This year alone has seen teacher-cheating scandals in Washington, D.C., Los Angeles, Atlanta, and elsewhere; in this week's Times, Sharon Otterman reports how New York State is trying to curtail cheating and offers some specific instances of past cheating:

A charter school teacher warned her third graders that a standardized test question was “tricky,” and they all changed their answers. A high school coach in Brooklyn called a student into the hallway and slipped her a completed answer sheet in a newspaper. In the Bronx, a principal convened Finish Your Lab Days, where biology students ended up copying answers for work they never did.

This comes as little surprise to Steve Levitt, who several years ago recognized what most legislators and school administrators were unable (or unwilling?) to foresee: that the introduction of high-stakes testing would create incentives that might encourage some teachers (especially bad ones) to cheat on behalf of their students. So he developed an algorithm to catch cheaters, which was so successful that then-Chicago schools chief Arne Duncan brought Levitt in to help identify and fire cheating Chicago teachers.