I would like to be able to move modules into another module. For example, Unit 1 exam covers chapters 1-3, and each chapter is a module. Following the exam, I would like to "tidy up" the page, by pushing all exam 1 modules into that module. I was able to do that with folders in Blackboard.
Canvas does not support sub-modules.
Alternatively, instead of create 3 separate modules, you could combine the chapter modules into a single module using a combination of Text Headers and indentation.
I'm afraid that's the closest you'll be able to come to a sub-module configuration within Canvas.
If you'd like to see this added, you can submit it as an idea. To learn about idea submitting and the subsequent voting process, check out: How do I create a new feature idea?
It is an imperfect solution, but you can indent the "sub modules" to make them look like they are under the main module for each section.
The ability to include collapsible lists in Canvas modules has been requested before., or at least similar ideas. I think it's a great idea, allowing for cleaner content display in a manner the matches the outline of a course.
We use this approach at one of our institutions. Our course development process is comprised of essentially 7 modules and 14 units - 2 units nested within each module. A module in the course corresponds to a Canvas module, and then we separate the units by using Canvas text headers. Here is what that might look like in the course:
Actually, that is just dummy content from my sandbox, but I can just show you one of our actual past courses:
It is pretty straightforward and the students are really not confused. On the modules page they have the relevant assignment dates and point values, and I also point them to the canvas syllabus page and the calendar. The calendar agenda view is a great resource for them to see the due dates sequentially.