ninth and 10th grade students failed the reading portion of the new, more rigorous Florida Comprehensive Assessment Test.

Robinson explained that new assessment procedures were used to measure progress resulting in the lower scores this year. The scores have prompted some school administrators around the state to call for scrapping the controversial testing program.