The unique characteristic of blended learning is that a significant portion of the activities occur in two areas: in person and online. Various other pedagogies - lecture, problem-based learning, Just-in-Time Teaching, cooperative learning, and others - can then be superimposed on the blended framework. The challenge of blended learning is to link, or blend, what happens in each medium so that face-to-face and online activities reinforce each other to create a single, unified, course. A large body of literature, often categorized as the no significant difference literature, is often cited in support of the contention that there is no discernible benefit in the learning outcomes of students taught online compared to students taught in a face-to-face environment. In fact, careful meta-analyses of this literature reveal an important difference: Online learning, and in particular blended learning, can result in significantly better student learning compared to learning in the conventional classroom.
http://cgi.stanford.edu/~dept-ctl/cgi-bin/tomprof/posting.php?ID=1171
