Gr 5 Up-These titles focus on two inventions that changed the course of history. Meltzer briefly explores the lives of the men most closely associated with them, Eli Whitney and Johann Gutenberg, respectively, and delves into the historical context that led to the development of the machines. In Cotton Gin, the influence of mechanized cotton processing on the growth of slavery in the United States and the increase in textile mills is documented. The author makes the case that the greater volume of cotton production required more people to harvest it and work in the mills built to handle the increase. In the second title, Meltzer emphasizes the more positive outcomes of the printing press. Science, religion, democracy, and exploration all benefited enormously from the widespread dissemination of information and knowledge that followed the advent of movable type. In both books, the author expertly describes a setting that is ripe for invention. Powerful photographs (Cotton Gin), historical artwork, and personal narratives make the times real and relevant to readers. The bibliographies and the further reading in Cotton Gin are helpful additions; however, several suggested Web sites were not functioning at the time of this review and quotes are not fully documented. Students will find the books accessible, and the primary-source material makes them strong choices for reports and general classroom use.-Jody Kopple, Shady Hill School, Cambridge, MA Copyright 2004 Reed Business Information.