For 10 years, hundreds of Atlanta public school teachers and principals changed answers on state tests in one of the largest cheating scandals in U.S. history, according to a scathing 413-page investigative report released Tuesday by Georgia Gov. Nathan Deal, Yahoo! News reports. More than three quarters of the 56 schools investigated cheated on a 2009 standardized state test, with 178 educators implicated, including 38 principals. Eighty-two teachers confessed to erasing students’ answers and correcting tests…