Teaching has always been more of a vocation than a profession. Every responsible citizen of the world was once moulded by a good teacher. It takes a special skill to impart knowledge to another person, be it a child or an adult. That is what makes teaching an art—knowing what level your learners are at, and presenting the material to them in a way they will not only grasp and remember, but be able to make practical use of.
This is the first teacher training MOOC on edX.