The way I use it is creating a channel for each class – when I’m teaching the same one a second time I delete the old Slack channel and create a new one with same name / number to clear out my former students.
How we use it is different for each class. The channel that’s still active is one from a class I taught on food in literature and culture. One of the assignments for the course was to post at least two food selfies a week. Once they got into it they were commenting on each other’s pictures, which was the outcome I hoped for. In more straight up literature or film course, I have them either live tweet their watching of the film or put up at least 3 comments or replies to someone else’s comments about the reading.
I used to teach using Twitter quite a bit, but it’s become such a fraught environment, especially for students of color that I think of the Slack channels as public / private spaces.
I don’t get notifications every time someone posts – I have mine set to only notify me when someone @s me or sends me a private message. I let them know in advance that I only check Slack a few times a day, but encourage them to ask their questions in the open channel and then give a few extra credit points to students who answer other students correctly before I can.
Our LMS is Blackboard and it’s terrible. The students hate how clunky the forums are and don’t engage with each other very much using them. As one of my students commented, the philosophy Bb uses seems to be “why use click when you can do eight?” Using Slack seems to energize them and they get into communicating with each other rather than just with me. I think they especially like how good Slack is, as opposed to Bb, on their devices. They like to do things on their phones .
Edit to add: Bonni Stachowiak (think she’s been a guest on MPU) with the Teaching in Higher Ed podcast has had a few discussions on using Twitter and Slack in teaching. It’s a great weekly podcast (and I’d think so even if I hadn’t been a guest!)