A group of U.S. education technology startups, in partnership with dozens of top U.S. universities, now offers MOOCs on everything from poetry to physics. Course platforms feature lecture videos, other multimedia content, embedded quizzes, discussion boards, and online study groups. Essays and other projects less suited to automated grading are reviewed by classmates based on rubrics. Interaction with professors and teaching assistants is rare. Completing a course earns you a certificate, and several U.S. schools have begun to accept MOOCs for credit.

The startups' founders say their goals are at once practical and humanistic -- an effort to overcome rising education costs and a shortage of resources and make top-quality learning accessible to the masses.

Anant Agarwal, an MIT professor, is the president of edX, a nonprofit collaboration between his university and Harvard University that currently offers more than 60 MOOCs.

He believes his and similar projects are nothing short of transformative.

"I think education is not going to be the same ever again," Agarwal says. "I really describe this technology and MOOCs as the biggest revolution in education since the printing press -- and that happened 500 years ago."

Other, more impartial observers have high hopes for MOOCS, too. But given their novelty, some assessments are more cautious. Critics point to the courses' high dropout rates, the lack of face-to-face interaction, and the risk that the for-profit companies offering MOOCs may one day begin charging students if they fail to secure other revenue sources.

One company, Coursera, has attracted over $20 million in venture capital. It currently makes much of its money by licensing course content to universities. It also gives students the option to pay for perks including electronically verified course certificates and electronic course records to send to employers or schools.

One thing that no one doubts is that MOOCs are gaining in popularity -- and fast. Agarwal says that after just a year, edX is approaching 1 million learners from 192 countries. In the same time span, Coursera has attracted more than 3 million students. Agarwal boldly predicts that over the next decade or so his initiative will attract 1 billion international learners.

But he concedes that subjects such as politics, history, and philosophy, provided by generally liberal, Western institutions, could cause problems if MOOCs gain such reach.

"I expect that challenges will continue as what might be considered gainful education in one part of the world might be considered disruptive in a different part of the world," Agarwal says. "We haven't had examples of nations or others blocking edX content itself, but some of the infrastructure over which our content is distributed are not accessible all over the world. YouTube was blocked in some nations, for example in Pakistan and China, and we distribute video over YouTube. So there, what we did was we made the video available for download on our site so students could have an alternate way [to watch]."