I WENT Friday morning to see “Selma” and found myself watching it in a theater full of black teenagers.Thanks to donations, D.C. public school kids got free tickets to the first Hollywood movie about the Rev. Dr. Martin Luther King Jr. on his birthday weekend — an effort that was duplicated for students around the country. The kids did plenty of talking and texting, and plenty of fighting over whether there was too much talking and texting. Slowly but surely, though, the crowd was drawn in by the Scheherazade skills of the “Selma” director, Ava DuVernay. The horrific scene...