Award-winning gains by Atlanta students were based on widespread cheating by 178 named teachers and principals, said Georgia Gov. Nathan Deal on Tuesday. His office released a report from the Georgia Bureau of Investigation that names 178 teachers and principals – 82 of whom confessed – in what's likely the biggest cheating scandal in US history.

This appears to be the largest of dozens of major cheating scandals, unearthed across the country. The allegations point an ongoing problem for US education, which has developed an ever-increasing dependence on standardized tests.

The report on the Atlanta Public Schools, released Tuesday, indicates a "widespread" conspiracy by teachers, principals and administrators to fix answers on the Criterion-Referenced Competency Test (CRCT), punish whistle-blowers, and hide improprieties.

It "confirms our worst fears," says Mayor Kasim Reed. "There is no doubt that systemic cheating occurred on a widespread basis in the school system." The news is “absolutely devastating," said Brenda Muhammad, chairwoman of the Atlanta school board. "It’s our children. You just don’t cheat children.”

On its face, the investigation tarnishes the 12-year tenure of Superintendent Beverly Hall, who was named US Superintendent of the Year in 2009 largely because of the school system's reported gains – especially in inner-city schools. She has not been directly implicated, but investigators said she likely knew, or should have known, what was going on. In her farewell address to teachers in June, Hall for the first time acknowledged wrongdoing in the district, but blamed other administrators.

The Atlanta cheating scandal also offers the first most comprehensive view yet into a growing number of teacher-cheating allegations across the US, reports of which reached a rate of two to three a week in June, says Robert Schaeffer, a spokesman for the National Center for Fair & Open Testing, which advocates against high-stakes testing.

It's also a tacit indictment, critics say, of politicians putting all bets for improving education onto high-stakes tests that punish and reward students, teachers, and principals for test scores.

"When test scores are all that matter, some educators feel pressured to get the scores they need by hook or by crook," says Mr. Schaeffer. "The higher the stakes, the greater the incentive to manipulate, to cheat."

Cheating in Atlanta Public Schools
The 55,000-student Atlanta public school system rose in national prominence during the 2000s, as test scores steadily rose and the district received notice and funding from the Broad Foundation and the Gates Foundation. But behind that rise, the state found, were teachers and principals in 44 schools erasing and changing test answers.

One of the most troubling aspects of the Atlanta cheating scandal, says the report, is that the district repeatedly refused to properly investigate or take responsibility for the cheating. Moreover, the central office told some principals not to cooperate with investigators. In one case, an administrator instructed employees to tell investigators to "go to hell." When teachers tried to alert authorities, they were labeled "disgruntled." One principal opened an ethics investigation against a whistle-blower.

Investigations by the Atlanta Journal-Constitution (AJC) and state investigators found a pattern consistent with other cheating scandals: a spike in test scores in one critical grade would be followed by an equally dramatic drop the next year. A USA Today investigation in March found that erasure data in six states and the District of Columbia showed these "abnormal patterns," according to testing expert Thomas Haladyna at Arizona State University.

The Atlanta testing allegations led to the first major law enforcement investigation of teacher cheating. Scandals in other states have typically been investigated by state officials. In response to recent teacher cheating allegations in Baltimore, Michael Sarbanes, the district's community engagement director, told District Management Journal, an industry publication for school administrators, that manipulating a test is "inherent in human nature, [although] we think people who do that are outliers."

Ten states now use test scores as the main criterion in teacher evaluations. Other states reward high-scoring teachers with up to $25,000 bonuses – while low scores could result in principals losing their jobs or entire schools closing. Even as the number of scandals grows, experts say it remains fairly easy for teachers and principals to get away with ethical lapses.

"I think the broadest issue in the [Atlanta scandal] raises is why many school districts and states continue to have high-stakes testing without rigorous auditing or security procedures," says Brian Jacob, director of the Center on Local, State and Urban Policy at the University of Michigan. "In some sense, this is one of the least worrisome problems in public education, because it's fairly easy to fix. The more difficult and troubling behavior would be teaching to the test, which we think of as a lesser form of test manipulation, but which is much harder to detect, and could warp the education process in ways that we wouldn't like."