Creativity needs to be encouraged. Younger students especially need to hear that their ability to put something on paper is not the important thing. Their abilities and their fine motor skills will develop over time. Their art technology will continue to advance from finger painting to crayon drawing to pencil to ink to paint all the way through sculpting, photography, computer art, video etc. Their ideas may be in computer graphics, but their technology may be in pencil.
Real art takes place in their imaginations.
A positive self image should be maintained. A good art project is a great self confidence builder. It is the teacher's job to find positive elements. Many people believe that teaching art to younger children is simply allowing them to copy a model picture. With this approach fine motor skills only are developed.