It is a challenge to convey any nonfiction concept at a beginning-reading level, but author Pettiford succeeds at this in the Science Questions series (4 titles). Each book focuses on one very basic answer to its title question. The brief text, aimed at early readers, is strongly supported by well-chosen, labeled photos that break down the science and a final infographic that depicts the concept as a complex whole. Why Is the Sky Blue? introduces the light spectrum, focusing on blue light-waves' short length and high visibility. The books seem intended for an educational setting, with before-, during-, and after-reading questions provided in the front matter and a concluding summary, a four-item picture glossary, and a half-page index in the back matter. A simple introduction to common science queries for the youngest readers.