Format your letter according to standard business letter standards. Include your name and the address of your academic institution in the top right of the letter, the date and business address of the publisher below your address on the left side, and a standard salutation such as "To Whom it May Concern:" or "Dear So-and-so,".
Indicate your position (high school English teacher, college Chemistry professor) as well as the educational institution for which you work (San Mateo City High School, Penrock State University).
Describe the book you are requesting through the letter. Include the title of the work, the author, as well as the International Standard Book Number, which is located above the barcode on the back of the book. Oftentimes ISBNs can be found on a publisher's website or through a third-part online bookseller.
Articulate your reason for requesting the book. Though some publishers accept answers such as "for my personal research," the most standard and accepted response is to indicate that you are considering the book for use in a class you are teaching.
Close your letter according to standard business letter conventions. Thank the publisher for their time and consideration and sign off on the letter with "Respectfully," or "Sincerely," before signing your name.