Nearly all of us have taken bubble tests. We mark the spaces with a soft pencil. Occasionally we make a mistake, erase the mark and fill in the right bubble. On average we make no more than two or three changes per test, experts say.

That is not what has been happening in the annual standardized tests given in the D.C. schools, according to the story by Jack Gillum and Marisol Bello that concludes USA Today’s series “Testing the System.” They reveal that the D.C. schools have been winning awards for test results in which there are so many wrong-to-right erasures---averaging more than a dozen per student in some classes---that the odds of that happening by chance are worse than for winning the Powerball lottery grand prize.

The possibility of cheating by administrators or teachers reacting to rising pressures for test success is obvious, but the newspaper has discovered that D.C. school officials tried to prevent an in-depth investigation and refused the newspaper’s request to visit schools and talk to staff.

I have a bias about the USA Today series, which involved 13 reporters. My wife, senior projects editor Linda Mathews, conceived and edited the investigation of possible cheating on standardized tests in schools across the country. Readers who don’t trust my objectivity on this should just go straight to the articles and make up their own minds.

There is too much there to brush off as happenstance or the result of legitimate if unusual test-taking methods, as D.C. officials have been trying to do. I think the series’ revelations will force a turning point in the national debate over raising school achievement.

People like me who have applauded former D.C. schools chancellor Michelle A. Rhee and other leaders for taking test results seriously are going to have to reject achievement gain data as meaningless unless it comes with the kind of tampering analysis used by USA Today. D.C. school administrators had such analysis before them but failed to investigate with much care the schools identified as having too many erasures, and did not release the details to the press, or even to the parents of the children affected.

Since 2008 in the District, USA Today reported, 103 schools have been flagged at least once because their erasure rates far surpassed D.C. averages. A trio of academicians consulted by USA TODAY—Thomas Haladyna of Arizona State University, George Shambaugh of Georgetown University and Gary Miron of Western Michigan University—say such erasure rates are so statistically rare that they should be investigated.

In 2008, state superintendent of education Deborah Gist recommended that several D.C. charter schools and regular D.C. public schools be investigated to find out why their erasure rates were so high. Seven of the charter schools complied but D.C. school leadership, representing the regular schools, resisted.

The concluding story in the series focuses on Noyes Education Campus, which has pre-school through eighth grade students in northeast Washington. Its test score increases led to its designation as a National Blue Ribbon School by the U.S. Education Department in 2009.

Gist submitted two lists of schools to be investigated, each list based on a different statistical method for identifying examples of high wrong-to-right erasures, the newspaper said. Even on the list that took the more conservative approach, Noyes recorded a rate of corrected answers on a reading exam of 12.7 per student, 15 times higher than the D.C. average. .

If an investigation confirms that those erasures did not have had an innocent cause, I think Education Secretary Arne Duncan should take back the school’s blue ribbon award. That apparently has never been done before. The novelty of his decision might persuade school districts to get serious about how they handle testing.

D.C. officials justified their decision not to launch an investigation in 2008 by quoting a memo from the testing company CTB McGraw-Hill saying that officials “should not draw conclusions about cheating behavior” from the data analysis. When USA Today obtained the full text of that memo through a Freedom of Information Act request, it found that the McGraw-Hill analyst had also said the data could be properly used to identify “possible cheating incidents for follow-up investigation.”

Mary Lord, a member of the state board of education for the District, told the newspaper that the board’s members were not aware of the dispute over investigating schools with high erasure rates until months later when it was first reported by my Washington Post colleague Bill Turque. She said she had never seen the actual 2008 erasure analysis with the list of schools flagged by McGraw-Hill until the USA Today reporters showed her the copies they had obtained through their investigation.

School administrators resisted inquires not only from journalists but from parents, USA Today reported. Marvin Tucker, a Noyes parent, said even before the test erasure controversy he was asking questions about the discrepancy between his daughter Marlana’s high test scores and her struggles at home with arithmetic. Noyes principal Wayne Ryan, who later appeared in D.C. school recruitment ads as one of the system’s “shining stars” because Noyes test scores soared, banned Tucker from the school campus for a year when he complained too much, Tucker told USA Today. Tucker said Ryan accused him of threatening members of the school staff, which Tucker said was not true.

The expert opinion on the suspicious nature of large numbers of wrong-to-right test erasures should be enough for any administrator to order an investigation and publish the results. Many parents use test score data to select the best school for their children. They deserve the facts.

I think most of us who have taken bubble tests don’t need experts to see the problem. We answer the questions as best we can, go over our answers and maybe change a few. The key question is: Under what innocent circumstances would we ever change eight, nine or 10 of our original answers, and make the correct wrong-to-right choice every time?

The only instance I can think of is if we discovered we were on the wrong row of the answer sheet, not something that is going to happen to dozens of school children in different classrooms on the same test.

As for less savory explanations, if I had no moral qualms, I can imagine making that many wrong-to-right changes when someone told me the correct answers in the middle of the exam. The USA Today series has shown that attempts to do that in other parts of the country have often been detected because students, as bothered by cheating as anyone else, went home and told their parents, who reported it to school headquarters.

I am not saying educators in the District cheated. I don’t know. No one has confessed. But there is enough evidence in what USA Today has uncovered, including procedures that give administrators free access to tests completed by their students, to suggest that adults might have erased wrong answers and filled in right ones after the kids went home.

The D.C. schools should carefully investigate what has happened, as school officials have done in similar cases in Georgia. Whatever those results, school systems should impose better security procedures and better ways of checking test results.

Most of us don’t accept cheating in government contracts, job competitions, or football games. We should be even less willing to accept it when it comes to determining how much our children are learning in school.