One of my students is applying to Caltech for a PhD. He asked me for a recommendation letter. I haven't written a recommendation letter before. He is a bright student and I want to help him.
On Caltech's website, there are five questions a recommender needs to answer. The last one is "How does the applicant compare to any previous students who have come to Caltech for their graduate work?"
However, no one from our department ever applied to Caltech. My university is a well-reputed one, but the department is small. Most of the students either choose to pursue a PhD domestically or go for industry positions. Applying for PhD in the US is unheard of. That's why I'm very keen on recommending this student as he is breaking barriers and is the first in our department with such ambitious goals.
I do know that on a letter, it wouldn't look good if I mention that none of our students have joined Caltech. How should I answer this question in a positive light that would be helpful for my student?