Tens of thousands of teachers went on strike Monday in Los Angeles, California. The teachers acted after contract negotiations failed. "Students, we are striking for you," said teachers union President Alex Caputo-Pearl. He spoke to a cheering crowd of teachers marching in the rain. Los Angeles is the second-largest school district in the United States. Members of United Teachers Los Angeles voted last year to call a strike if the union and school district failed to reach an agreement. The teachers want higher wages and smaller class sizes. Months of negotiations between the two sides ended without a deal. It follows teacher strikes in other states. The union has 35,000 members. Schools are open in the Los Angeles Unified School District, which serves 640,000 students.