By Michael Pearson and Holly Yan, CNN
(CNN) - Chicago public school teachers began manning picket lines instead of classrooms Monday, launching the first teacher strike in the city in 25 years over pay, benefits and other issues.
The strike, announced Sunday night, left about 350,000 students without a school to attend and parents scrambling to find alternatives.
The school district has opened 144 of its 578 schools for part of the day to provide a safe environment and meals to children in need. Also, dozens of churches and civic organizations have stepped into the vacuum to provide activities for the thousands of suddenly idle students. And police, expecting an uptick in trouble from kids on the streets, pulled officers from desk duty to increase patrols.
The union that represents nearly 30,000 teachers and support staff in the nation's third-largest school district called the strike after negotiators failed to reach a contract agreement with school administrators despite 10 months of negotiations.
Teachers say the biggest issues leading to the impasse are maintaining their health benefits and job security, as well as improving classroom conditions.
As many as 6,000 teachers could lose their jobs under a new evaluation system based on standardized test scores implemented by the school district, Chicago Teachers Union President Karen Lewis said.