teaching piano to children is that most of the students which I have taught were gifted.
One of my first student was a child who engaged in bullying some of the other children with her friends. However, once she started learning how to play the piano, she stopped bullying, ended her activities with the friends, and became impassioned with learning new songs. She spent more time than most of the students, and as a result, learned more songs.
Another child was a problem child in classrooms in that he was disruptive. He had a friend who was the same way and the two of them together were difficult to manage. Since they did practically everything together, the two of them enrolled in piano lessons after school. The first student became very serious about playing piano and became disciplined, while the other just continued to be a disruption in the class, eventually dropping out because he had no interest in playing piano.
Children who develop their talents are happier than those who do not. While some of the other children who did not take an interest in piano may have been gifted in other areas, piano would not have been the medium for them to pursue. Some of the children who enrolled in the class were noticeably unhappy. One child related that it was not his decision to enroll in the class.
Therefore, if children are not doing well with music classes, it could be that this is not their area where they exhibit talent. I am in the process of writing a book which will explore this issue more in depth.