First, I need to state my credentials and then introduce any hobbies and what not to relate to the students on a personal level. Here is an example of how I would do this:
Hello Class,
I am a computer programmer by trade, and have developed numerous computer programs ranging from simple web pages to a complete eco system for a doctor's office that covered every digital aspect of a doctor's private practice, but teaching is my real passion. There is nothing quite like the feeling I get when I see the light of recognition go off in the eyes… >>>