westside has used a modular schedule since 1967. each module, or "mod" (as known colloquially among whs students), is either a 20 or 40-minute period used for classes or independent study time in an instructional materials center (imc). this allows freedom in scheduling as classes can be 40, 60, or 80 minutes long, as needed for one-to-one, small group, large group, and laboratory instruction. classes are taught in a similar format to many universities; students meet a large group lecture once per week and have small group recitations throughout the week. an average student has at least one or two full open mods per day, to be used for studying, interacting with teachers, eating lunch, or socializing. juniors and seniors who have met specific requirements are eligible to apply for a pass that allows them to leave the building during open mods.