Part of learning and training to be an art teacher or rather, art educator, is to understand how to see, observe, and analyze art with a willingness to listen, return, and appreciate. Some say that maybe the underlying question is whether something is good art or not. But I personally think that there cannot be bad art, let alone label a work as good art. Then, wouldn't that be saying that one who labels a work as good art may also label another work as bad art?  What makes a certain piece of work bad? 

Perhaps one can say that a certain work works more successfully than another, but it is not to say that the work compared to the prior piece is not good art. They are all good art. As an aspiring art teacher, these would be situations where judgments must lay outside of the boundaries. 

I think that art is personal, functional, representational, expressional, and all of the above. The vagueness that lies beneath what art could actually mean is infinite and it challenges one to believe that this is why art can be anything the individual wants it to be. But to label art as good or bad may affect the chances of overseeing the kind of art that may speak to you, in an aesthetically pleasing or non-pleasing way. Let the experience in front of you guide you towards your own observations and conclusions.