Some of this repetativeness / lack of perceived growth is developmental.
I've had kids that just couldn't "see" the forms I thought were simple
because they weren't developmentally ready to see them. I agree that kids
need to push themselves -- I've been frustrated too with a few of my 6th
grade students who STILL put the sky on the top of a page and the sun in the
corner. Even after looking out the window in search of the corner-sun circle
and recognizing that the sun is a great big light source that doesn't really
appear like a ball. They look out the window, make their observations, then
draw the same thing they drew before. When asked about it, they say "But I
LIKE it this way!" Sometimes I just have to let go and let them be kids,
happy kids making pictures and art that makes them happy. Even if it doesn't
always make me happy!!
Amy R.