Colorado has five seismograph stations which are part of the PEPP (Princeton Earth Physics Program) network. With the aid of a National Science Foundation grant, we have been working on getting the stations running and expanding access to these data and the ability of teachers statewide to use them effectively. During the summer of 2001, we conducted a week-long workshop to train 25 high school teachers in Colorado to implement the Colorado earth science standards for grades 9 to 12 using seismology. The workshop was learner-centered, giving participants the opportunity to experience inquiry-based learning before implementing it in their own classes. This was accomplished by having participants work through hands-on seismology activities designed for their students. Participants worked in small groups, which were facilitated by a peer teacher who was trained prior to the workshop. Teacher-led groups (“teachers teaching teachers”) fostered learning among group members. Participants learned how to download seismic data from PEPP and IRIS (Incorporated Research Institutions for Seismology) and use software to analyze the data to increase their understanding of earthquakes in particular and the earth in general. A sample of these activities can be viewed at http://copepp.cnr.colostate.edu/. The following semester, the participants implemented the activities in their own science classes. We conducted evaluations during the course of the workshop and immediately after the teachers had completed implementing the activities in their own classes. Evaluation data indicated that the workshop was an effective teacher training mechanism and students of participating teachers found the activities engaging. Based on the evaluation data, we are working to improve both the workshop and student activities.