For several semesters now, I’ve used Slack for my graduate courses in digital history. (Here’s a good introduction to Slack for teaching.) Judging by what the students tell me and what they write on the student evaluations, nothing I’ve done as a teacher has been as universally popular. Students appreciate a way to get detailed help from me quickly. Students seem to be less reluctant to ask questions when they can see that other people are asking questions, and when the answer is public for everyone’s benefit. And I can tell from the reports Slack sends that they use Slack to talk to one another.
I like Slack because it encourages an ongoing connection between the students and me during the week. Rather than only hearing from students once or twice a week when the class meets, I have a more or less continuous connection to them, at least to the extent that they choose. Slack has cut student e-mails in those courses to virtually nil. It’s very helpful for me to have a single place to go to communicate with students, and where I can easily turn a query directed only at me into a general lesson for the entire group. For technical questions, it is far easier to give explanations with code blocks and screenshots. It’s also really nice to see students help one another figure out difficult assignments.