Google Slides does not really have a chat feature, but the program does allow you to comment on a student's slide, and the student can send a comment back to you. This is a great opportunity to give positive feedback to the students as well as offer suggestions for improvement. The students loved it when I sent them a message and were eager to reply back to me.
The students would tell me when they sent me a message back. Usually it would be a thank you or an ok like the picture above. I would read these messages and move on without an reply; however, my students were disappointed when there was not a reply to their simple message. Therefore, if Google is reading my post, I think it would be a good idea to add a like feature to the comment box so that a student's comment can be acknowledged easily. This would make many of my students very happy. Until then, it is best to acknowledge all of the students' messages with a simple reply or they will continue pestering you until you do.
I also liked to drop a few inside jokes in the comments for the students to enjoy (even though the students often didn't get my humor). One of the students always used speech call-outs in her projects. I was very surprised that she didn't use one in her project about the groundhog. I nicely made the suggestion, and she revised her work.
Commenting with students works best with Google Slides. Everyone is working on the same presentation, and it is easy to move back and forth between all of the students. The commenting feature also works in Google Drawings, but it is hard to maintain because you have to open up each student's project individually. I probably had a least 15 tabs opened at once, and my computer froze.
My next step in using the comment feature in Google Slides is to have students look at a completed presentation and give each other positive feedback through comments. I think the students will enjoy chatting with each other, but I will have to closely monitor the conversations to make sure that they are treating each other with respect. I will update you on how the it goes after I have the opportunity to test it out.