<iframe width="420" height="315" src="//www.youtube-nocookie.com/embed/4g-pgsSZCIY?rel=0" frameborder="0" allowfullscreen></iframe>
Dr. John Mortensen, Professor of Piano at Cedarville University, explains the principle of rotation. It solves lots of problems and sets pianists free, but the majority of students do not understand it. Here's how and why.
