Some US school administrators - under mounting pressure to show positive results from educational reform - have been tampering with students' test results.
A New York State superintendent was forced to resign after allegations that teachers were ordered to correct third graders' wrong answers on performance tests.
The administrators of a Connecticut school are accused of erasing their students' mistakes. In Chicago, a teacher was fired after letting students practise questions that appeared on a skills test later given to them.
The incidents come as educators are being pressed for tangible evidence that school reform is working. Some districts have tied teacher salaries and principals' bonuses to student test scores.
"When you tell administrators that their test scores have to go up or else, or you say to teachers that their salary is going to be dependent on their children's test scores, the temptation to tamper with those tests is obvious, " said Carole Kennedy, an elementary school principal in Columbia, Missouri.
"I'm certainly not condoning that. Integrity is more important than test scores."
Where answers appeared to have been erased and rewritten teachers were escorted from the Stratfield School in Fairfield, Connecticut, to the test publishing company in Iowa by a police officer. The principal of the award-winning school voluntarily submitted to a lie-detector test.
School board officials noticed that original answers had been rubbed out when they were comparing the scores of third and fifth-graders with those of students at other schools.
Answers on a second test also were discovered to have been erased.
A teacher was fired in Chicago and a principal suspended without pay for keeping old copies of skills tests and giving them to students.
The students then sat the same tests. The incident occurred after the district began requiring students to score above a certain level in order to be promoted to the next grade.
Officials are investigating allegations that the same thing occurred in two other Chicago elementary schools.
And an elementary school principal in Hawaii had teachers fill in the answers on a third- grader's incomplete achievement test.
"There's a lot of anxiety on the part of administrators right now," said Ms Kennedy, president of the National Association of Elementary School Principals.
"If we could figure out how to measure how much the children have improved, rather than how they score, we'd be a lot better off."