Her schools were heralded as a beacon for educational excellence. And she was seen as a superhero of the sector, transforming the fortunes of America’s poorest and most disadvantaged students. But now she could face up to 35 years in prison over what has been described as the biggest public school cheating scandal in the history of the US.

In 2009, Beverly Hall was named the national school superintendent of the year, thanks to her work improving results in the public schools of Atlanta, Georgia. US education secretary Arne Duncan even played host to Ms Hall at the White House in recognition of her achievements.

A year later, Ms Hall was once again praised for boosting the life chances of Atlanta’s children, and was given a distinguished public service award by the American Educational Research Association. The White House once again rolled out the red carpet and she was entertained by president Barack Obama himself.

Fast-forward four years and Ms Hall, who denies the charges against her, has been accused of overseeing the alteration and then certification of thousands of student exam papers in the state’s standardised tests.

Earlier this month, a grand jury trial started for 12 of the 35 principals, administrators, teachers and back-office staff who were allegedly involved in manipulating scores in order to improve their performance-related pay deals.

Ms Hall’s own trial has been postponed while she is treated for breast cancer. Yet, despite her absence from the current court case, her story and that of Atlanta’s public schools have rocked the US education establishment.

Among the laws Ms Hall has been indicted for violating is the Racketeer Influenced and Corrupt Organizations Act, a piece of legislation usually reserved for prosecuting Mafia bosses.

“This is the largest school cheating scandal in American education law history,” Ronald Carlson, emeritus professor at the University of Georgia School of Law, told TES. “It infected dozens of schools.”

Ms Hall was invited to rub shoulders with fellow exalted guests at the White House because of her apparent achievement of transforming Atlanta into one of the best-performing school districts in the country. Test scores in the schools shot up, in what was deemed a near-miraculous turnaround in standards. But suspicions were aroused and the city’s local newspaper, The Atlanta Journal-Constitution, began to run stories questioning the jump in results.

The state governor got involved, triggering a 21-month criminal investigation. More than 2,000 teachers, students and administrators were questioned and it was found that 44 out of the district’s 56 schools had become embroiled in “systemic misconduct”.

The district attorney alleged that the 35 members of staff who were indicted had “conspired to either cheat, conceal cheating or retaliate against whistle-blowers in an effort to bolster [test] scores for the benefit of financial rewards associated with high test scores”.

Of the 35 originally accused, 21 have since confessed to cheating in exchange for more lenient sentences - most likely to be probation - and one has died.

In all, more than 80 teachers, principals, administrators and educators admitted to so-called “test tampering”. Teachers worked together to correct wrong answers in the multiple-choice exams, while it was claimed that one principal held “erasure parties” where exam sheets were doctored.

“The fact that they are facing, potentially, jail punishment is another factor which makes this case remarkable,” Professor Carlson said. “It is typical, in the American system, that trials of teachers or school staff in criminal court are reserved for two items: theft of school funds or sex with a student. It is rare, perhaps never before heard of, to place teachers in felony court for professional misconduct.”

The ways in which schools and their teachers were incentivised to achieve better results appears to lie at the heart of Atlanta’s cheating scandal. If 70 per cent or more of the district’s schools passed the state’s threshold, then teachers were handed a bonus; if schools fell short of the threshold, they were threatened with potential restructuring, job losses or even closure.

The high-stakes nature of the school improvement measures has led teaching unions, community bodies and parents to hold Atlanta up as a cautionary tale to proponents of linking teachers’ pay to test scores and using exams as the single most important accountability measure.

As the trial of those implicated in the scandal began, Lily Eskelsen Garca, president of the country’s largest teaching union, the National Education Association, wrote a newspaper opinion piece decrying what she called “toxic testing”.

“Too often, and in too many places, we have turned the time-tested practice of teach, learn and test into a system of test, blame and punish,” Ms Eskelsen Garca said. “We are using these tests to punish schools, teachers, students and school districts. This simply isn’t right. It is toxic.”

Tim Callahan, a spokesperson for the Professional Association of Georgia Educators, a statewide organisation of more than 84,000 teachers, administrators and support staff, agreed with Ms Garca’s comments and went even further, claiming that Atlanta’s schools were “ground zero” for the worst of high-stakes testing.

Mr Callahan told TES the example of Atlanta showed that “very bad things may occur” when a system focused on test scores alone, rather than the quality of teaching. He added that a lesson must be learned from the scandal.

“Improving teaching and learning is the sure way, albeit slow, of improving test scores,” Mr Callahan said. “To do as was done in Atlanta sets up a competitive `devil take the hindmost’ situation, in which educators are not colleagues mutually interested in the ultimate success of their pupils but are instead competitors, seeking the quick way to grasp the brass ring for themselves.

“If ever we needed a horrible demonstration that schools are not businesses, and student achievement is not something to be `scored’ like quarterly sales reports, this was ground zero.”

Perverse incentives?

“High-stakes testing” has become an increasingly controversial topic in the US, with students’ results being used to determine a range of outcomes for schools and teachers.

In many states, teachers’ pay is tied to the attainment of their students, while in others, such as New York and California, teachers have been ranked in league tables based on test scores. Poor results can cost a teacher their job.

The drive to use exams as the chief accountability measure was introduced in 2001 under president George W Bush. His No Child Left Behind policy has been built on by Barack Obama, who brought in Race to the Top. Both approaches tied student test scores to teachers’ jobs.

This has led to criticism that education has been continually narrowed, to the point where it has become little more than exam preparation.

Critics have warned that placing so much importance on test scores - for example, by offering bonuses or threatening job losses, as in Atlanta - means that perverse incentives will inevitably follow, encouraging widespread cheating.