For announcements use "News Forum" ("Nachrichtenforum" – instructions: as video, as cheat sheet)
For student questions and answers use "Forum" (instructions: as video, as cheat sheet)
For surveys, to collect opinions, use "Feedback" (instructions: as video, as cheat sheet)
For short opinion polls use "Choice" ("Abstimmung" – instruction: as video)
For consultation hours, brainstorming sessions, short revision sessions use "Chat". Here are two tools available: the TUWEL Chat (instruction: as cheat sheet) or the TUchat (link)
A hint: Encourage your students to collect content themselves, according to the motto "Students help students"!
Via "Wiki" (instructions: as video, as cheat sheet)
or set up a separate "forum" for this purpose
Another tip: You or your assistants can moderate the forum by correcting wrong answers.