Earth's easily seen surface features (mountains, volcanoes, and islands)--and the movement of the tectonic plates that lie below--offer hints about the processes that produced them. Inquiries in seismology, the study of earthquakes and other ground movements, can help students learn about Earth's geologic processes. This article describes an activity that uses "guided inquiry-based teaching," in which students form their own questions based on data, observations, images, and text so that they can formulate their own hypotheses. Students use classroom seismographs to detect, observe, and evaluate earthquakes and other ground motions and then create their own seismicity maps. With their own data, along with official seismicity maps, students arrive at evidence-based hypotheses about geologic processes.