There is a misconception that teaching and performing music do not go hand in hand, that it is not particularly necessary for a music instructor to be a good performer. Nothing can be further from the truth.
Imagine if this concept existed in other fields. Unfortunately, it does with some people, who cannot seem to realize the connection. How can one teach another to swim, for example, if he is not a swimmer himself? A swimming instructor needs to be a proficient swimmer, otherwise he risks his student drowning. Incidentally, he usually has to be a trained lifeguard as well. A music instructor has to be just as proficient in his own field. Just as a lifeguard can rescue his student with proper methods from potential drowning, a music instructor can rescue his student from going wrong.
A music instructor has to have sufficient knowledge, ability and experience to perform.
Most important is the instructor’s ability to perform. In schools of music, when one is earning their degree, it is common for them to not only give a mandatory recital, but to also demonstrate to the jury how to teach as well, usually with several pieces. The principle here is that if one is able to learn himself, essentially to teach one’s self, then he has what it takes to teach others. They go hand in hand.
We are not just talking about those who are highly professional. This applies to anyone and everyone teaching or learning music.
It is actually mandatory for most music professors to perform once per year in order to keep their positions in their university.
There are two main reasons why music teachers do not perform: 1) They don’t know the instrument they are teaching well enough. Example: A teacher teaches piano, which they have learned as general music knowledge in a school of music, so they are not experts in that instrument. 2) They know their instrument, but they claim they don’t have time to practice it in order to maintain their proficiency. Truthfully, this is just a matter or professionalism. A person can be a medical doctor, for example, but can be very versed in violin, even giving recitals and playing in orchestras. It is not their vocation, but they still find the time. Professional actors, regardless of their skill and fame, routinely take master classes. Truly professional musicians will do this to some degree too.
Sometimes, the allure to make easy money tempts some people to teach without being properly able musically. Unfortunately, society allows this due to its ignorance of this matter. That’s why there are hordes of music teachers who seem to offer enlightenment, but are factually quite limited.
A student should first hear their instructor perform, whether live or recorded, before even considering them.
It is also somewhat of a prestige for a world-class performer to contribute and teach others.