Tensions ran high at the United Federation of Teachers Brooklyn office on Tuesday, as union officials volleyed questions, demands, and some cries of exasperation from nearly 100 teachers without permanent positions.

The union office was hosting the second in a series of meetings for members of the Absent Teacher Reserve — the large pool of teachers whose jobs were eliminated when their schools closed or cut costs.

The union is holding the meetings to explain changes to the way teachers in the ATR pool are deployed, based on an agreement struck this summer between the UFT and the Department of Education that stipulates that ATRs must travel to a different school each week. The first weekly assignments are set to start going out today.

But union officials spent much of the meeting deflecting criticism from teachers who charged that the constant upheaval would not make use of their expertise and make them less likely to land permanent positions.

Amy Arundell, a UFT special representative, told the roughly 100 teachers at the meeting that the point of moving teachers weekly is to position them for jobs that could open up at the schools where they are temporarily assigned. The previous arrangement, in which members of the ATR pool often stayed at one school for an entire year, allowed principals to use them as free labor, she said, without necessarily incentivizing them to offer the ATR teachers permanent jobs.

Above frequent interruptions from the standing-room-only crowd, Arundell told teachers they must report to their new assignments next week, even if the principals at the schools they were assigned to for September tell them to stay put. She and several teachers in the room said some principals are asking ATRs to ignore their DOE placements and stay on, in violation of the agreement.

She encouraged the teachers to “be proactive” with the principals and press them to find money in their limited budgets to create permanent positions.

“Otherwise, you can’t stay,” she said. “Unless a principal tells you, ‘I hire you,’ Central DOE won’t know that a principal wants to keep you. You know that saying, ‘Why buy the cow when you can get the milk for free?’ That’s true here.”

That logic sounded hollow for a Manhattan-based teacher who said after the meeting that the normally “pro-teacher” union had agreed to a deal that does not put ATRs’ best interests first.

“This weekly assignment nonsense is meant to aggravate people so they get disgusted and leave,” she said.

During the meeting, attendees called on the UFT to create a chapter just for ATRs and to file a discrimination lawsuit against the city on their behalf. But the union officials present, which included LeRoy Barr, the UFT staff director, rejected those requests, arguing that discrimination is difficult to prove and that chapter leaders at the schools where ATRs are temporarily assigned are equipped to advocate for them.

Arundell urged teachers to contact their temporary chapter leaders with complaints about hostile principals or requests to teach subjects out of their license.

But several teachers complained during the meeting that they had reached out to the UFT and the DOE with complaints, and received no response.

“It may be news for some of you, but there is not union representation in every school,” one teacher called out from the audience. “I was at one school that had no chapter leader.”

Several teachers complained about being assigned by their new principals to lunch duty or clerical work, which Arundell said was not part of their contract. Others spoke of being asked to take on subjects they are not licensed to teach.

One Manhattan-based librarian, who came to the Brooklyn meeting because the Manhattan meeting is not until next week, said her current principal is using her as an assistant to two kindergarten teachers at an elementary school because the school’s library is closed.

“I take the kids to the bathroom every period. That’s about all I do. My principal said to me, ‘I don’t want you here. You’re not going to work anyway.’” She paused for emphasis and whispered, “I think it’s because of my gray hair.”

Teachers throughout the room clapped when one attendee called on the union to file a class-action lawsuit against the city. Union officials shot down the idea, saying that courts require a high burden of proof for discrimination suits that the union would be unlikely to meet.

“But it’s happening everywhere,” another teacher called out. “Stop the shell game that’s taking place.”

Several teachers in attendance said they would like the union to create an ATR teacher chapter to represent them — something the union officials said was not likely to happen.

As the 2.5-hour-long meeting wrapped up, Vincente DeSiano, an elementary school teacher in the ATR pool, collected names and contact information from the roughly 40 people still present, after union officials said they would not provide information about who had attended.

“We have power that we don’t realize,” DeSiano said. “I want us all to be able to share information with each other and see how we can help the situation.”