Flash: should be good to make an online software tutorial. Not sure how to set it up, but it’s worth a try.
…later it’s taken a while, but I have a workable slide show ready, which just needs captions adding. the image quality seems poor as Flash converts bitmaps to jpegs, set with enough compressoin makes for obvious Jpeg artifacts.
Below is a scan of a demonstration picture I did in-class for a year 10 lesson. I decided to keep this one because often they are rather rough and incomplete. It was finished off after the grou phad gone.