A Very Long Time

It's been a very long time since I last posted on my blog. I went to check out technocratti today and I saw that I still have a large number of subscribers, so I was really excited and figured that I could write something. Recently, I've been spending significant time thinking about the best ways to motivate students to engage in discusion. As teachers how can we motivate students to converse with their classmates at high quality levels. I think the most important thing to drive this type of a conversation is the ability to ask the right question. The best questioners know that they should ask open ended questions and then allow students to think for a few minutes before answering. But, what I'm wondering is what are the different types of open ended questions? Meaning, I'm sure that not all questions that are open ended share equal quality. But how do you distinguish better open ended questions from weaker questions? I'm wondering if there is such thing as a paradigm for the quality of open ended questions? I'm looking for more than Bloom's taxonomy. What do you think?