CHICAGO (Reuters) -On a chilly morning outside Nash Elementary School in a working-class Chicago neighborhood, teachers greeted students with the usual high-fives and hugs, while handing out sheets with red-bolded words proclaiming in capital letters: “Defend your rights under the threat of occupation.” Four weeks into President Donald Trump's "Operation Midway Blitz" deportation drive, mass arrests across the city - which have swept up parents on their way to school and entire families - have induced fear in immigrant communities and protectiveness from educators, according to city leaders, the teachers' union, parents and immigration advocates. "My Latino students, they're fearing...