I think the most important thing for a professor/teacher is to present the material you teach about in a way that people understand. That’s actually very difficult. It’s relatively easy to make people memorize things – I can write down equations and ask people to please remember them. But that’s not the point. Students don’t need to remember everything if I can make them understand the underlying concept. I try not to just write down an equation and tell people, “this is the equation”; I try to tell them where it comes from and why the equation looks the way it does.