When covering the process of cellular respiration, advanced high school and undergraduate biology classes present fermentation as a means of anaerobic energy production in certain organisms and in muscle metabolism. Although most biology textbooks cover aerobic and anaerobic processes in detail, this laboratory-based case study is designed to highlight the practical applications of fermentation. The beginning of the case study involves a story that students read and discuss in small groups in order to learn about the process of fermentation. The students then design a controlled experiment to test various juices for fermentation to predict which ones are preferred by yeast. Finally, they carry out a prepared protocol, then collect and analyze their data. This case study is suitable for advanced placement high school biology and college-level introductory general biology classes for majors or non-majors.