This teacher's guide, with accompanying videotape, presents an episode of the NASA SCI Files. In this episode, one of the tree house detectives has had an accident and cannot get into the tree house. Using problem-based learning, the rest of the gang investigates the world of simple machines and physical science and "pull" together to get everyone into the tree house. The scientific concepts addressed in this episode include numbers and measurement, geometry, data analysis and probability, problem solving, communication, representation, unifying concepts and processing, science and inquiry, life science, earth and space science, science and technology, history and nature of science, the world in spatial terms, places and regions, physical systems, human systems, and environment and society. The guide is divided into four segments with the following sections: overview; objectives; vocabulary; video component; careers; resources; and activities and worksheets. (YDS)