We have developed and implemented, over four semesters, a model for engaging computer science majors in service learning for teachers of grades 6-8 at a K-8 school in an underserved community. This paper describes the design of a course focused on interweaving software engineering practice, service learning, and development of "soft" professional skills. CS student teams partner with middle school teacher teams to create learning games for classrooms, and then conduct classroom instruction and observation. We report on our results from evaluating the experience of CS students and middle school teachers through pre-post surveys, evaluator observation of student demo presentations and classroom instruction, focus groups, and student reflective journals.