Not your favorite class, but your favorite topic. I haven't taught much (only tutoring and student teaching), but my favorite was teaching matrices and their relationships to solving systems. It was great to show them the tricks after they spent so much time calculating the systems by hand. I am a little disappointed they aren't being taught in algebra 2 any more, but I'm sure I'll love some other topic just as much. What is your favorite topic to teach? What class do you teach it in?