This chapter focuses on reading the earth in the atoms. Activities are considered that can engage students at the “classroom-friendly” end of the learning spectrum. Understanding geochemical cycling and the differentiation of matter in planetary systems rests on two classroom-size ideas, mass balance and chemical partitioning, which is addressed in this chapter. A geochemical differentiation by means of an experimental investigation into how the concentration of salt changes in water as the water evaporates is featured in this chapter. When you examine geochemical cycling in the classroom, it is suggested to do a small-scale, specific study appropriate for the classroom first. A materials list, teacher background information, safety practices, and outcomes are provided. This book selection includes the Table of Contents, Acknowledgments, About the Authors, About the Book, Introduction, and Index.