Getting students to be responsible for their own learning objectives can be a challenge, especially in an accelerated term such as ours. On discussion boards, this can be particularly challenging.
To facilitate that goal, I ask bolded open ended questions on the board, but not to every student, because I try to mix up my response types to keep their interest. That said, many times students don't circle back around to answering the questions. I could be more diligent about following up with them one on one when they fail to do this. The expectation is set from Day One, however, that this is part of the etiquette of discussion boards. After all, you wouldn't just ignore me face to face if I asked you a direct question, would you? Probably not.