I'm applying for master's programs in ecology. I'm finding that when professors advertise looking for students, they are asking you to send them your CV, transcripts, test scores, and a "letter of interest." (Submitting this stuff to the potential advisor is separate from submitting your application package to the grad school admissions office.) I'm not really sure what a "letter of interest and qualifications" is supposed to look like. Like a cover letter for a job? Or more like a statement of purpose/personal statement? I'm leaning toward the former (something a little more conversational and addressed directly to the professor in the second person, not in the tone of a writing sample or essay) but I'm not sure. Any thoughts? Thanks.