exactly what george zimmerman knew about florida s stand your ground law and when he knew it were the focus of today s murder trial. phil keating has the latest from sanford tonight. you see george over here? how you doing, george? reporter: george zimmerman s former criminal professor took the stand today after the judge ruled they can bring back his past passion for pursuing a career in law phone respectment due to zimmerman s own words played for the jury yesterday from a sean hannity interview a year ago. prior to this night, this incident, had you even heard of the stand your ground? no, sir. you d never heard about it before? reporter: but zimmerman s former professor who gave zimmerman an a says he lectured stens differen extensively about the self-defense laugh. the students were very much engaged in class discussion regarding the issue. reporter: but on