I often get approached by students asking for a letter of reference. To be honest, merely being asked is often a wonderful validation of how the student in question perceives you. And writing a letter of reference (an art in itself) is a joyful exercise when you know the individual well and believe in their abilities. But too often the student is simply one name amid a class of 200. They might have done well enough in terms of their grades in the course, but often they have never visited my office hours, hung around after class for a chat, or even participated actively enough in class to stick out in my memory. What to do then?
In these cases I typically advise the student that, given our limited personal contact, any letter I write could only really discuss their performance in the course (interpreted via formal, summative assessments). Of course, I could include information also listed in their cv, but none of this amounts to the kind of reference they really need (or are hoping for). I believe the ethical approach here is to be open and honest with the student and then let them decide. A letter from someone who knows them well enough to comment on their character and performance over a longer period of time is far more valuable (having been on the receiving end of many letters of reference I can also attest that a lukewarm letter of reference is often rather damning). In short, the question they should ask me is not “would you please write me a letter of reference?” but instead “do you feel you could write me a strong letter of reference?”