Discussions

Yes.  To ensure students cannot first view their peers' posts before creating their own, within the discussions tool for that topic, make sure to set up your discussion as a must-post-first forum (i.e. "Users must start a thread before they can read and reply to other threads").  Some faculty prefer this setting so that students aren't swayed from the outset by the initial posts in the class.

While any discussion is open/unlocked, D2L Brightspace enables students to edit threads they have posted to improve their quality (e.g. grammar or content).  Unlike Canvas, instructors cannot disable a student's capacity to "edit thread."  That said, instructors can open any discussion thread, click the drop-down context menu for that topic, and choose "view post history" to view the revision history.  This function includes the ability to view deleted posts or restore them if needed.  

In this light, instructors who strongly feel that students should not be able to edit original posts will need to clearly state if students should not edit original threads, and explain their rationale.  If desired, you can also note your ability to view revision history for each thread.  That said, keep in mind that promoting non-editable posts, as a practice, may unreasonably penalize students who accidentally click submit before having a chance to review their writing or the discussion guidelines.