One-twelfth of the students felt eye sore because of reading under too strong or too dim light.

Astronomically speaking, the twelfth house is that one-twelfth sector of the local sky just above the eastern horizon (see above picture) occupied by planets during the two hours after they rise.

It uses so much energy producing the slimy mucus and crawling over it that a mouse traveling the same distance uses only one twelfth as much energy.