This paper describes an innovative assessment method that provides formative feedback on the effectiveness of an engineering textbook. We describe the development of the Text Learning Capture Method and the prior art that it is drawn from. We then go on to interpret and analyze the protocols captured with the method and describe the preliminary results generated with its application. Concrete examples of how the feedback enables us to identify the text's readability, comprehensibility, and usability are given. From the analysis a list of questions was generated about how students learn from engineering textbooks. The textbook assessment work presented here was motivated by a desire on the part of the author of the textbook (hereafter the text-author in contrast to the authors of this paper) to understand more fully the role of this textbook in supporting student learning. We began with questions such as: "Do students relate to the real-world examples given?"; "How do students work through the equations?"; "How are figures utilized?"; "Are students excited by a textbook that uses a familiar multi-faceted artifact to demonstrate engineering principles?". In our attempts to carefully answer these questions we generated questions such as: "Can learning from a text book be thought of as passive?"; "What constitutes effective learning from texts?"; "What are best reading practices?"; and "How much control does an author have over this?".