One of the things I really like about the Kung Fu Panda series is just how well it illustrates that different people have different learning styles and need different teaching styles. Once Shifu decided to stop being a butt, he modified his teaching style to match Po’s learning style, which is the mark of a great teacher. Once Po was taught in the style that matched his learning style, he excelled and became the best kung fu warrior: the dragon warrior.
On a related note, Po seems to have ADHD. People with ADHD usually get left behind because the teacher isn't willing to work with their differences. Instead of utilizing their strengths like Shifu did (Po's focus on food), they instead try to punish them for their deficits. Shifu started out doing this but changed tactics when he decided to seriously train Po.
And, this wasn't something just from the first movie. It was there again in the third movie when they had to teach the panda village how to fight.