Ann Patchett said this quote
“ Questions are for the benefit of every student, not just the one raising his hand. If you don't have the starch to stand up in class and admit what you don't understand, then I don't have the time to explain it to you. If you don't have a policy against nonsense you can wind up with a dozen timid little rabbits lined up in the hall outside your office, all waiting to whisper the same imbecilic question in your ear. ”