[mathking]

I am doing this in for my classes this year. (I did it some last year as an experiment, and this year I am trying to do a more detailed analysis of its effectiveness.) And have a colleague who has been doing it for a while. It works, sort of. Don't get me wrong, I like the idea and it has real advantages, but as an every day thing I don't think it works as well as some of its proponents believe.

Most of the problems have already been mentioned here. When kids don't watch the lessons in the evening, they aren't ready to do work in class. I have found that if I keep the videos to 10-12 minutes or less the kids will watch them. Sometimes this means breaking my 40 minute lecture into 2 or 3 pieces. I have also found that some subjects are just too complicated to be explained effectively in a video. For those I will try to lay the groundwork in a short video and then do the main lecture in class. This is particularly true for topics that really require discussion in order to be effectively learned. I have found that for math and CS classes "flipping the classroom" some of the time is effective and gives me more time to work with students while they are working, rather than just listening to me talk.

On a related note, one thing a lot of my colleagues (and I) are doing is recording (in some fashion or other) our lectures. Whether this is a digital recording or a PDF of all of the work done on the smart board, we save it each day and post it to our web pages. This gives students "back up" for their notes. They often remark that seeing the sample problems in class worked out again (often with rewind involved) at their own pace is helpful.