A fabulous read!  This collective biography introduces readers to twenty famous scientists who shaped the history of human understanding.  The collection does a good job of drawing from a variety of cultures and scientific disciplines, going as far back as China in the early years of the Common Era.  It includes the famous names students are likely to have heard of (but may or may not know much about), such as Galileo and Newton and Einstein, as well as many that were new to me (e.g. Zhang Heng, Ibn Sina, William and Caroline Herschel).  For each scientist, the book provides the basics of the significance of their discoveries, but the main focus of the book is adding personality to the names, to get the sense of what kind of person each was, giving context to their lives and their work.  It’s very readable and interesting.  Elementary librarians should be aware that some parents may complain as their are a few references to some of these great names having extra-marital affairs, but such references are brief.