To the Twitter-illiterate: The Anatomy of a Tweet. This infographic will clear things up for you right away so you can understand what you're looking at when you're reading a tweet.
This is another great way to learn how to make twitter into an educational learning program. It breaks it down into steps and shows you what everything means and what it is used for.
A word or phrase preceded by a "#." How do hashtags work? Twitter can be a busy place with lots of tweets-and thus lots of "noise." A #hashtag is a way to aggregate tweets that are appended with a hashtag. Picture it like a magnet that attracts all messages categorized by that topical word or phrase. Also this website offers great resources for every possible class a teacher could teach.
This article gives insight to why teachers should be using twitter in the classroom and the benefits this social networking website brings to your students and the content they are learning.