ATLANTA (AP) — A few weeks into the new school year, growing numbers of U.S. districts have halted in-person learning or switched to hybrid models because of rapidly mounting coronavirus infections. The setbacks in mostly small, rural districts that were among the first to go back are dampening hopes for a sustained, widespread return to classrooms after two years of schooling disrupted by the pandemic. More than 80 school districts or charter networks have closed or delayed in-person schooling in at least one entire school in more than a dozen states. Others have sent home whole grade levels or asked half of their students to stay home on hybrid schedules.