- Teachers never leave the school grounds. Ever. They stay there overnight, thinking up new and interesting punishments for the children that they just have to tell everyone about. They shout it from the noticeboard, laughing maniacally. This is a fact. All pupils have been talked about in great detail. Teachers don't need their spare time during school hours for anything else.
- Teachers do not sleep. There is no need to sleep when you have lived for thousands of years. The body becomes changed, less human. Teachers can use this time to correct the multitude of errors found in the homework of their pupils. Teachers enjoy nothing more than repeating the same lessons of 'there', 'their' and 'they're', and so on.
- Teachers spend the weekend thinking up new ways to punish their students. There is nothing better for a teacher to do than to find new and interesting ways to make someone suffer. After all, teachers are all sadists.
You can totally trust me on this one. I've been in a staff room, hooked up to the mainframe* and interacted with most of the staff in a school. It's definitely all true.
*Staff rooms are the inspiration for the Borg in Star Trek.