Teachers and their supporters staged the latest in a recent series of Boston public schools protests before classes Friday morning, marching in “walk-in’’ demonstrations across the city.

The actions were organized by the Boston Teachers Union to call on the school department to speed contract negotiations and back down on some of the district’s most controversial proposals. Participants also expressed frustration with a variety of other issues.

Amy Sicairos, a first-grade teacher at Roslindale’s Charles Sumner Elementary School who has taught in Boston for 23 years, counted deteriorating buildings, over-capacity classrooms, excessive time spent on standardized testing, and ever-rising standards among her concerns.

“It’s really difficult to do with the conditions we’re being given,’’ Sicairos said.

Sicairos was among about two dozen teachers who marched with students out of the Sumner and into nearby Roslindale Village, chanting “We believe in BPS!’’ and toting signs with messages including “Save our public schools!’’ and “Fighting for English Language Learners! Join us!’’

“We just want to send the message that our schools are important,’’ said Louie Bello, the Sumner’s music director. “I think it’s getting lost in all the political nonsense that’s been going on. It’s about the kids.’’

A district spokesman said the school department is working closely with the union to provide a contract that benefits both teachers and students before the current agreement expires Aug. 31.

“It is important that our teachers advocate for what they care about,’’ said the spokesman, Richard Weir. “The BTU and its members are passionate about education in Boston, just as we are in the school district.’’

Teachers staged another walk-in last month, and students led protests in February, March, and May to oppose proposed cuts to next year’s school budget. Days after the March protest in which about 3,650 students — mostly from the city’s high schools — walked out of classes, Mayor Martin J. Walshrestored about $6 million to high school budgets.

Earlier this week, after the City Council rejected Walsh’s proposed city budget, he added another $5 million to education spending.

At least 3,000 teachers and aides participated in Friday’s protests at about 106 of the city’s 125 schools, according to Richard Stutman, president of the teachers union.

Jeremy C. Fox can be reached at jeremy.fox@globe.com. Follow him on Twitter @jeremycfox.