Some kids will never be able to solve very very difficult...
At school pieces of art work shouldn't be graded/levelled
There is a reason why some artists are very famous and a lot of money would be paid for their art work, and other people's art isn't as popular/famous. In school, when a kid is not as good as another kid at math, sometimes no matter how hard they try, they will never be as good. Some kids will never be able to solve very very difficult mathematical problems, and some kids will never be incredibly artists. Those subjects both are graded in school, because that is a way to allow you to know which one is better than the other. Saying all art pieces are just as good, is undermining the subject of art. My drawings will never be as good as Piccaso's or Dali's. Art is harder to measure, just like it's harder in a history test to say if the answer you gave should be graded 80 or 90, and in math it's rather straightforward -how- you grade it. That doesn't mean that there is no one that is better than the other in art, it just means you need to think harder to know how to grade it. Usually, school standards allow you, even if you are very bad at something, to hold decent scores, because it's fit for the average kid and not for the brilliant one in each subject. In that way it doesn't majorly harm you if you are not amazing in arts, or for that matter if you struggle in history/math.