United Teachers Los Angeles (UTLA) said negotiations stalled and that the union didn't receive a new contract proposal over the weekend, after a strike was delayed from Jan. 10 because of potential court intervention.
Schools won't close, district schools superintendent Austin Beutner tweeted on Monday. The district hired hundreds of substitutes to cover for those on the picket lines demanding higher salaries and lower class sizes in a district that includes about 640,000 students.
The striking educators said they want to remedy classes that often have 40-plus students, a lack of counselors and nurses to support students, closed libraries and crumbling classrooms.
Union members told ABC News they'll strike "for as long as it takes."
