With a bold and passionate show of force for education, tens of thousands of protesters took to streets and campuses across California on Thursday in a day of action: They shut down UC-Santa Cruz, interrupted lectures with megaphones at UC-Berkeley, filled high school auditoriums in San Jose and daringly blocked rush-hour freeway traffic in Oakland.

The rallies, held from Humboldt to San Diego, drew enormous but mostly peaceful and diverse crowds — from kindergarten kids to Ph.Ds — united by a single message: Save public education.

They decried budget cuts that have forced fee hikes at the state’s universities and crowded classrooms at all grade levels.

“It’s the death of the future success of our children,” said San Mateo seventh-grade teacher Aura Smithers, who carried a symbolic coffin through the throngs marching in San Francisco’s Civic Center Thursday evening. “I know it’s a real tough economic time, but cutting education is just going to be more detrimental to our communities, to our society and to our state as a whole. Enough is enough.”

To cut costs, schools have truncated the number of classes offered, furloughed teachers and cut everything from clubs to counseling. Even more severe financial trouble is on the horizon as schools drain federal stimulus money.

“We’re losing classes,” said San Jose State student Lauren Gray, 22, who protested during lunch hour and then rushed off to a psychology lecture. “I’m a senior and I won’t be able to graduate in time.”

Experts — confirming protesters’ concerns — say the long-term effect of the current funding crisis could be far more expensive to the state if California loses its educated work force. Continued cuts, according to a recent report by the California Postsecondary Education Commission, will threaten the future of a state that has long prided itself on brains and innovation.

“Public education drives a society’s ability to progress and to prosper,” UC President Mark Yudoff said in support of the rallies.

Thursday’s March 4 Day of Action was organized at UC-Berkeley but then expanded nationally with similar rallies in states across the nation where the economic downturn is also stressing state budgets and triggering education cuts.

While boisterous rallies last fall raised the call for college funding, Thursday’s protest included new faces. A group of six San Jose State Unified School District classified workers joined the protest in San Francisco to make sure the voices of support staff were heard. The decline of bus drivers, cafeteria workers, classroom aides and secretaries have created real hardship for children in poorer districts, said Robin Hill, a San Jose office technician.

Cristina Ruotolo, associate professor of humanities at San Francisco State University, said she is teaching 75 students in classes that once had 55. The increase means less participation in classroom discussions and fewer graded assignments.

“Sometimes there aren’t even enough chairs in the room,” Ruotolo said.

At state universities, students fees have grown almost 50 percent higher since 2007, while thousands fewer classes are being offered, according to the California Faculty Association. But with record numbers of applicants, this year, Ruotolo said, coming together on Thursday felt gratifying. “A lot of us used furlough days to be here,” Ruotolo said.

At San Jose State University students squeezed in their protest during lunch hour, so they wouldn’t miss classes.

Their theme — “Keep The Doors Open!” — focused on reductions in classes and teachers, causing students to worry that they won’t be able to get their degree.

Students first gathered at City Hall, where professor Jonathan Karpf addressed the crowd: “Here are the ground rules: There will be no vandalism. There will be no confrontation. We will stay on sidewalks. We will be orderly, civil — and loud.”

Then a crowd of 650 marched along sidewalks to San Jose State’s Tower Lawn, stopping by Room 206 at the Paseo De San Antonio Walk. There they covered the office door of Sen. Abel Maldonado — a moderate Republican who could be influential — with “Please Support Education!” letters and chanted “Abel Maldonado, We Need Your Support!”

Protests were more raucous in Oakland, Santa Cruz and Davis.

During rush hour more than 150 people were taken to jail for blocking the I-980 and I-880 freeway, Oakland police said.

Northbound and southbound Interstate 880 were clogged as officers removed protesters who hopped onto the freeway earlier. One protester was taken to the hospital after falling from a tree.

At Davis, protesters clashed with police, who fired bean bags, tear gas and pepper spray, as protesters locked arms and tried to block Interstate 80, according to The California Aggie, the campus newspaper.

In Sacramento, students, teachers, parents and school employees from across California rallied at the Capitol to urge lawmakers to restore funding to public schools.

In Southern California, the largest event was in downtown Los Angeles’ Pershing Square, where busloads of demonstrators arrived from across the region. Police estimate 500 people gathered at UCLA’s Bruin Plaza.

University leaders praised the movement but warned that sustained pressure on Sacramento will be needed.

“These are students or union workers who have a stake in the game,” UC spokesman Peter King said as he watched the downtown Oakland demonstration. “The greater movement will be when you see Californians who don’t yet know they have a stake participating.”

Hundreds packed San Jose’s Independence High School, where Assemblyman Joe Coto said he will seek more new taxes on oil, entertainment, soda pop, golf, skiing and chartered private jets. He also supports an initiative to overhaul the two-thirds majority needed for new taxes.

“California is not a tax-heavy state,” he told the Mercury News. “We need to broaden the tax base, look at corporate loopholes and maintain the vehicle license fee. There are a number of ways to approach the issue.”

California’s pain isn’t unique. Nationally, state support for higher education is falling and federal subsidies in many states will soon be exhausted. Protesters rallied in Alabama, Texas and Wisconsin, where they threw punches and ice chunks. More than 25,000 students there have been put on a waiting list after the state’s premier financial aid program ran out of money.

As San Jose State students ended their protest, SJSU administrator Fred Najjar assigned some homework: “We’re not done. Go to Sacramento. Go write letters to our elected representatives. It is not just about today, it is about the future of our work force and economy.”

Then, the crowd dissolved — and students hurried to class.

Mercury News staff writers Lisa Fernandez, Mark Gomez, Bay Area News Group reporters Matt Krupnick, Neil Gonzales, Megha Satyanarayana, the Associated Press and Los Angeles Times contributed to this report. Contact Lisa M. Krieger at 408-920-5565.