An error by the vendor for Ohio’s standardized tests meant that thousands of high school students incorrectly scored zeroes on their English essays.

All of the approximately 5,300 exams for English Language Arts I and II have been rescored by the American Institutes for Research, according to Brittany Halpin, a spokeswoman for the Ohio Department of Education. The error affected less than 6 percent of the 90,000 English exams taken by Ohio high school students last fall.

Several central Ohio school districts had tests rescored. Among them were 38 at Pickerington, one at Johnstown-Monroe, three at Northridge, 127 at South-Western, 25 at Groveport Madison, 23 at Westerville and nine at Olentangy schools. A Dublin schools spokesman said some scores there were affected, but he was unsure how many.

Computers at AIR "read" and score the essay portion of the English language arts tests, which are given to third-graders and older students. Ohio switched to automated grading of its English tests this school year.

As Jon Cohen, AIR’s president of assessment, explained in February, when too much of a student’s essay is copied directly from the provided reading passage on the exam, the computer flags it and flunks it because there isn’t enough original work to grade. AIR programs into its computer the required percentage that must be a student’s own words for the essay to earn points.

For Ohio, that’s at least 30 percent original, Halpin said. But the AIR staff accidentally typed in 50 percent. She emphasized in an email that this was a human error, not a computer error.

"We are very disappointed that AIR did not have appropriate quality-control checks in place to catch this issue early in the scoring process," Halpin said in an email. "We are working closely with them to ensure that proper checks are in place going forward."