Those who can do...those who can't teach doesn't apply to Sensei!! I think Cato summed it up the best and I agree 110% with everything he said. I personally teach by concept, not so much technique. I include principles and basics and teach the 'how and the why' things work or don't work. Teaching has made me very technical and it helps when we go full speed. I highly agree about breaking things down to a simplier level, this is a great thing to be able to do. But........What I would like to offer is a bit different. You have heard great reply's so I won't repeat what has already been beautifully said. But one thing I find that teaching does, is the ability to 'think' on your feet, when questioned by a student. Being able to explain things on levels, as the Shodan doesn't get the same answer as a 2nd kyu or the same as a 6th kyu or a 6th Dan. Alot of times, beginners can catch you off guard with questions, and you have to think on your feet. Also, someone may tell them 1 thing(even within the dojo) and you may give a different answer, now they want to know why the 2 answers. The ability to deal with this gives one insights to what they do. we teach basic blocks, reverse punches, basic locks, to beginners, but when they reach Black Belt we start giving them a different way to see what they do. Here come the questions. A Sensei needs to be sensitive to his students needs and questions, and only if you teach can you learn these things