It used to be called - "Specimen copy"—the evaluation copies of books that publishers give to the teacher. Some publishers used to stamp the book covers, saying Specimen copy. I have had many teachers in my family, and most of the books I read in school were Specimen copies. I always had a thing about it - it was a privilege. The books that no one else had. I have loved books since forever and I used to read books that were not part of my syllabus. Old UP board books of elder brothers and my parent's generation. College books of History and English literature, religious texts, anything that I can my hands on. I used to read preface, acknowledgements as well. But Specimens were specially unique. New and even less known books from publishers that I would have never heard of otherwise. When I was in school, I read several books from other publications than the one recommended in school. I used to look at the back cover of books to find out which other books to ask for! For each subject, I ended up reading several books! And I still feel that is the best way to study for a student.
When I started teaching myself and got "Instructors copy," for some books, it was like life coming full circle. The books came to me this time. Surreal. Difficult to explain... it was no easy task filling those shoes. :)