CHICAGO (AP) — The Chicago Teachers Union said Sunday that its members voted to defy an order to return to the classroom over concerns about COVID-19, setting up a showdown with district officials who have said that refusing to return when ordered would amount to an illegal strike.

Chicago Public Schools, which is the nation's third-largest district, wanted roughly 10,000 kindergarten through eighth grade teachers and other staffers to return to school Monday to get ready to welcome back roughly 70,000 students for part-time in-school classes starting Feb. 1. No return date has been set for hi...