The world population passed seven billion last year, and is projected to clear nine billion by 2050. On a panel Sunday on “Taking Education Digital” moderator Chris Dede, a professor of education at Harvard, began with a simple challenge: how will we educate all of them?

“We know that we are facing enormous capacity challenges worldwide,” said Dede, in reference to that challenge. And financial constraints will dictate that the world will not meet its educational needs solely by building “bricks and mortar” capacity, like traditional schools. The role for digital technologies in education is all but guaranteed. But how it will work is still an open question.

Steve Carson, External Relations Director at MIT’s OpenCourseWare initiative, began his remarks by breaking up education into three aspects: content, “learning activities” by which students work to absorb the content, and assessment. In other words, information, exercises, and tests.

To that Chris Sprague, CEO of OpenStudy, a startup that allows anyone to form study groups and ask each other questions in real time online, added a fourth dimension: people.

All four of these pieces are ripe for disruption, and some of them are already being transformed. MIT’s OpenCourseWare publishes all of MIT’s syllabi and course materials online for anyone to view. Envisioned originally as a means for faculty to compare notes, the site has served 125 million people. Delivering content cheaply is something the internet does very well.

Similar experiments into open education have followed MIT’s lead, with 17,000 courses available through the OpenCourseWare Consortium. When Stanford offered a course on databases online, 6500 users completed it, according to Sprague. The professor who taught it estimated that that was more than she had previously taught in the entirety of her career.

But the future of digital education needs to be more than putting “old wine in new bottles,” according to Dede. He is optimistic about the potential for mobile learning, and even “augmented reality” (which will be made possible by devices like Google’s forthcoming smartphone glasses).

To add to the challenge of building educational capacity, Dede reiterated that everything we know about human learning suggests that we all learn differently. So digital education can’t follow a cookie-cutter model; it has to allow for repackaging and remixing to fit the diverse needs of users.

That’s where Carson is optimistic. With content, learning activites, and assessment no longer all done by the same institution, savvy users “can mix and match those pieces,” he said. He believes that will lead to a “Tivo moment” for education.

“Certification is going to be the toughest nut to crack,” he added.

All of the panelists agreed that the last year had seen a massive acceleration in the pace of educational innovation, as well as outside interest by investors, government, and foundations.

Dede noted that he had lived through the rise of computers, which have already dramatically transformed education, but added, “I’ve never seen a time like the present.”