McLoughlin Middle School eighth-grader Brynn Allen sees it simply: If students feel welcomed at her school, they’ll want to come to it. “Sometimes people have rough lives and school is their escape,” she says, recalling a phase in seventh grade where she was struggling personally. “It kind of felt like everyone was there. It was like a welcoming center.” School culture may be harder to quantify than academic achievements, but McLoughlin leaders say thought, heart and data spurred their...