Many traditional science curricula explore human body systems separately, paying little attention to how the systems interact. For example, the textbooks "Biology" (Miller and Levine 2006) and "Biology: An Everyday Experience" (Kaskel, Hummer, and Daniel 2003) detail the structure and function of each system and individual organs but offer little about the relationships among systems. This is problematic because understanding those connections is required to develop a holistic understanding of the human organism and because those interactions have practical applications, such as understanding how diseases can affect more than one body system at once. One effective way to teach connections among body systems is a problem-based approach. Problem-based learning is focused, experiential learning (minds-on, hands-on) organized around the investigation and resolution of messy, real-world problems. This article discusses an activity that helps students understand the relationships of various body systems in the common event of eating a cookie. The authors pose a question--"Why do I crave that cookie?"--that requires students to apply what they've learned about how body systems are integrated. Though the focus is on the digestive system, the main task is to understand how other body systems, including the senses, interact in the digestive process. In this article, the authors provide background knowledge students will need about body systems involved in digestion. Then they describe a possible teaching strategy to help students understand the integration of the systems. (Contains 3 figures.)