In this lesson, it is assumed that students have had some encounter with the water cycle previously, but may not understand the important role of groundwater in the cycle. Karst terrain provides a hook for studying groundwater, for thinking more deeply about the effects of the water cycle, and for tying this topic to other topics in geology. Students will begin with a two-part activity where they make a model of groundwater and think about the role of groundwater in the water cycle and where they examine limestone samples to look for the characteristic carbon dioxide bubbles that are released when limestone reacts with an acid. The reading strategy featured here is “talk your way through it.” A materials list, teacher background information, references, assessment, and outcomes are provided. This book selection includes the Table of Contents, Acknowledgments, About the Author, Image Credits, and Index.