Hi jane,
Canvas provides us two ways to get a message out to an entire class at one time.
The first way to get a message out to your entire class is to use the conversations feature. (How do I send a message to a user in a course in the Inbox as a student? )
The second way is to post an announcement (https://community.canvaslms.com/docs/DOC-10405-415250731 )
Hope one of these two ways helps you get the message out to your class.
