class change; class shuffle; rearrangement of students into new classes
Refers to the annual school event where students are reassigned to different homeroom classes, typically at the start of a new school year in Japan.
Next month there's a class shuffle, so I'm excited to see who I'll be in the same class with.
The results of the class rearrangement were posted on the bulletin board.
Compound of クラス (class) and 替え (change, replacement), from the verb 替える (to replace).