This design case chronicles the efforts of an interdisciplinary team of researchers as they collaborated with middle grades science teachers and students to build and refine an epidemic disease curriculum module. The initial five-day design was delivered in five science classrooms at three nearby schools where researcher classroom observations and teacher feedback drove iterative refinements of the module's materials. The final design of this module consisted of four instructional days of modeling and simulation activities that integrate computational thinking practices, computer science concepts, and life sciences content. The paper aims to illustrate the design motivations to address contextual constraints such as tight curricular schedules and varied levels of exposure to programming for both teachers and students. The instructional materials presented in this design case were the result of a three-year long research-practice partnership with science teachers at nearby middle schools.