For a modern take on Shakespeare, Montgomery County middle school teacher Amy Soldavini recently borrowed an online lesson comparing hip-hop artists to the Bard. Math teachers at Thomas Jefferson High School for Science and Technology in Fairfax County sometimes assign students to watch free instructional Web videos at home so they can solve more challenging problems in class.

And Billy Shulman, a Prince George’s County high school government teacher, often adapts civics lessons from a repository on the University of Virginia Web site.

“I don’t really use my traditional textbooks,” Shulman said. “There’s almost too much good stuff online.”

Enterprising teachers have long scoured the Internet for ways to improve on their textbooks or local curricula. Now, though, lessons accessed via the Web are proliferating in the classroom as never before and are challenging the position of the powerful education-publishing industry in public schools.

Fueling the trend, most states in the past two years have embraced national standards for what students should learn in English and math classes. The new standards should make it easier to share curricula across state lines. In addition, budget pressures after the recession have led many schools to scale back or freeze purchases of textbooks and other teaching materials.

As classrooms become better equipped with interactive white boards and other gadgets, more teachers are looking for digital content and adopting an assumption that prevails in much of the World Wide Web: That content should be free.

“Now that expectation has entered the American classroom,” said Jay Diskey, executive director for the school division of the Association of American Publishers.

Seventy-four percent of elementary school teachers reported that they used free Internet resources for lessons that they flashed on computerized white boards or offered on desktops or other gadgets, compared with 65 percent who said their digital content came from commercial providers, according to a January survey by Simba Information, a market research company. The survey found that middle and high school teachers also gravitated more toward free online content.

Analysts say private vendors are likely to regain their edge as school budgets improve, but the market is undoubtedly changing.

Most school systems across the country have delayed new textbook purchases, which often run on a six- or seven-year rotation, to bridge budget gaps and to wait and see what the next generation of standardized tests will look like. New tests, tied to the national standards, are scheduled to begin as early as the 2014-15 school year.

Sales of textbooks and “core instructional materials” dropped from more than $4 billion in 2008 to about $3.3 billion in 2011, according to the Association of American Publishers. Pent-up demand for new materials could lead to a buying spree.

But advocates for open-source materials — free online content that can be shared and customized by users — say the national standards offer a unique opportunity to create high-quality curricula at low cost.

With Maryland, more than 40 other states and the District basing instruction on the same standards for the first time, they will not be forced to shop for separate textbooks. Instead they can pool resources, hire the most talented curricula writers and subject experts, and share the results. (Virginia is among four states that have not adopted the full standards.)

Foundations have kicked in millions of dollars to promote access to free instructional materials tied to the new standards. The federal government is also encouraging the movement.

U.S. Education Secretary Arne Duncan lauded the “tremendous transformational promise” of open resources. “In America, what a child gets a chance to learn will no longer depend on their ZIP code,” he said in an online video.

Federal Race to the Top funds are helping Maryland and the District develop curricula based on the new standards that can be used by school districts anywhere.

Some states have invested in online textbooks thatcan be easily updated and printed and offered to districts for free.

A free digital textbook initiative in California launched in 2009 led to the creation of nine open-source math and science books. In Utah, the state office of education is developing open-source textbooks in language arts, science and math that could be ready by the fall. Virginia also created an open-source physics “flexbook” in 2009; it’s written by volunteer teachers to help update lessons with more cutting-edge research.

Much of the growth in free online resources still comes from the grass roots — teachers sharing with teachers.

Arlington County math teacher Kevin Hall likes to post his most successful algebra lesson plans on, a Web site that boasts more than 250,000 members.

OER Commons, a California-based organization, maintains an archive of free educational resources and offers a new tool to measure how well aligned they are to national standards.

Commercial publishers offer expertise and reliability, things you can’t count on when sifting through thousands of hits online, said Diskey, from the publishers association.

“We question whether [free online textbooks or materials] are sustainable,” he said. “Most people don’t realize they are like a puppy; they require a lot of care.“

The publishers also offer complete packages of content, including print and digital textbooks, and a range of supporting quizzes, activities and materials, so teachers don’t have to work so hard to assemble lessons.

Major publishers, including Pearson and Houghton Mifflin Harcourt, are marketing new books and materials advertised to match the new standards, with more in the works. In one unusual effort, Pearson is partnering with Montgomery County to design an elementary curriculum and matching assessments that will be sold nationwide.

To adapt to the changing market, major publishers are moving beyond textbooks and into a broader world of educational technology and consulting.

At a particularly turbulent time in public education, with legions of reform-minded programs transforming classrooms, the companies are positioning themselves as experts who can walk school systems through the changes and help improve student achievement.

They offer training and software to help schools adapt to the new standards and teacher-evaluation systems.

The traditional printed textbook is dying, said Peter Cohen, chief executive of Pearson School, and that’s a fact that makes industry changes inevitable. “The only real question is when,” he said.