The good teacher was, of course, Iroh, while the bad student was Azula.
Granted, Azula's talent for bending and her intelligence were both top-notch. She could pick up most moves on her first try and easily handle the vast majority of situations, but this also caused her to regard many things with a certain disdain. When it came to bending, she found it even harder to settle down and hone herself.
On the other hand, her pursuit of bending was not pure, either. She merely treated it as a means, a tool, and mostly sought no deeper understanding of its theories.
His values and understanding of the world, however, had already taken shape during his previous life as an ordinary person. After discovering that he had been fortunate enough to possess exceptional talent in this life, he treasured it all the more and knew to guard against arrogance and impatience.
Moreover, the world he had lived in before transmigrating had possessed no supernatural powers, which was why he had an unparalleled interest in bending.
It was precisely these two differences that had gradually widened the gap between Azula's strength and his in the later stages.
Back then, to prevent Azula from stumbling over these problems, he had also gone to painstaking lengths to chew up his insights before feeding them to her. Unfortunately, the results had ultimately been limited.
Compared to dry, boring bending theories that seemed to serve little purpose, Azula was clearly more interested in things like schemes and power struggles. He, on the other hand, had gained quite a bit more in the process of organizing and summarizing those theories.
That was also why he called Azula a bad student.
Back to the matter at hand.
Kahn's theory had won Aang's and Katara's approval, which meant Aang