A seismic shift in education is shaking up California classrooms.

Teachers are rewriting lesson plans and rethinking how they run classrooms, as part of the first-ever attempt to set nationwide standards for K-12 education. The Common Core State Standards not only could revamp what students do day-to-day in classes, but also offer the public a way to make meaningful, apples-to-apples comparisons of schooling across the nation.

For centuries, U.S. public education has been managed locally, often rooted in ancient ways: a teacher talks, students listen and read, their success measured by proving how much they’ve absorbed.

But concern about dismal U.S. student achievement, even among those labeled “proficient” on some tests, prompted states in 2008 to launch an initiative to modernize and share standards. Now 45 states and the District of Columbia will share K-12 goals set in the Common Core, which challenges teachers to offer more relevant, practical and rigorous lessons, and students to solve problems and think critically.

New standardized tests will debut in spring, so schools are training teachers, educating parents and purchasing materials and technology for the computer-only tests.

Fueled by $1.25 billion from the state for the transition, a cadre of consultants and innovator teachers is showing colleagues how to rethink lessons and methods.

“This is an exciting time for California,” said Deborah Sigman, deputy state superintendent of schools.

The standards cover only English and math, but spread responsibility for literacy to teachers of other subjects. Schools are free to decide what and how to teach, but their success will be measured on tests common to many states.

But in California, parents won’t know how schools do, because for at least the first, and perhaps later, years, the state will not publish results of the successor to STAR exams, known as Smarter Balanced tests.

The state has left the transition to Common Core up to school districts, and implementation varies widely. A few schools have shifted to new curriculum, some have converted certain classes or grades, but in many places teachers are still just learning what they should be doing differently. Among the “early adopters,” many embrace the change.

“For the first time, I feel that my students are truly understanding the algebra concepts in depth,” said Laura Fujikawa, of Bret Harte Middle School, in her ninth year of teaching math, and her first year teaching Common Core in San Jose Unified.

Before, students had to master lots of individual skills, but not necessarily connect them. Now they focus on fewer skills, relate them to each other and use them to solve real-life problems, Fujikawa said. For example, earlier this fall she asked her students to write an equation using a graph for a cellphone plan with 60 free minutes a month for someone talking 2-1/2 minutes a day. (The answer: y = -2.5x + 60.)

While some teachers don’t yet grasp Common Core’s changes, most welcome California’s decision to jettison its exhaustive list of grade-by-grade standards. Those made teachers beholden to the California Standards Test (CST), the core of the STAR test.

“We’ve been living in the world of CSTs for so long, we’ve gotten used to having lousy tests,” said Andrea Gould, math coordinator for the San Mateo Union High School District. “Common Core offers a lot of opportunities for more rigor in our classrooms, and also actually tries to get students to learn ideas more deeply and understand concepts.”

A years-long project led by the National Governors Association and the Council of Chief State School Officers, the new standards are based on research on how students learn best and what’s needed to prepare them for college and work.

“It’s not top-down any more,” said Randy Hollenkamp, site director at Bulldog Tech middle school in San Jose’s Evergreen School District. “It’s student-centered.”

Without a doubt, “it’s a mind-shift for teachers,” said Bulldog English teacher Suzanne Zamora.

What that means for students is, “We’re going away from feeding them as much information as possible,” she said, “to really making sure they understand.”

In English, students will read more complex texts, half of them nonfiction. They also will focus more on writing and academic vocabulary. They’ll read about science, technology and social studies, not just literature, and will move away from textbooks to draw on original material.

Recently, Bulldog eighth-graders were writing letters they imagined might have been written by an American Revolution-era historical figure. Prabjot Saini was writing as England’s King George III, telling his wife Queen Charlotte how he would militarily defeat those pesky colonists; to do her assignment, Prabjot was busy reading about the Battle of Bunker Hill.

Given more time to work on projects and work in groups, “I think I work a lot more efficiently,” said Hailey Luescher, an eighth-grader who was writing about Revolutionary General Joseph Warren, who fought and died as a private soldier.

Bulldog teacher Kelley Gosalvez, who assigned the letters, said, “Now kids are much more engaged in what they are doing.” And, she said, “what they are doing is much more applicable.” While students are studying history, they’re also learning writing.

That won’t happen in every class, as schools vary widely in training and direction, and generally teachers have wide latitude in running their classes.

While California has largely escaped the Common Core backlash engulfing other states — where conservatives have railed against a national curriculum and rallied to revert to previous content standards — not everyone is happy with the new regimen.

With responsibility for teaching literacy now spread across disciplines, some teachers have reservations.

“I didn’t go to school as a science major to teach kids how to write,” said Christine Smith, who teaches seventh-grade biology at Cabrillo Middle School in Santa Clara. She worries about sacrificing hands-on work and mastery of science concepts for reading articles and writing responses to them.

Science teachers also face the double-whammy of revamping their lessons according to new science standards, which California adopted this year. So far, she said science teachers haven’t gotten much direction from Santa Clara Unified.

Maureen Burt, who teaches history at Mount Pleasant High in San Jose, said she agrees with the Common Core goal of having students figure out problems, understand how other people think, and be able to explain their own reasoning — skills sorely lacking in recent years.

And yet, even while applauding changes, teachers draw on a reservoir of doubt.

Experienced teachers, Burt said, “fear a total pendulum swing where students are taught to think but lack knowledge to think effectively.”

In English, the Common Core stresses what’s already happening in good classrooms, said Joseph Hill, who teaches English at Carlmont High in Belmont: speaking and listening, participating in a civil discussion, knowing how to respond to others’ ideas.

If done right in a classroom, he said, “it’s a joy.”

Contact Sharon Noguchi at 408-271-3775. Follow her at Twitter.com/NoguchiOnK12.