The threat of a strike in the nation’s second-largest school district comes nearly a year after a teacher walkout in West Virginia set off a wave of union activity nationwide.

Here’s what you need to know:

Where do negotiations stand?

After a year and a half of negotiations and talks ending in a stalemate on Monday, a successful outcome seems unlikely; nevertheless, the United Teachers Los Angeles (UTLA) and the Los Angles Unified School District are scheduled to meet again on Wednesday in a last-ditch effort to avert the strike.

In addition to ongoing negotiations, the district has claimed that the union did not provide the requisite 10-day notice that its members would stop working under their existing contract in an attempt to thwart the strike. The L.A. Superior Court judge has postponed the hearing on the matter until at least Wednesday, but should it rule in favor of the district, the union will be compelled to postpone the strike for a minimum of 10 days.

Should the strike go forward, however, around 32,000 teachers and staff members are expected to participate, affecting the district’s 600,000 students. Classes are due to take place regardless of the strike.

Ronen Tivony—NurPhoto via Getty Images

What are the teachers asking for?

In part, the union wants better salaries a little sooner. The district has offered a 6% raise spread over the first two years of a three-year contract; the UTLA wants 6.5% and all at once, at the end of the first year of that contract.

But the majority of the teachers’ complaints concern the services the school district is providing to its students. The union wants the district to start spending its $1.9 billion reserve to reduce class sizes and hire more nurses, counselors, and librarians. They also want to open a conversation about the standardized testing that happens in the district, and whether it’s the appropriate amount.

The union also argues the strike would be good for the future of education.

What does the district want?

The school district, led by superintendent Austin Beutner, also wants to do right by the district’s students. In Beutner’s view, that means not having a strike. It also means not overspending the district’s resources, which he says the teachers’ union’s proposals would require.

Poised for a fight

The teachers’ union appears ready and willing to walk out on Thursday if they don’t reach a satisfactory agreement with the district.

For its part, the school district is not taking the threat of a strike lying down. They’ve hired 400 non-union substitute teachers to break the picket line if necessary, and even tried to get a federal judge to prevent the strike, arguing it would interfere with services to special needs students, which are guaranteed by law. That argument was rejected.