Understood. My question was: Is notification via email the default or do they, as very new users, need to adjust their settings to opt-in to email notifications? Thanks!
It looks like the answer is Yes, by default, the Observer will receive an email duplicate of the course Announcement.
Here's what I discovered when I created a new Observer account and linked it to a student.
If an instructor is posting an announcement for only one section of a course (with multiple sections) do the observers see all announcements or only the ones posted for the section their student is enrolled in? Thanks!