PITTSBURGH — Seven Democratic candidates for president on Saturday offered plans to make their mark on U.S. schools.

Although the vast majority of education decisions are made at the state and local levels, candidates who participated in a forum sponsored by 11 education groups vowed to increase federal spending in schools — some by enormous amounts — and proposed other ways to make schools more equitable and to support teachers, students and parents.

The six-hour forum at a downtown convention center, moderated by Ali Velshi, host of "MSNBC Live," and Rehema Ellis, an NBC News education correspondent, streamed live on NBC News Now, MSNBC.com and NBC News Learn.

Each candidate spoke for 25 minutes, fielding questions about K-12, early childhood and higher education from the moderators and members of the audience, made up of more than 1,000 students, parents and community members.

The event, one of the first times public education has been the focus of the 2020 presidential race, featured Sen. Michael Bennet of Colorado, former Vice President Joe Biden, Mayor Pete Buttigieg of South Bend, Indiana, Sen. Amy Klobuchar of Minnesota, Sen. Bernie Sanders of Vermont, California businessman Tom Steyer and Sen. Elizabeth Warren of Massachusetts. An eighth candidate, Sen. Cory Booker of New Jersey, had planned to participate but canceled on Friday when he came down with the flu.

Sen. Bernie Sanders, I-Vt., one of seven Democratic candidates participating in a public education forum in Pittsburgh, makes opening remarks. Keith Srakocic / AP

Watch it here. These were some of the highlights:

Charter schools — outside

People arriving for the forum Saturday morning were greeted by more than 100 charter school parents, educators and advocates who protested under umbrellas in the rain.

Supporters of charter schools, which are publicly funded but privately managed, say they have concerns that some candidates, notably Warren and Sanders, have called for cutting federal funding for new charter schools and restricting their growth. Warren and Sanders say charter schools draw money from traditional school districts and aren't subject to the same rules.

Some of the candidates "have not included charter schools for the most part in a positive way in their platform," said one of the protesters, Sonya Toler, who works for the 13-school Propel charter network in Pittsburgh.

Those candidates might be courting the votes of large unions like the American Federation of Teachers, which was one of the sponsors, Toler said, but "they can't forget the vote of the people who work and send their children to our schools."

"They vote as well," she said. "Charter schools need to be a part of their platform."

The protesters said they were excluded from the forum and not allowed to question candidates. Organizers said charter school backers would have been included if they had asked. Toler said she did ask but was rebuffed.

Charter schools — inside

Charter schools make up just 7 percent of public schools, but they still drew a lot attention.

Warren interrupted a moderator who suggested that she wanted to "cut off funding" to charter schools.

"I'm not sure I'd call it cutting off," she said, saying she doesn't want to stop funding to existing schools. "What I believe is that public school money needs to stay in public schools."

Charter schools are public schools typically required to admit students through a lottery, including those with disabilities. Their students have the same standardized testing requirements as other public schools, but in some parts of the country, the schools are run by for-profit management companies. Even those run by nonprofits aren't always subject to open-records laws and other regulations that apply to government agencies.

Warren has been confronted on the campaign trail by charter school parents who say charter schools give a choice to low-income parents who don't have the option to move their children to a private school, as Warren did when her son was in the fifth grade. Warren said she was sensitive to those parents' concerns.

"They're looking for the best educational opportunities for their children," she said. "But I believe it is our responsibility as a nation to make certain that every public school is an excellent public school."

Other candidates said they supported charter schools but wanted them held to higher standards.

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Bennet said he oversaw charter schools when he was schools superintendent in Denver, where they are held to the same standards as district schools.

"I'm not saying it's perfect, but it's a heck of a lot more perfect than almost any other area," he said.

He singled out Detroit, where he said schools have been negatively affected by policies supported by Education Secretary Betsy DeVos, a philanthropist who helped expand charter schools in Michigan, her home state.

After the forum, Bennet retweeted a picture of himself meeting with pro-charter activists.

Buttigieg, who has been less critical of charter schools than some of his opponents, has joined them in calling for tighter rules. He fielded questions after the forum about a fundraiser being hosted for him by Netflix Chief Executive Reed Hastings, a prominent charter school donor.

"There are 700,000 donors to my campaign. Some of them may disagree with me on some of those issues," Buttigieg said. "But my stance will not change, including my support for teachers and my support for labor."

They want to spend more money — a lot more

Much of the media attention on education has focused on how candidates want to lower the cost of college and reduce or eliminate college debt. Those issues came up on Saturday, as did a host of spending proposals to give children the kind of education that would help them succeed in college.

Sanders, Biden and Buttigieg said they wanted to triple funding for Title I, the government's main program for schools that serve children from low-income families. Warren said she wanted to quadruple the funding.

Candidates said the extra money could address a host of educational challenges, including teacher pay and the hiring of support staff, such as school psychologists.

Warren dismissed a question about how to make the formula that the government currently uses to distribute TItle I dollars more equitable, saying she wanted to put so much money into the program that how it was distributed wouldn't be an issue.

"The question is not how do we take what we currently spend at the federal level and move it around," she said, adding that the government needed to "invest what it takes to create a quality opportunity for every one of our children."

Several candidates also called for funding early childhood education, with some calling for preschool to be free for all 3- and 4-year-olds and others calling for it to be free for children from needy families.

"If you had $10 to spend and that's all you had to spend on education, I'd spend 7 of them on preschool," Biden said.

But Title 1 isn't the only federal programs the candidates suggested boosting.

Klobuchar said she would help schools but also work to improve affordable housing, arguing that fewer homeless children would put less burden on schools.

Asked whether the government should expand the free lunch program to all children so no one was "lunch shamed" for being unable to pay for a meal, Sanders responded: "You know what? And breakfast and dinner, as well."

Several candidates offered ideas to make schools less segregated in response to recent studies showing that, six decades after the Supreme Court's landmark ruling in Brown v. Board of Education, U.S. schools are increasingly racially segregated.

Sanders, who said his elementary school class in Brooklyn had just one black student, said more money would be one solution. He also vowed to beef up the Education Department's Office of Civil Rights to investigate violations.

Biden, who was taken to task by Sen. Kamala Harris of California (who has dropped out of the race) during a debate last summer for his opposition to school busing in the 1970s, seemed flustered when asked about segregation at the forum, but he asserted that he was "extremely proud" of his civil rights record.

"It's as good or better than anybody in politics," he said.

Most of the candidates played up their personal connections to education, highlighting spouses and parents who worked in schools. Biden spoke of his experience with teachers who helped him as a child with a stutter.

"I had teachers who first and foremost worked on my confidence, told me I was smart, told me I could do what I needed to do, sat with me and gave me the confidence to stand up and try to speak," he said.