Short and sweet . . .
To whom it may concern,
This letter is a recommendation for Mary Smith to attend __________________
She was a student in my class, _____________________ during ___________________. In that class, I found her to be __________________________, and ______________________. Her work was _____________ and _____________________. One of her outstanding attributes is ________________________.
I feel she will make a fine student at your institution. For more information, contact me at the above address.