As the highly infectious Omicron variant surged, a high-stakes battle played out between Mayor Lori Lightfoot of Chicago and the city’s teachers’ union about how to keep schools open and safe.We chart this battle on the ground in Chicago, speaking with teachers, parents and students about the standoff.Sign up here to get The Daily in your inbox each morning. And for an exclusive look at how the biggest stories on our show come together, subscribe to our newsletter. Background reading: The deal between the city and the teachers’ union included provisions for additional testing and metrics that would close schools with major virus outbreaksAs millions of U.S. students headed back to their desks, the coronavirus testing that was supposed to help keep classrooms open safely was itself being tested. In much of the country, things are not going well.For more information on today’s episode, visit nytimes.com/thedailyTranscripts of each episode will be made available by the next workday.