I ask my students not just to answer the question posed, but also to explain why they think as they do. I have received generous feedback from them over the years, and have implemented many of the suggestions that they have offered. I have found this feedback invaluable in fine-tuning my teaching. I am, simply put, a better teacher because of the useful commentary and criticism I have received from my students.
The notion, put forth by one recent commentator, that my students lack the competence to judge my performance, is ludicrous. They are, if anything, more finely aware of multimedia communication, and more sophisticated at some of the modes of communication I use in my classes, than I am. I would not trust them to judge my overall value as a scholar and an intellectual, but I emphatically do trust them to be able to make discriminating judgments about performance. This is especially true of lectures before large numbers of students, which certainly have a strong performative element to them. Student evaluations are a diagnostic tool, and they have their weaknesses. They should not be the sole instrument on which I rely to improve my teaching. But the notion that they have no value at all is silly.
I see lots of my colleagues who get defensive about their student's criticisms. It stings to have some thoughtless 19 year old tell us they think we are lacking, especially given that most of us work quite hard at our jobs. But we should not take their criticisms at face value. They are well worth considering, it seems to me, if your agenda in reading them is to figure out what you are doing right, and what you might wish to improve. I do not think they provide the sole basis on which I work to improve my teaching, but without them, I would be unable to fine-tune my pedagogy anywhere near as effectively as I have been able to do.