The NASA SCI Files is a series of instructional programs consisting of broadcast, print, and online elements emphasizing standards-based instruction, problem-based learning, and science as inquiry. The series seeks to motivate students in grades 3-5 to become critical thinkers and active problem solvers. In this program, the tree house detectives feel a strange tremor and begin to think that an earthquake has occurred, which prompts them to investigate plate tectonics and earthquakes. As they begin the investigative process, the detectives get a little help from Michael Lyle, a seismologist at Tidewater Community College in Virginia Beach, VA, Heidi Stenner of the United States Geological Society (USGS), and David Whitman at the National Dinosaur Monument in Utah. They also visit Dr. Carol Tang at the California Academy of Sciences to "experience" an earthquake. Mr. Ron Baalke and Dr. Andrea Donnellan at NASA's Jet Propulsion Laboratory (JPL) help the detectives come to an amazing discovery as they realize that plate movement is not the only thing that makes the Earth tremble. Johnny Alonzo, who stars in "Dawson's Creek," is the celebrity guest for this episode. The guide features vocabulary, careers, resources, and activities and worksheets. (KHR)