Murphy's Law on Observations

My principal had orginally planned to observe my class two weeks ago and had asked for the lesson plans in advance. I wanted to make sure I was well prepared, so I created some outstanding lesson plans that included almost every "tool" in my my toolbox. Well, wouldn't you know, it ended up he couldn't observe during the designated time frame! He came to me last Monday and told me he would be in my room the next day. I decided that maybe the principal would be impressed with my plan to review and discuss the most missed questions from the previous day's test. I thought that this would be a great demonstration of my skills in remediation and mastery of concept. And I could count on my third year students to contribute and develop productive conversations. The class began, the principal walked in, and the class that is always "involved in the learning process," TOTALLY clammed up! They huddled in a corner like refugees, kept their mouths shut the entire time (leaving me to do all of the talking), and at the same time, they were cutting their eyes at the principal in the corner. When he left, I had to fight the urge to run after him down the halls telling him, "they're not usually like this!! Come back! Come back!" What's that saying about the best laid plans?????????