Just look at this interesting article, appears in the Australasian Journal of Educational Technology (AJET) 2007, 23(4), 455-469.
Comparing face to face, tutor led discussion and online discussion in the classroom
By Connie S. L. Ng and Wing Sum Cheung
This study explores the relative effectiveness of in class online discussion and face to face, tutor led discussion in preservice teachers' recall of concepts. Two groups of preservice teachers, who engaged in different discussion modes, were tested two weeks later on how many concepts they could recall. No significant difference in the recall score was found between the two groups, but the group involved with the in-class discussions using a threaded discussion tool achieved a slightly higher mean score in the recall of multimedia design concepts.
The online group completed a survey questionnaire on their perception of their use of online discussion. The majority perceived that they learned more online. The preservice teachers also indicated the mode of discussions that they preferred and the reasons for their choice. Half preferred to participate in in-class online discussions, rather than face to face, tutor led discussion, during class time. The findings suggested that educators and learners may choose either in-class online discussion or face to face, tutor led discussion without fear of significant disadvantages to learning.