The US Department of Education published a report this summer that compared online versus traditional in class teaching from 1996 to 2008. The study concludes that “On average, students in online learning conditions performed better than those receiving face-to-face instruction.”
The report analyzed 99 samples across the 12-year span, most of which take place in college and continuing education settings, with only seven being K-12. Extracting the K 12 studies still shows that students in online learning settings perform better than in traditional classrooms. However, the difference is slim and statistically not significant, requiring caution to generalize these findings.
The report further concludes that hybrid forms, the combination of online and face-to-face instructions, are the most effective. Interesting to note is also that the observed learning advantage through online settings doesn’t come through the medium per se, but through the different use of time (students tend to spend more time online with the material than in the classroom), curriculum and pedagogy. Online learning is much more conducive to the expansion of learning time, a personal treatment of the material and the opportunity for new forms of collaboration.
Taking into account the ambiguity of the study’s findings for the K 12 setting in contrast with the recent rise of new forms of web resources, web based applications as well as collaboration technologies and the pace of change in online education, the question of efficiency looses its relevance. This presents an opportunity to integrate online learning into classrooms and experiment with these forms of pedagogy.

{ 2 comments… read them below or add one }
I don’t know the details of these studies, but I wonder if those learning online are a biased sample of people with greater motivation and work ethic than those who simply sit in classrooms because they are forced to.
I would agree that the sample is likely biased. I also think that following your “nose” is a compelling way to learn and one that has proven over and over to produce great results. A major selling point of the online environment is the freedom it represents. Creating a semi-limited environment where there is a degree of autonomy balanced by a rich resource of dialog and engagement opportunities are what we hope will be most effective.