Teachers in the Chicago Public Schools system, the third-largest school district in the U.S., went on strike on Thursday.
Reuters reports the action came after labor negotiations between the union and district leadership failed to produce a deal.
The strike has canceled classes for 361,000 students, but school buildings stayed open for kids who need a place to go.
Schools will continue to serve breakfast and lunch, but after-school activities have been canceled.
The Chicago Teachers Union is asking for more funding to ease overcrowded classrooms and more support staff.