Here are two templates for recommendation letters for students^{1 2}:

1. It is my pleasure to formally recommend [Student.FirstName] [Student.LastName] for employment/admission with/to (name of employer or school). I have been a teacher/professor of (name of subject) at (name of school) for (number of years) and have been an educator for (number of years teaching in total, if different than previous number).
2. Dear Ina Burt, It is my pleasure to recommend [Student Name], whom I have had the privilege of teaching for the past [Number of Years] in [Subject/s Taught]. In that time, I have seen [Student Name] excel academically and display a dedication and confidence that is rare in a high school student.