I'm loving the switch over I've made from doing a paper copy to a GoogleDocs Form of student surveys for my classes. Now all the survey responses are online and easily searchable/readable without having to find the papers and remember them from years past.
I also have them do this in class after I discuss "constructive criticism" and "helpful comments" and the fact that I have found previous comments very useful and have even changed how I run class because of some comments. I think that if I didn't have them do this in class, many would forget to do the survey, and I wouldn't have enough information.
Here are the questions I ask:
Useful feedback so far. For example, I recently started uploading my flipped class videos a different way, and I wouldn't have known it was not as helpful if it were not for some comments kids made. I also try to keep my videos short, but some comments asked for my creating extra "showing examples" videos that would be optional. I think that is a useful comment.
And because I just copied this form from the year past and changed the name, I have last year's comments to refer back to to refresh my memory. Win. Win.