Three Washington, D.C., schools cheated on 2011 standardized tests, according to a forensic report the district will release today.

Of the 38 Washington, D.C., schools flagged for further investigation for cheating, 23 were found to have some degree of test violations. D.C. flagged classrooms for further investigation only if they met two of three criteria: the number of answers erased from wrong to right as compared to the state average; unusual gains in test scores; and scores within a classroom that don't fit on a bell curve. It also flagged schools that had more than one consecutive year of high erasure rates. In 2011, 70 of 5,089 tested classrooms were flagged for further investigation, including 36 public schools and 34 charter schools out of 262 tested schools in D.C.

In other cheating cases cases, statisticians say, classrooms that have had a wrong-to-right erasure ratio more than two standard deviations from the average are so irregular that they warrant a further look on their own -- regardless of whether abnormal right-to-wrong erasures occurred two years in a row.

The test in question is the District of Columbia Comprehensive Assessment System (DC CAS), which D.C. administered in 262 schools in 2011. The flagged classrooms are in 38 of these schools. These scores are used for high-stakes decisions, including teacher evaluations and hiring. Three of the 23 schools with testing issues, Martin Luther King, Langdon and Perry Street Prep, received a "critical" designation, and the results on those tests will be invalidated. Ten schools received a "moderate" designation, and will also have their results invalidated. Ten schools received a "minor" designation and will receive a letter of reprimand. The Office of the State Superintendent of Education hired an outside firm, Alvarez & Marsal, to look at the tests for the first time.

“Today’s investigation results show that in 99.94% of classrooms, our teachers, administrators and school communities are playing by the rules,” State Superintendent Hosanna Mahaley said in a statement.

The validity of standardized tests receive tremendous amounts of scrutiny because, over the last decade, test scores have become the linchpin of education policy. For the first time, many states are using them to evaluate teachers. While teacher cheating has likely always occurred to some extent since the dawn of standardized tests, the issue captured public attention last summer, when Georgia's equivalent of the FBI found evidence of 148 educators altering test scores to make their schools look better. It became known as the largest cheating scandal in American history. And last year, a USA Today investigation that found that several classrooms in Washington, D.C., had a high rate of answers erased from wrong to right, often a sign of teacher test-tampering. The report spurred further investigations, including one conducted by the U.S. Education Department's Inspector General's office that is still underway.

Kaya Henderson, D.C.'s schools chancellor, has previously said that a lack of national standards makes it hard for school districts to assess the extent of cheating in a consistent way. That's why the U.S. Education Department convened a number of cheating experts this spring to work on guidelines school districts can use to prevent and root out cheating. Friday's report is part of the safeguards D.C. has since placed on testing -- a routine look at whether the state's standardized test scores from 2011 can be trusted. For example, the report details how CTB/McGraw Hill stepped up its training for all employees dealing with tests; how the district gave 80 schools special monitoring; how test booklets were secured before the exam; and a more open form to report possible hiccups in the testing process.

The 2011 investigation included 300 interviews that took place in 15 percent of the district's schools, and found testing issues in 9 percent of schools and one percent of classrooms. The report concludes that "tighter protocols are needed across the board." D.C. also found cheating in three classrooms in 2010.

See below for the full text of A&M's report, its report to the state and D.C.'s presentation on its findings.

Project Columbia Report 062212 Final

A&M 2011 DC CAS School Summary Reports

UPDATE 12:35 p.m.: This story was updated to include A&M's full reports on its investigation.