Hmm... So, in Korea, the students can't go home before the homeroom teacher specifically comes to send them home? Or was it a self-study session as the last thing before the school ends, and that's why it happened like this, to make sure no student simply walks home after 10 minutes of "studying"? I find it peculiar because you'd think it would be more efficient for the last teacher to simply send the students on their way, not the homeroom teacher specifically. But then again, this sort of very strict and formulaic homeroom system doesn't exist in my corner of the world, so I wouldn't know.