Snapchat: use this for annotation
Discord: use this to coordinate projects/facilitate asynchronous communication between students, compartmentalize project groups
Twitter: use this to write lesson plans
Snapchat is great because it not only default the ephermarality of generated content, but gives users the extra steps to save and preserve the content. It creates a culture of documenting the fleeting human experience, while offering the affordances to reflect on and preserve the right ones. It puts ownership in the responsibility of downloading your snaps, or "saving to camera roll". Other social media is kind of like a clusterfuck of experiences that have no risk or consequence upon the initial upload aside from saying something racist or something. Other than ephemerality, it has THE BEST features for annotations. Any learning material can be "snapped" as a picture, and snapchat makes this documented experience a canvas, where you can draw or add text onto the artifact. There is also a sticker function for cutting out pieces of a media (picture or selected passage) and pasting it onto other images. The superimposing of pictures onto relevant text can be used for making connections. The ownership of the user/learner is conveyed through not only the act of preserving the moment, but also the remixing and editing of it to create meta information. There are a lot of instructional tools that do the same things snapchat does with recorded lectures but that just grounds the student action in schooling, or an extrinsic obligation rather than the whim of using an informal tool to capture and participate in the learning material.
Discord is an asynchronous chat as well as voice chat software for gamers. It is the closest thing to the IRC chat rooms today. Discord is split into a servers that are created by the user and that can be joined via invitation. Each discord server can have sets of channels for the compartmentalization of subtopics according to the server's theme. An application of this could be a project management course server, where each group project has a channel within that server they can join to chat with their team in. It's also important to have introductory and discussion channels that way personal interests and similar trains of thought can be revealed prior to assigning groups. Another application can have a channel for each topic or module taught in the course so conversations be more dynamic and organic. The creator of the server can regulate access each user has to what channel, and can even implement bots for further user actions.
Twitter can be used for discussion based assignments too, but I'm way more interested in the 280 character limit. I'm the biggest sucker for verbose and overly complicated lesson plans, so twitter helps me identify what is the most important information needs to be conveyed in writing a prompt or question. If it exceeds the character limit, it shows me whatever I activity I planned was too complicated or had too many parts. I guess this same idea of writing whatever is the most necessary can be applied to discussion assignments too, as from my experience, students would write 500-700 word discussion posts, only to summarize whatever they read rather than reflect/respond to it authentically. Even the replies are stale, often sounding like "hi x, great response! i like that you said x and y". I think this is attributed to some sort of anxiety or overcompensation of making your response gradeable. The event of exceeding your character limit shows that you'll burn yourself out if you try to write a monolith of a response only to say a lot of nothing. The attitude of responding in short bursts encourages the iteration of ideas as well as the immediacy to want to respond to others. Twitter facilitates natural dialogue in putting an emphasize of your thoughts through constraint.