D.C. Public Schools have come a long way since the days when administrators used after-school program funds for vacations, money for textbooks and school repairs routinely disappeared, and thieves helped themselves to school cafeteria food right off the loading docks. But there are troubling signs that elements of the culture of corruption that robbed generations of District children of a quality education are still around. A probe by D.C. Attorney General Irvin Nathan into McKinley Technology High School’s alleged misuse of a $100,000 AARP award led investigators to a much more serious accusation: grade tampering by McKinley principal David Pinder, who was brought in from Baltimore by former schools Chancellor Michelle Rhee. Transcripts obtained by The Washington Examiner’s Lisa Gartner showed Pinder listed as the “teacher” of at least 13 McKinley seniors, even though he never taught a class. School data clerks also said Pinder ordered them to assign some seniors bogus credits for courses they never took, presumably as a way to maintain McKinley’s coveted 96.5 percent graduation rate — the second-highest in the city.