For the past four years I have been attempting to develop a fully on-line earth science sequence for  non-science majors.  In our system we call it the general science sequence.  At the end of this year I will be "retiring" from teaching distance courses and making the recommendation that we stay with a hybrid sequence (on-campus lab) rather than attempt to go fully on-line.  As a point of closure I would be most interested in hearing from some of you that have been involved in similar efforts.  In particular I would appreciate hearing about how you have dealt with the following issues or if you know of research dealing with these issues.

• Encouraging inquiry and problem solving in on-line environments - My experience has been that the on-line experience is a highly scripted one that doesn't lend itself easily to the kinds of flexibility and open-endedness that is a hallmark of inquiry-based instruction.  This scriptedness also makes teaching earth science on-line somewhat problematic, since the earth sciences are a bit "messier" than math, physics, chemistry, or accounting.
• Providing the kind of near instantaneous, social trouble shooting that is part of an on-campus course -  The asynchronous aspect tends to slow down many activities quite significantly.  We have tried video-conferencing options such as Elluminate, but this adds a level of technical complication for students who are still struggling with basic technical tasks such as sending an attachment to an email.
• Coping with student expectations about distance courses -  I sense there is a certain amount of scuttlebutt amongst students (and maybe even advise from college counselors) that if you are looking for an easy way to fill a requirement take an on-line course.  Students seem to arrive in our courses with the illusion that they will be spending far less time completing an on-line course than they will its on-campus equivalent.  They also seem to arrive with the impression that the experience will be a canned, "work-at-your own pace" experience.
• Coping with student frustrations - For much of the past four years, we've spent a considerable amount of time trying to figure out how to deal with the many frustrations students have expressed on-line.  While many of these frustrations are rooted in the all-to-common technical difficulties that come with teaching on-line, my own hypothesis is that many more of these frustrations stem from students finding on-line science different from their expectations, trying to work alone without the support of instructors and other students, and their own discomfort with science (e.g. "Science isn't my thing").  Add to this the anonymity of email communication and you often get students expressing themselves in ways that they would not do in a face-to-face encounter.