I am applying for grad school this year and I am considering sending an email to ask a professor to write me a reference. He had previously agreed to write me a letter because I took one of his advanced courses.
I am not sure if it'd be okay for me to offer to provide a template to him for the letter. The reason I want to do this is I will be applying for a PhD in a different, though quite related, field, and I want to make sure that he knows what the advisory committee will be specifically looking for in his letter, and make sure that his letter corresponds well with my statement of purpose.
Is this an acceptable practice between professors and students? Or would they consider it offending since he is supposed to provide his independent opinion? And if it is okay, how can I offer it in an appropriate way?