In this companion to the "NASA SCI Files[TM]" episode "The Case of the Physical Fitness Challenge," the tree house detectives learn about anatomy, fitness and nutrition in preparation for the President's Challenge. The guide is divided into four segments aimed at grades 3-5, each of which includes an overview, a set of objectives, vocabulary to be learned, a video component, related careers, resources, and student activities and worksheets. Guide includes a table indicating how each segment meets national standards for science, mathematics, technological literacy, geography, and health education. [NASA SCI Files[TM] is a collaborative endeavor of NASA with the following organizations: The Society of Women Engineers; Busch Gardens, Williamsburg; The National Space Biomedical Research Institute; knowitall.org; Apple Learning Interchange; ibiblio; and Hampton City Schools.]