There was once a jiujitsu black-belt (no names, no names) respected by students and teammates, but who was unhappy.
Suspecting that the problem was the city in which he lived, he migrated from Rio de Janeiro to the United States, where he opened a new gym. He remained unsatisfied, and went back to teaching in Brazil, in another town.
But his mind quickly began planning moving to Europe, maybe Bali or Hawaii. Until he finally realized. What he really liked was competing and training, not being inside a room all day teaching class after class.
The first step to know what a teacher is made of, therefore, is a sincere self-analysis and the self-knowledge for the person to realize what they want for themselves. The flame of transmitting knowledge and the desire to change people's lives is inside each person, not elsewhere.
As Rickson Gracie teaches, "my goal today is to work for jiujitsu, restore our culture and serve a greater number of people, transmitting an accessible, enriching jiujitsu, which empowers people to solve problems with efficiency on and off the mat. I want to pass on the fundamentals so that anyone can learn to breathe under pressure, to have patience when necessary, to take an opportunity to finish in a tight manner, to use the body's leverage, to know the strength we have without the use of the musculature, the right timing of the positions... My mission is to make the technical details available for the beginners to learn to live and train with more balance, stronger, with more capacity of control under pressure."
In case you wish to be a master like that, there are basic ways to hone your didatics. If you are a purple- or brown-belt and are thinking about teaching in the future, offer to help your teacher in group classes. Offer your help for private lessons. Take part in seminars, as a student or assistant. All of this will slowly shape your didatics, as well as contributing to your technical quality.
At the end of the day, the competent teacher is the one who inspires, saves, and changes people. As Master Rickson says, "The weakest student in the school is the one that needs help the most, and the one that will yield the greatest reward when you manage to help him alter his life."
What is known today is that quality of teaching does not depend on big or small classes, or on whether a school is luxurious, elegant or well equipped. What matters, when it comes to learning, is the teacher's quality. That's why we see jiujitsu world champions shaped in such diverse places.
In the end, as teaches the writer Arnaldo Niskier, "good teachers define clear objectives, apply high standards of behavior and manage teaching time with wisdom."