Roberts estimated that he spent 80 hours pulling together open-source materials for his textbook, working late into the night to write some sections himself when he could not find good material. Before the pilot, he said, he found no centralized place where faculty members could gather open-source materials and relied heavily on Google searches.

He was motivated, he said, by frustration over textbook editions that were "constantly updated with little justification" and by the desire to save students money.

Roberts said traditional textbooks provide some value, but added, "The question is: Is it worth the cost that students are paying for it? If we can get the job done without it, I think we have an obligation to our students to do that."

Bishop, who believes open-source textbooks will become more common, said the Maryland system could develop its own library of quality open-source materials. Still, she noted that quality control remains an issue.

"Anybody at this point can write a textbook and put it out there for consumption," she said. "It's still sort of a crapshoot, frankly, if the textbook you just downloaded is going to have the kind of quality that you want for your course."

Advocates for open-source textbooks complain that publishing companies drive up costs by "bundling" textbooks with CD-ROMs containing software that adds little value. Publishers also often release new editions of textbooks, making it difficult or impossible for students to resell their books after a course ends.

The textbook publishing industry is "not opposed" to open-source textbooks and is even partnering with some providers, said David Anderson, executive director of higher education at the Association of American Publishers. But he said traditional textbooks can cost up to a few million dollars to produce, and he is skeptical that such an effort can be re-created on a large scale for a product distributed for free.

Anderson said traditional textbooks are usually written by several academics and are peer-reviewed to ensure they are accurate, free of typos and well-sourced. "When you're looking at open-source textbooks, that may or may not be the case," he said.

Anderson said the industry has already developed cheaper alternatives to the hardcover, full-color textbook: three-ring-binder editions, black-and-white editions or options for students to buy individual chapters electronically. He pointed to CourseSmart, a company offering a $200 package deal that enables students to rent electronic versions of six textbooks.

Though the concern over textbook costs is a perennial one, efforts by state and university officials to reform the system have been largely unsuccessful. In 2005, state lawmakers directed the university system to evaluate a "textbook consortium" that would coordinate purchases with an eye toward reducing prices.

But the university system ultimately said the consortium would be unworkable. Among the reasons: Universities had an obligation to honor their contracts with bookstores, creating such a system was too expensive, and the measure could run afoul of federal anti-trust laws.

Student advocates for open-source textbooks point to a study released in January by the U.S. Public Interest Research Group, a nonprofit advocacy organization. About 65 percent of the 2,000 college students the group surveyed across the country said they opted not to buy a textbook because of the cost, and nearly all of those students were concerned it would affect their grade in the course.

Roberts said the Introduction to Psychology open-source textbook he created is now in use by about 700 students each semester. The students he's surveyed are generally pleased with the experience, he said, with the exception of a few who prefer to have a printed textbook to write in.

There are other benefits to open-source textbooks, he said. "Right now, if a study comes out, it can take a year to show up in a textbook. We can update it overnight."

In contrast to the work it takes for a professor to create an open-source textbook, textbook publishers can make a teacher's job easy, Roberts said. Professors who assign a textbook can get a package of PowerPoint slides and prewritten exams from a publisher, saving them time designing the course.

Roberts also said publishing company sales tactics can be aggressive. Salespeople will walk into a professor's office unannounced to pitch a textbook, he said, or cold-call them.

"They come and find you," he said.

Robert Javonillo, a Coppin State professor participating in the pilot program, said his Introduction to Biology students seemed "relieved" to learn that their assigned course materials would be free. The hardcover version of the textbook he assigned before costs $158. He said the open-source materials have been high-quality, with the exception of some of the illustrations, important for learning about biology.

"Maybe one of the bigger issues is in certain academic circles, the rigor of a course is judged by the textbook you use," he added. "If you stray from that, you might be met by some furrowed brows."

Javonillo said it's too early to tell whether the different materials have affected his students' learning.

"I'm optimistic about this lowering the cost of college attendance in the near future, but I'd be curious about what the publishing companies are going to do in response to this," he said.

"You can't beat free."