Ok, so here's the thing: introducing Gerhard Richter and doing abstract paintings about color mixing using scrapers is easy. It fits into the elementary curriculum, and uses a contemporary artist as an example. Also, Wolf Kahn. Landscapes with alternative colors. Almost Fauve-ish. I use sculptors like Mark di Suvero and Richard Serra in a "monumental sculptures" lesson at 5th grade. I like to add Janet Fish for still lifes and Anselm Kiefer for using texture under paintings.
But what about Michele Oka Doner? Check her art out at: http://www.micheleokadoner.com/home.html. Her sculptures are very intriguing, but how do you use her in elementary school?
How do you use Tara Donovan? http://www.acegallery.net/artistmenu.php?Artist=8#
Also, German conceptual artist Mario Reis. http://www.fassbendergallery.com/Reis/index.html It would be fun to try to replicate his work in a nearby stream in a unit combining science and ecology. maybe I'll think about that one.