On Wednesday, March 14, eight days into a new job teaching biology at Sisters High School, Kris Helphinstine showed a class of freshman and sophomore students pictures of naked corpses, a Nazi swastika and Charles Darwin in a PowerPoint presentation. "What do these pictures have in common?" the 27-year-old part-time teacher asked the 30 students. They listened as Helphinstine gave a roughly hourlong presentation, explaining how the Third Reich perverted evolution and eugenics to slaughter Jews and Gypsies in death camps to protect the "superior race." On the Monday and Tuesday before giving the PowerPoint presentation, Helphinstine had given the...