I use Tony's method. I actually backup the course as many times as parts that I want. I select just the Lessons I want for the new course when I do the backup and change the name of the backup to make it obvious which is which. This is easier than deleting courses from the same course restored for each of the parts. I have learned to leave the original in place for a bit (hide it) and not to use it as a new course. I think I would use Tony's method more often than not.
I tried the import feature and I had to do a lot of work on my images in the new course which I wouldn't have to do if I used a back up from the original course.
It's worth the work when you find that you have put way too much in one class.
Paula C
