K-Gr 4—With glossaries at the beginning, simple narratives, and plenty of color photos of nature and children at play, this series distinguishes itself from similar sets. In each volume, a diagram explains the Earth's rotation and tilt and how that creates the seasons. The titles then go on to explain how different seasons affect animal behaviors, the rudiments of plant photosynthesis, and other salient aspects of the natural world. Words of interest are highlighted throughout and defined in the glossaries, and diagrams clarify weightier concepts. The photos, though kid-pleasing, are sporadically captioned and sometimes only vaguely relevant to the texts. Experiments at the end guarantee reader engagement. Spring, for example, invites students to measure their shadows over the course of a day.