In schools without lockers, students are sometimes provided with two complete sets of textbooks, one set being kept at school for use in class, and the other being kept at home for referring to for homework, thus limiting the amount of heavy carrying that would otherwise be required without having lockers to store them in between classes. However, research has shown an increase in the incidence of back injuries in some students, which has been directly attributed to the lack of lockers for storing books in, thus forcing students to spend more time carrying heavy loads of books in backpacks.
Bank size: It does not necessarily refer to the total number of compartments, but rather the number of compartments wide the entire cabinet is. So a bank of three may contain six lockers, for example, if they are two-tier lockers. In short, the total number of lockers is the bank size multiplied by the number of tiers. Sometimes the term "bay" is used instead of "bank", although "bank" appears to be the more standard term; on other occasions, "bay" refers to a single locker width within a bank, including all tiers of locker directly on top of each other.