Class association numbers group all class sections that constitute a single offering together. Courses that have a combination of components (e.g. lecture, lab, activity, etc.) that must be taken together share the same association number. Generally, students must register in one of each of the listed components. For example, BIOL 104 has two lecture sections and several lab sections. Students must register in one lecture and one lab from the group of sections that have the same association number.