Burlington High School principal. It is a retweet of a link to an article about math education. This article was retweeted extensively by teachers and administrators who felt that it "really resonates". The administrators who tweet and share with one another are real leaders in their field. They are not followers; they inspire their staff to take reasonable risks who inspire students to greater learning.
We still hear the question of "why tweet?" when to me it is obvious. In a world that changes so rapidly, I could not keep up without my network of friends, my "PLN". As the screen grab shows, twitter is great for rapidly sharing information, links, articles, and comments. Comments back and forth turn into a conversation.
The list below was compiled by Cybrary Man and is part of his personal learning network. Cybrary Man also has a great collection of internet catalogue of educational websites. Is your principal in this group?