Statistics is a branch of science that deals with the collection, analysis, interpretation, and presentation of numerical data. We use statistics every day to solve problems. Geneticist Gregor Mendel, for example, experimented with pea plants, which led to the development of theories of dominant and recessive genes. Similarly, teachers use statistics to average classroom grades to determine what students have learned as a result of classroom instruction. In this chapter, the authors demonstrate how you can use the powerful tool of descriptive statistics in your classroom to help you summarize, organize, and simplify data.