The term SCHOOL DAY DIVISION can be broken down into two crossword solutions: PERIOD (6 letters) and CLASSPERIOD (11 letters). A PERIOD is a length of time, usually measured in minutes or hours, and is commonly used to refer to the length of a school day. A class PERIOD is a specific block of time within a school day that is dedicated to a particular subject or activity. Class periods are typically divided into 45-minute or 50-minute blocks, depending on the school's schedule.