Ms Art Teacher had an interesting post last weekend. I thought I'd pass it on for you to read while I'm away.Ms. Art Teacher blog.
Let me know how you grade.
Personally I don't like to grade but it is a necessary evil. We have a 3-2-1 system. 3- On grade level, 2- Approaches grade level, 1- Below grade level. I grade a lot on craftsmanship, remembering that some kids develop at different times. Then I consider the main lesson, pattern, use of color or what ever skill I am teaching.