The Look

Can I just say that I appreciate my class more when other classes have a substitute?  Yesterday, the class next to mine had a substitute.  Bad is not an appropriate word to describe that room.  Out of control would be a better description!  By the afternoon I couldn't take it anymore.  I just stood outside the door and glared at the students.  They quickly got quite and sat up in the chairs.  I went back in my room laughing at how a look can make such a difference.  Have you mastered your look?