Nearly all graduate school applications require the submission of three or more letters of recommendation on behalf of each applicant. It is the rare applicant who can easily think of three professors to ask. Instead most graduate school applicants find it easy to obtain two letters, one from their primary advisor and another from a professor with whom they have worked or taken multiple classes, but the third letter often is a stretch. Applicants often must turn to faculty with whom they have had less contact in order to obtain a third letter of recommendation.
Can you write a helpful recommendation letter?
What happens if you're that professor? What if a student approaches you, but you've known him or her in a small capacity, perhaps only as a student in only one of two of your classes? You may have a very strong positive opinion about the student yet the strength of a recommendation letter lies in its details. Do you know enough about the applicant to write a letter with sufficient detail?
A helpful letter of recommendation includes examples to support every positive statement made on behalf of the applicant. A strong recommendation letter not only explains that an applicant has excellent problem solving skills but provides examples. If your only contact with a student is in class it might be difficult to support such statements.
Alternatively you might instead discuss the qualities that you have witnessed and extrapolate from what you know to make inferences about the students' out of class competencies. For example, you might generalize a student's success in analyzing case studies to draw inferences about complex thinking in everyday contexts. In addition you might discuss how the skills you see in class support the students' out of class accomplishments, for example in conducting research with one of your colleagues.
Pause before making a decision.
Whenever a student - any student - requests a recommendation letter you should pause before responding. Quickly assess what you know about the student and determine how supportive you are of his or her academic intentions. If you've worked closely with the student it shouldn't take more than a moment to make a decision. It's more difficult if you know the student only from class. That said, lack of outside of class experience with a student should not stop you from writing a letter if you have good things to say and can support them.
Inform the applicant.
Just because you can write a letter on behalf of the applicant does not mean that you should. Inform students about the purpose of recommendation letters, what makes a good recommendation letter, and how your letter, while positive may not offer the types of details characteristic of helpful recommendation letters.
Remember: Nice isn't nice.
Not every student who asks should receive a recommendation. Be honest. Frequently professors receive requests for letters from students who were little more than names and faces. If you have nothing to say about a student other than he or she attended class and earned a grade your letter will be of little help. Explain this to the student. It may seem "nice" for you to write a letter but writing a recommendation letter that says nothing other than what appears on the transcript is far from nice and will not help the student. You are doing them a favor by refusing a letter.
Should you give in?
Sometimes students will be pushy. Students often struggle to find that last recommendation letter and may ask for your letter regardless of your warnings. Some faculty give in. They again explain the content of their letter and that it is not helpful, but agree to submit it. Should you give in? If your letter only includes course grades and other neutral information you might reconsider and submit the letter as long as you have explained the ramifications to students. Some professors argue, however, that it is unethical to send a letter that you think will help the student gain admission to graduate school.
It's a tough call. If the student's only choice for a third recommendation letter is a neutral letter and he or she understands this as well as the content of your letter, writing the recommendation letter is likely your best choice.