This book addresses the question posed in its title: do teachers of content other than language arts really need to teach their students how to read in their content areas? Not surprisingly, the author's answer to that question is a resounding "yes". Somewhat surprisingly, she makes a good enough case for that answer that many if not most readers of the book will be persuaded.
Reading a math textbook (or other math instructional material) or science, or history, or even industrial arts, all require different skills than reading a novel, and for the most part, different from each other. Each content area has its own jargon, its own standard methods of expressing its concepts, and its own priorities in terms of what students need to be looking for when they read. A student who is a good reader of literature may or may not be able to figure out, on their own, how to transfer those skills to the reading of other content areas. Some will manage it, others will need explicit instruction. It is the job of the teachers of those content areas to make sure that their students are given that explicit instruction. Some strategies and skills will have value for several areas; some may even apply across the board. But it's important for teachers to help students see how reading in their particular content areas differs from reading elsewhere, and what strategies will NOT apply. It seems obvious to say that looking for plot, characterization, and symbolism, while helpful in the reading of literature, will not be of any use in reading a math or science text, and students probably would not consciously do so. But if that's how they're used to approaching a reading assignment, they may find that they have no skills to replace those with in order to make sense of their assignment; they may not be aware that that lack is what is making the reading difficult. That's where explicit instruction comes in: point out to them how they are used to reading and the obvious ineffectiveness of those skills to the job at hand, and then give them some suggestions of approaches to replace those with.
This is the gist of this book, and it's a very good point that needs to be made. What's more, the book is written in a very accessible, conversational style, with a minimum of ed-psych jargon. It contains many helpful suggestions of ways to help struggling readers, both in general and in regard to specific content areas. Highly recommended.