I am half way through my intensive, 6 weeks long, SPAN 101 fully online course. Two very preliminary conclusions.
a) Because I didn't have pedagogical support at all, I read a lot of articles about online language teaching on my own. One of the things that is repeated over and over is the importance of community building, and to design activities to be done in groups. I carefully followed the advice. Well, I am sure it works for a semester long course. But in a 6 weeks course, it is a mess. I started receiving emails from students complaining they couldn't reach their group partners almost immediately (and those were the ones that actually bothered to complete the activity). Sometimes, it was the members of the same group, saying they couldn't reach each other. Six weeks go fast, so I would be very careful asking for activities the students can't complete on their own, because it is hard to come up with alternatives.
b) Organization is essential. I just spent hours trying to find where students uploaded a recorded assignments. Although the instructions were very clear as to where they should do it, half the class managed to upload it in the wrong place. Make everything as obvious as possible, and repeat yourself over and over if necessary. Chances are, somebody will need the triple message