Many of us have encountered cohort groups in our teaching, and by that I mean those groups of students that proceed together through a program, typically a professional one. They take all or most of their courses together, often in lock step. Cohort teaching happens to some degree in most courses. Students in a major at smaller institutions often end up taking many of their courses together. Sometimes there are cohort groups within a class, say a group of commuter students who went to the same high school, or students who live on campus in the same residence hall, or a group of adults taking a work-related course.