Watching Old Faithful transform from a smoldering mound to an explosive 50-meter high geyser is enough to generate awe in any observer. Geysers provide an excellent opportunity to explore th Earth system as described by the National Science Education Standards (content standard D for grades 5-8). By using the geyser model activity described in this article, students can investigate the relationship between the hydrosphere, geosphere, and biosphere. In addition, students will be able to develop descriptions, explanations, and predictions using the model as a guide for their exploration and apply their thinking to their local setting.