Introduce your position and how long you have worked with the organization the student worked for. You may also note how many other volunteers worked for the organization or the organization's history with student volunteers over the years.
Discuss the student's volunteer role in detail. Even though the student may note that she worked for the organization elsewhere on her application or personal statement, this is an opportunity for you to provide an admissions committee great detail on her experience. Reference each project she worked on and her contributions to each in your letter, being as specific as possible.
Detail the student's growth from the beginning of the volunteer experience to the conclusion. Note how you witnessed her expertise, professionalism, team work or knowledge in a particular area expand. You may say, "When Julie first began, she was relatively green to the concept of sustainable practices. However, at the conclusion of the internship, she was able to discuss various practices with ease and comfort."
Give an overview of the student's positive qualities. Note the student's ability to be a team player, a good communicator or extremely passionate, for example. You should also provide specific moments during her volunteer experience that these qualities were apparent.
Write that the student's volunteer experience will allow her to contribute to the college she is applying to. If the student is applying to major in a field related to their volunteer experience, note that you believe she will utilize her experience to contribute to classroom discussion. Alternately, you may detail your belief that a student's personality or character traits make her an excellent match for the school she is applying to.