answer:When I had to sign up for a live (on the computer) presentation time in an online class, the instructor started a discussion about it, that way we could see which spots were already taken and which were still available. As we replied to the discussion, the instructor filled in the time slots on the original post so people would be able to see their response was noticed by the instructor. In the initial discussion, the instructor gave us a deadline to pick our time slots and said that anyone that had not picked a time by that deadline would be assigned to the remaining times and it would be their responsibility to make it for the presentation.