An outside audit offers only "educated speculation" for drastically lower writing scores on this year's Florida Comprehensive Assessment Test.
State officials on Tuesday also released the final batch of FCAT 2.0 scores in other subjects, saying they were better than expected.
Overall, 57 percent of students scored on or above grade level in reading in grades three through 10. The figure also was 57 percent for math in grades three through eight.
In each case that was a 1 percentage point improvement compared to revised 2011 grades based on this year's tougher scoring standards.
The writing test audit said more rigorous scoring and increased standards may have caused the low scores.
In response, the State Board of Education lowered the passing score for the writing exam.