How does a Twitter discussion compare to a BlackBoard Discussion? To an in-class discussion?

Twitter discussions are usually short in length, as users are limited to 140 characters of text. It is more of a direct method of communication. Twitter also shows only the latest tweets, so responding to tweets that were tweeted several days ago are no longer relevant. BlackBoard discussions is not limited to this, as anything can be discussed through BlackBoard whether they happened today or in the past. These discussions are limited, however, to how often responders submit responses and this can delay or be detrimental to the flow of conversation. In-class discussions remove these delays, and these conversations are usually the most involved and complex out of the three. The only disadvantage I can think of is the ability to communicate with others in short notice, as you would need to set up a discussion were everyone would need to be present right away. This is exactly where Twitter would come in handy, as users are mostly present at all times (by receiving notifications) and can be involved in a discussion very quickly.