"When I knocked at the door," recalls Carlos Rivera, 36, who supervises elementary Spanish in the El Paso public schools, "I repeated several times, 'Pase usted,' but I did not enter." The door led to a first-grade classroom filled with tots, few of whom spoke Spanish. They had been told only that their expected visitor "understands English, but does not speak it." The children soon grasped the meaning of Rivera's phrase ("Enter"), and repeated the invitation to come in. Rivera smiled and walked in with a greeting: "¡Buenos dias, niños!"
Since that September morning in 1951, when El Paso began its...