In the early twentieth century, a curriculum known as nature study flourished in major city school systems, streetcar suburbs, small towns, and even rural one-room schools. This object-based approach to learning about the natural world marked the first systematic attempt to introduce science into elementary education, and it came at a time when institutions such as zoos, botanical gardens, natural history museums, and national parks were promoting the idea that direct knowledge of nature would benefit an increasingly urban and industrial nation. The definitive history of this once pervasive nature study movement, TeachingChildren Science emphasizes the scientific, pedagogical, and social incentives that encouraged primarily women teachers to explore nature in and beyond their classrooms. Sally Gregory Kohlstedt brings to vivid life the instructors and reformers who advanced nature study through on-campus schools, summer programs, textbooks, and public speaking. Within a generation, this highly successful hands-on approach migrated beyond public schools into summer camps, afterschool activities, and the scouting movement. Although the rich diversity of nature study classes eventually lost ground to increasingly standardized curricula, Kohlstedt locates its legacy in the living plants and animals in classrooms and environmental field trips that remain central parts of science education today.