The runaway success of Khan Academy, which launched in 2008, showed the potential of online learning to revolutionize K-12 education. It meant that a great classroom lecture could be experienced by anyone, anywhere. The same year, the legendary business consultant and academic Clayton Christensen—who passed away last week at the age of 67—co-authored Disrupting Class: How Disruptive Innovation Will Change the Way the World Learns, applying his most famous theory to K-12 education.

When used "disruptively," software could solve the problem of students learning at different speeds. Christensen and his co-authors wanted to "flip" the structure of the classroom to make it student-centric. Students would watch online courses given by the world's best instructors. Educational apps would gamify learning, help track progress, and personalize content. Teachers could then use classroom time to help students tackle bigger, more conceptual problems.

Christensen and his co-authors predicted that by 2018, about half of high school classes would be delivered online. And they dismissed the objection that government bureaucracies and teachers unions would stand in the way of rapid change. But 12 years later, classrooms mostly look like they always have.

What went wrong?

"I would say the big lesson that I've had, is not that I'm disappointed, but just that it takes a long time to do this because you're trying to overthrow literally a century of policy and practice around our current school system," says Michael Horn, one of Christensen's co-authors and a Harvard MBA who specializes in education technology. "And all of a sudden we come along and say, 'wait a second, we're not doing it the right way.'"

Emily Raskin, a high school math teacher in Washington, D.C., says that the idea of a flipped classroom ignores the realities of student behavior.

"I think we look at the next big thing that seems great to adults, and assume that it's going to be the same thing for kids," she says. "So if you assign [students] to watch a video…if they are not really interested, they just kind of zone out, and they come to school the next day really believing that they have watched the video."

Were Christensen and Horn guilty, as the saying goes, of mistaking "a clear view of the future for a short distance," or were they fundamentally wrong? The current classroom model may survive for a long time to come—at least until software gets better at approximating student-teacher interactions.

And when change does come, chances are it will look nothing like what we had imagined.

Written, shot, and produced by Olivier Ballou; narrated by Nick Gillespie.

Reason is celebrating National School Choice Week. This story is part of a series that will be published over the course of the week highlighting different K-12 education options available to children and families.