Post-secondary institutions and their students tend to be ahead of K-12 schools in their adoption of online and blended learning, so it’s useful to keep an eye on the college digital learning landscape for clues about the directions that K-12 digital learning may take. Fortunately, the federal government tracks post-secondary distance learning (the large majority of which is online) with data tables and a summary report, and e-Literate reports on and interprets the latest government numbers (which are from fall 2016) here and here. In addition the Babson Survey Research Group, which used to conduct its own survey, reports on the numbers as well. Babson provides a useful summary:

“Distance education enrollments increased for the fourteenth straight year.
The number of distance education students grew by 5.6% from Fall 2015 to Fall 2016... representing 31.6% of all students.
Total distance enrollments are composed of 14.9% of students taking exclusively distance courses, and 16.7% who are taking a combination of distance and non-distance courses.
Distance education enrollments are highly concentrated in a relatively small number of institutions. Almost half of distance education students are concentrated in just five percent of institutions…
The number of students who are not taking any distance courses declined” by 11.2% between 2012 to 2016.

e-Literate adds a nice graph showing these numbers:

How do these numbers compare to K-12?

First and most important, we don’t really know because the federal government and the large majority of states are not collecting similar data for K-12 schools. It’s notable that private sector estimates of post-secondary online enrollments, from before the start of the government survey, generally overestimated the number of students taking online courses.
Even though we don’t have good current numbers for K-12 students, based on extrapolations from Keeping Pace research from a couple of years ago, the percentage of college students taking distance courses exclusively is at least 10x higher than the number of K-12 students doing so, and probably more like 15 times higher.
The percentage of students mixing online and onsite courses in college is also higher than the K-12 equivalent, but the difference is far smaller. Based on very rough Keeping Pace estimates, we guess that the percentage of college students mixing online and face-to-face courses may be about twice as high as the K-12 percentage. In addition, when we consider high school students only, and include credit recovery courses in the mix, the percentage of high school students mixing online and f2f may be higher than the percentage of college students doing so.

The latest on post-secondary online learning