Working with data is a foundational concept not only for mathematics, but also for understanding the world around us. Readers will gain exposure to principles of measurement, such as measuring length and using it to perform operations, while other narratives introduce concepts of money and time. Bright visuals help make math not only concrete, but also fun. In this book, readers are introduced to interesting freshwater fish, while learning how to compare lengths. This volume meets CCSS Math Standard 2.MD.A.4.