I caught my Macro professor doing this and it works wonders. It really encourages people to ask questions, even if they might think they are inane. He always started with a ~sincere~ "X, that is a really good question." It makes everyone feel really welcomed to give their input no matter how small. Even though it might not be "sincere" at all it still feel like it is. How would you feel if you asked a question in class and the professor said: "That's actually a really stupid question but I'll answer it anyway."

Good job.