Quite true. Best way to learn is to teach. I learn more when I
   try to explain than I do when studying. I live by this. As soon
   as I think I understand something, I try to explain it quickly
   to somebody else. Doesn't matter where. I judge by the responses
   whether I think they 'get it' but really, to be selfish, it's
   not whether they get it or not. It's whether I'm satisfied with
   how I explained it - the feedback though helps me find out if my
   self-assessment needs tweaking or overhauling.