Using student's questions as a measure of learning quality

I recently attended a conference, where I was lucky enough to hear both Hywel Roberts and Guy Claxton independently deliver thought provoking presentations on the challenges of creating effective learners who take responsibility for their learning. I can't recall which of the speakers made the suggestion, but an interesting idea was highlighted. The idea was to ask a peer - I'm thinking this could even be a rotating student role (I'll let you know when I've tried it!) - to record the questions asked by the students throughout the course of the lesson. Students who are learning and are an active part of this process - indeed the central part - should have questions born of an eagerness to learn more. The focus currently in lesson observations tends to be on teacher questions - "why" versus "what", for example, in the pursuit of deep thinking. Students who have questions, and who are able to share them, are taking control of their learning and engaging in discussion with their teacher rather than simply sipping at the spoon being predictably waved in front of them. A lesson with no questions is probably too safe, too teacher-led and is likely to be hindering students development as truly self motivated, independent learners. The list of questions can then be used as a tool for evaluation and review. The peer observer, therefore, simply records the questions and does not offer judgement or criticism.