What is the difference between sending an email to the entire class and sending it to each student individually?
The biggest difference is actually seen when a student replies. If you send a message to the entire class, and a student replies, that reply also goes to the entire class. If you send individual messages, a reply is private between you and the student.
Here are some guides that will also help:
How do I use Conversations as an instructor?
How do I send a message to all course users in Conversations as an instructor?
Thank you! Is there a way to adjust the actual content…make the type larger, bold, underlined?
The Conversations Inbox is more of a messaging action than a fully developed email client. So, no, there is not a way to format text.
Add rich-content editor to Conversations is currently on the Product Radar. Many Canvas Community members have also requested and/or see the value of having more formatting option in their inbox. Feel free to vote and to add comments to the discussion!
Retrieving data ...