Does the Canvas box includes Announcements?
According to the Canvas Guides, no, announcements are not included.
That picture looks like it came from How do I view analytics for a student in a course? If you read the second paragraph just below that picture, it says (I added the bold):
To view the details of the bar graph, hover over the specific bar you want to view. You can view the date of the communication and how many messages were sent. A message is an individual message passed from one user to the other; in message threads, each message is individually counted. In group conversations, interactions are counted as long as the student is one of the recipients. Notifications are not included in analytics unless the user acts on the notification and generates a new message that passes through the Canvas Inbox. Announcements are not included in communication analytics.
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