Marbach-Ad and Sokolove probe the issue of improving students' reading questions deeply in their 2000 paper (cited below). Their most successful method involves several parts: Ask students regularly for their "best question" after a reading. Give students a clearly defined rubric with real examples for what good questions are. Make many opportunities for students to practice asking questions, evaluating questions, and answering questions. Give student questions pride of place in the classroom, including using wireless mics so that other students can hear students asking the question.
The paper is somewhat interesting but not especially strong from an experimental standpoint. (Of the four techniques I mention above, they provide some quantitative evidence for the combined value of the last two.) However, the ideas may be worth trying out in our own classrooms.
I've appended their rubric for questions below. It's not directly adoptable for CS, but it's an interesting starting point.
Their most interesting mechanism for student practice with questions is to have stable student teams submit their questions as a stack. Before submitting, the students have a few minutes to decide which questions are the best and put those on top. This seems like a simple way to enforce student practice discussing and assessing questions.
Unfortunately, the paper does not address what to do with the questions the instructor received. In CPSC 111, we chose 10 questions at random to answer every week and sometimes answered additional questions that were common or interesting but didn't show up on the random list. This was somewhat satisfying to students. A complementary currency system (where students can purchase answers or invest in questions?) or a voting system (like ActiveClass's) might be more successful.
Marbach-Ad, Gili and Sokolove, Philip (2000). Can Undergraduate Biology Students Learn to Ask Higher Level Questions? Journal of Research in Science Teaching 37(8): 854-870.
Marbach-Ad and Sokolove's taxonomy for student questions in Intro Biology (developed from sample student questions):
Category 0: Questions that do not make logical or grammatical sense, or are based on a basic misunderstanding or misconception, or do not fit in any other category. (This is a "catch all" category that instructors can readily subdivide for teaching purposes--for example, when grading written questions. In this case we chose not to subdivide the category in order to focus on the characteristics of desirable questions.)
Category 1a: Questions about a simple definition, concept, or fact that could be looked up in the textbook (i.e., "what is meant by the polarity of the membrane?").
Category 1b: Questions about a more complex definition, concept, or fact explained fully in the textbook (i.e., "what does it mean when it is says air moves through a bird's lungs?").
Category 2: Ethical, moral, philosophical, or sociopolitical questions (i.e., "carbon monoxide is a very deadly gas binding to hemoglobin much faster than oxygen. If it is so deadly, why are there no carbon monoxide detectors throughout the dorm halls?").
Category 3: Questions for which the answer is a functional or evolutionary explanation. (In this case students begin by asking a question that relates to function and could, in principle, be answered in functional terms--"Why do people have an appendix?"--however, the deeper answer is more often related to evolution than to function (the human appendix is a vestigial organ)).
Category 4: Questions in which the student seeks more information than is available in the textbook (i.e., "what causes the 'rumbling' in your stomach when you are hungry?").
Category 5: Questions resulting from extended thought and synthesis of prior knowledge and information, often preceded by a summary, a paradox, or something puzzling. (i.e., "In chapter 35 it says that caffeine, if taken excessively, can disrupt motor coordination and mental coherence which can cause depression. I known that Coca-Cola has some amount of caffeine in it. Does this mean that excessive consumption of it could lead to depression . . . ?")
Category 6: Questions that contain within them the kernel of a research hypothesis (i.e., "I have heard that some people snore so badly that they stop breathing during their sleep. What correlation is there, if any, between 'heavy snorers' and a higher instance of apnea during REM sleep. Can the attention their nervous system is devoting to a dream, interfere the regulation of respiration?").