Minneapolis Public Schools officials and the teachers union went back to mediation Thursday in search of contract agreements to end the strike that has shuttered classrooms across the city.

The parties also met for 90 minutes Wednesday.

The union is seeking pay raises for teachers and education support professionals, class-size caps and additional mental health supports for students, among other things.

Superintendent Ed Graff has said the parties are "very far apart" and that the cost of the union's proposal is $166 million over the district's budget.

Union leaders said no progress was made in Thursday's mediation sessions, and they'll be back at the table on Friday.

"We are here to tell them we aren't moving," said Shaun Laden, president of the educational support professionals chapter of the Minneapolis Federation of Teachers, on Thursday before heading into mediation. "Our members are determined — we have to make systemic change in our district if we are going to turn this thing around."

Earlier in the week, Graff said he was "frustrated, sad and concerned" about the strike.

The immediate need, he said, is to find a way to end the strike and get students back in school. The long-term issue, he said, is to find solutions to the district's budget challenges — Minneapolis Public Schools has projected a $21.5 million budget shortfall next year, despite the use of $75 million in one-time federal relief money.

Negotiations dragged on for months, and teachers filed their intent to strike in late February. The strike began Tuesday and educators have been picketing at schools and around the city each morning and holding rallies each afternoon.

The district's 28,700 students will not attend school until the strike concludes. Families, for the most part, have had to find their own child care in the meantime.

More mediation sessions are scheduled for Friday, Saturday and Sunday.