Rajendra Dawadi was inside his classroom when a colleague rushed in with a warning: floodwaters were racing through Nepal’s Trishuli Valley, tearing apart homes, bridges and entire villages.Then a teacher received another warning by phone. Moments later, a parent arrived to take her child home. The danger had not yet been confirmed, but Dawadi, the principal, had little time to act. He rang the school bell and ordered his students and staff out of the building and towards higher ground.“I...