Each volume explains its subject’s location, parts, and function. Oversize text in short paragraphs; “Fast Facts” text boxes; kid-friendly, tongue-in-cheek headings, such as “Passing Gasses” (Lungs); and guiding questions keep the content engaging. The controlled vocabulary uses appropriate technical terms or provides a workable substitution. The design is cohesive and friendly. Numerous visuals, including diagrams, drawings, and color photographs, fill the pages. . . .