Its not a sport deal with it
Its an activity because there is no ball involved. All sports have balls involved. Plus, its not considered a sport in school because in my high school you can only sign up for one sport each sport season and there are people who do dancing and a sport. Plus, the dance you are doing on stage is already planned, you know what is going to happen. In a real sport the chances are endless and you have no idea what to expect. That is why dancing is not a sport.