every week; weekly

water aerobics, aquabics

Friday

(software engineering) class diagram - A type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, and the relationships between the classes.

participation, commitment

to participate, to join, to enter

(education) class (group of students in a regularly scheduled meeting with a teacher) / class of things (typically products) sharing certain features / (programming, object-oriented programming) class

(aviation) economy class

first class (a status, section, etc. of premier rank)

business class