This unit introduces students to the foundation of statistical thinking by exploring how data are described and summarized. Students learn to distinguish between quantitative and categorical variables, create and interpret graphical displays like boxplots, and calculate measures of center and spread. Building on this, they are introduced to the normal distribution, understanding how z-scores represent relative standing and how probabilities can be computed using normal models. Together, these chapters develop students’ ability to see patterns in data and apply fundamental concepts that support deeper analysis throughout the course.