The science class rooms (biology, chemistry) were also favored rooms, since they had attached storage rooms that were off limits to students.
Based on the smell test, it was obvious that my biology teacher always had a smoke between classes -- and most of us believed that she had a personal bottle in there. She was tough as nails, but she was not ready to except minimal performance, and those of us who had her learned biology!
For a while there, we thought that us students were going to get one too! Didn't happen, but we tried.