Kendrick Castillo and his father John, in their blue Knight of Columbus aprons serving at a pancake breakfast. Denver, Colo., / When Sara Haynes heard about the shooting at STEM High School in Highlands Ranch, Colorado on Tuesday, she prayed. A Catholic school teacher in Denver until just recently, she knew some of her former students were now high schoolers at STEM. When Haynes learned that Kendrick Castillo, a former student of hers, was the lone casualty in the May 7 shooting, she cried immediately. Then she reached out to the other students who had been in the same...