Pages 1-15 are the introductory text, covering the origin (and usage) of the word Pentateuch, comparing and contrasting the penta-, hexa- or ennea- teuch, and a general overview of the Hebrew bible.
The second chapter (pages 16-39) provides overviews of each of the books of the Pentateuch.
In total, these two chapters overview the canonical Pentateuch and answer some basic questions the reader might have.
In terms of identifying an insight, read over the preface. It details why this book was written: the recent resurgence in academic studies of the Pentateuch. Did you have any of the questions that are covered in Chapter 1?
Were you intrigued by the etymology of the word? Were you interested in the historical events and interpretations that have altered its use?
In order to construct your five sentence paragraph, think about these questions:
1. identify the most interesting part of the reading
2. why did it interest you
3. does it contrast to what you believed/thought previously
4. how has it changed your outlook
For example, do you agree that Genesis-2 Kings should (or could) sit as a single, separate, literary work?