The former "Who's the Boss?" and "Taxi" star is filming an A&E reality show called "Teach."
He's co-teaching an English class of 26 sophomores at Northeast High School with a credentialed teacher.
Danza spoke to parents at the school his first day Tuesday, reassuring them that he's qualified to teach because he's in the process of becoming certified and has spent months preparing.
He writes on his blog that he was scared his first day. He decorated his room with motivational sayings, including one that said: "No moaning, no groaning."