3-2 class (or 2-3)
There are a small but growing number of courses which vary even from this structure.
IMSA students have a fairly rigid set of requirements at a departmental level, but within each department (especially in math and the sciences), they have many options for meeting each requirement. The class requirements are as follows, along with the typical meetings times of courses in that department (for clarity the symmetric alternatives are omitted—e.g. “3-2” below means “either 3-2 or 2-3”):
Math: 3-2 for six semesters, though a small number of upperclass math electives are 3-0.
Science: two 4-0 classes for two (sophomore) semesters, but some classes can be tested out of, then four semesters of electives. Most electives are 4-0, but some are 5-0, and some are 3-2.