As the Newtown, Ct., horror unfolded last Friday, dozens of news sources reported a striking element of the story: that Nancy Lanza, mother of shooter Adam Lanza, was a teacher at the school where her son killed 26 people before killing himself, the Washington Post reports. This account persisted — in news reporting and in conversation — and seemed to fill in a critical element of the tragedy: a motive. She was not a teacher, a substitute or a teacher's aide at Sandy Hook Elementary School, as some reported. Other accounts said incorrectly that she had been killed at the school along with her students.