LOS ANGELES — Using a microphone to project her best teacher voice, Assistant Principal Ivania Holodnak attempted to control a room full of 170 fidgety middle-schoolers at Vista Middle School crowded shoulder to shoulder at long cafeteria tables.

“Vaqueros y vaqueras,” Holodnak said, addressing the students by their school mascot. “We’re going to do the clap-clap-hand!”

Most of the students complied, clapping twice and then putting their hands up. It was one of the tools Holodnak used to keep order, with help from parent volunteers and classroom aides, while she had students explain quotes from the Rev. Martin Luther King Jr. in their own words.

“We’re giving you all a little bit of that college experience!” Holodnak said, explaining they might someday take a class in a lecture hall with just as many classmates.

Tuesday marked the second day of a teachers strike in the Los Angeles Unified School District. The strike affected about 600,000 students, who are overwhelmingly poor and children of color: Nearly 75 percent are Latino and 8 percent are African American. About 82 percent of all students qualify for free or reduced-price lunches, and the district serves about 1 million meals each school day. Nearly 16,000 students are homeless.

As the school system remained at a stalemate with United Teachers Los Angeles — the union representing the 30,000 striking teachers — administrators, parents and students grew more eager for their return.

Teachers walked off the job after a months-long impasse in contract negotiations with the district and Superintendent Austin Beutner, a former investment banker and nonprofit executive who had no experience in education. Beutner and the board that hired him — a majority of members were elected with the help of charter-school backers — is distrusted by the union, which believes he is trying to privatize the district by allowing charter schools to proliferate.

‘As long as it takes’: Los Angeles teachers go on strike in nation’s second-largest system

The teachers’ demands focus mostly on classroom resources: They want the school system to hire more educators to reduce class sizes, which have ballooned to more than 35 in many schools. And they want more counselors, librarians, nurses and psychologists. They worry that further cuts will prompt more students to leave the traditional school system for independent charter schools, which are privately run but publicly funded.

On Tuesday, thousands of teachers rallied in the rain again, this time outside the offices of the California Charter Schools Association in Los Angeles.

Beutner on Tuesday morning reiterated that the district cannot afford the union’s demands.

“Nobody wishes more than I that we can do that,” Beutner said. “But the painful truth is we don’t have the money to do everything UTLA is asking for.”

Many students opted to stay home during the strike, citing a host of reasons. With so few adults in the schools and so many students, some families worried about safety. Others wanted to back the union or simply did not see the benefit of attending school when classrooms are largely bereft of teachers.

On Tuesday, Beutner said nearly 160,000 students attended school. Because the state allocates money based on how many students show up, the superintendent estimated the district lost about $25 million Monday, but saved $10 million because striking teachers were not getting paid.

Students who showed up for class found situations akin to what unfolded at Vista Middle, with children sometimes shoehorned into gyms and auditoriums, and overwhelmed administrators doing their best to keep students interested and engaged. The middle school grouped all students together by grade, meaning classes averaged more than 100 students. During lunch, some girls wandered toward the library but were turned away because the librarian was on strike.

Principal Joe Nardulli said the school, where nearly all students come from low-income households, strives to give children challenging classes. It hosts a sports medicine magnet program, and gifted students can take community college classes for credit. When the strike is over, he anticipates the school will need to have weekend sessions so students can catch up.

Angela Papazian, 11, said she still enjoyed being at school, but she missed her teachers. They explained to her why they might be absent this week, and she backs their fight.

“I honestly think that it’s okay, because they’re fighting for us and they’re fighting for an important thing,” Angela said.

Ari Bennett, an official with the school district who oversees Vista Middle and 10 other schools, was on campus Tuesday helping the administrators and teacher aides run activities, hoping to stimulate students’ minds. It was better, he said, than if they were home playing video games or watching movies.

But, he added: “It can never be the same without the teachers.”

Susan Montes Deoca, a special-education aide, leaned against the wall of the gymnasium while middle schoolers played soccer. More than 100 of their classmates were seated in the stands, waiting their turn to play. Montes Deoca noted the irony in the teachers’ fight for smaller class sizes. By striking, they had temporarily achieved the opposite.

“It’s very hard,” Montes Deoca said. “I understand that teachers are fighting for smaller class sizes. This is an example of needing smaller class sizes. There’s hundreds of kids in only three classes.”