This instructor's guide is written to accompany to the fifth edition of Understanding Fiber Optics by Jeff Hecht, originally published by Pearson/Prentice-Hall in 2006 and later republished by Laser Light Press. It is being published now to help readers using the book in self-study of fiber optics, because nothing like it has been published since then. It includes answers to quiz questions and "questions to think about" in the book, and worked-out calculations for many of the problems in the book. It also include suggestions for teachers on how to present material in the book, an explanation of the structure of the book, and supplementary material including references and links available when the fifth edition of the book was published in 2006. The author has not tried to update links other than his own.