There is a large list of Dialogs, but no indication as to which ones we have completed.

I suggest that once all the exercises have been completed in the Dialog and the user clicks DONE, put a check mark or other indicator in the list of Dialogs so we know which ones we have completed. You may also want to have an "in progress" indicator for Dialogs where some exercises have been completed, but not all. The "in progress" is less important, but the Completed indicator would help us to see what is outstanding from the large list of Dialogs, as well as give us motivation to see all that we have completed.