Those who defend the D.C. schools against charges of test tampering ignore the fact that Georgia authorities uncovered massive cheating in Atlanta, where the levels of wrong-to-right answer sheet erasures in 2009 were very similar to those in the District.

The Georgia investigators identified 178 adult culprits by conducting 2,100 interviews at 56 schools and reviewing 800,000 documents. D.C., by contrast, quickly accepted the suggestions from teachers that the children were responsible for unerringly erasing wrong answers and finding right ones, a view derided by experts.

To get a sense of why investigations in these two cities differed so dramatically, consider what happened at two elementary schools with nearly identical indications of test tampering, Venetian Hills in Atlanta and J.O. Wilson in the District.

At the Atlanta school, the CTB/McGraw-Hill testing company found that 75 percent of the school’s classrooms had wrong-to-right erasures at levels that experts say indicate tampering by adults. At the D.C. school, the same company found 83 percent of classrooms had wrong-to-right erasures at that same high level.

Within a year, then-Gov. Sonny Perdue ordered a Georgia Bureau of Investigation probe of Venetian Hills and 55 other Atlanta schools for test tampering by school officials, a state crime. In the District, however, school officials never sought a criminal investigation of the questionable scores.

Instead, in 2009, they asked the Caveon consulting company to look at just eight schools, where no one confessed to cheating. J.O. Wilson was not investigated at all that year even though its percentage of classrooms flagged for high wrong-to-right erasures in 2009 topped every school but one in the city.

A second Caveon investigation of 10 schools after the 2010 tests found one teacher at Noyes Education Campus who helped students pick the right answers. D.C. officials did not ask Caveon to investigate J.O. Wilson that year either, even though 100 percent of its classrooms were flagged for high wrong-to-right erasures.

Instead,the D.C. schools rewarded J.O. Wilson for its high scores on the 2009 tests — 77 percent proficiency in math and 72 percent proficiency in reading. Principal Cheryl Warley got $10,000, and each teacher got $8,000.

In June 2011, the Georgia Bureau of Investigation released evidence of test tampering at 44 Atlanta schools, including Venetian Hills. Armed with subpoena power and threat of criminal sanctions, the investigators secured confessions from five Venetian Hills teachers and the testing coordinator. They also declared that the principal and one other teacher had cheated.

Several Venetian Hills educators said they met in the testing coordinator’s windowless office to alter the answer sheets. One teacher said the coordinator told him they needed to “clean up” the tests, which meant changing the answers from wrong to right. The Georgia report said Clarietta Davis, the principal, “erased answers in her office wearing gloves so that she did not leave fingerprints on the test documents.”

In the District, test security investigators visited J.O. Wilson for the first time on March 22 of this year. The team from the consultant firm Alvarez & Marsal conducted seven interviews, but its report did not mention the school’s erasures. Instead, it focused on test procedures and concluded “we found no potential testing violations at this school.”

The D.C. Inspector General’s office, the third organization asked to check on alleged D.C. cheating, reported last month that it would not investigate test tampering at J.O. Wilson, in part because D.C. Schools Chancellor Kaya Henderson assured them it was a great school. It did not note that proficiency rates at the school had dropped sharply — 37 percentile points in math and 26 percentile points in reading by 2012 — after security was tightened, another indication of tampering identified in Atlanta but not in the District.

What would have happened if D.C. officials had taken the erasures at J.O. Wilson as seriously as Georgia officials did at Venetian Hills? Would a timely investigation have discovered flagrant dishonesty, the kind that hurts students by giving them and their parents false hopes of progress? We know what a thorough investigation found in Atlanta.