Public schools across Woburn are poised to close for a second day on Tuesday after negotiations between city officials and the teachers union deteriorated.

Barbara Locke, president of the teachers association in the small city north of Boston, said pay raises for teaching assistants was a major point of contention.

“We cannot teach without them in our classrooms,” she said. “We need to pay them better. We need to respect and value them. That’s primarily what this is about.”

Woburn Mayor Scott Galvin and Woburn School Committee members did not respond to requests for comment. The state requested an injunction at the request of city officials in an effort to end the strike.

It’s illegal for teachers to strike in Massachusetts, and unions that do so can face hefty fines.

Unsuccessful negotiations ran for eight hours on Sunday and continued on Monday as educators picketed outside the high school. About 100 teachers and supporters picketed in front of the high school on Monday morning, chanting “C-O-N-T-R-A-C-T” and singing along to Twisted Sister’s “We’re not going to take it.”

The teachers union said it has asked for higher teacher and paraprofessional wages, compensation for unpaid duties and smaller class sizes. Educators in Brookline, Haverhill and Malden, have made similar demands and gone on strike in the last year.

The Brookline and Malden teachers’ strikes both ended after one day. In Haverhill, the strike lasted four days. The Massachusetts Teachers Association, the state’s largest teachers union, is seeking to change the law making teachers’ strikes illegal in Massachusetts, saying it helps push both sides toward an agreement.

Woburn history teacher Eric Scarborough, the union’s deputy secretary, said teachers would rather be doing their job instead of picketing.

“We got to a point where we felt like we couldn't go any further,” he said. “They’re not offering us a contract or listening to our proposals or compromising.”