This is a great place to start with kindergarten. Our first project this year was an exploration of the color wheel, the primary colors, and abstract art created by mixing them together. The piece they created was then titled and imagined in a large frame as they posed before green screen pretending to gaze at it...pondering, "what is art?" I made a tutorial of how to put this lesson together in keynote. View it here.
I created an interactive color wheel game and coloring sheet so students could explore color mixing before we used paint. View this resource here.
One of the books I like to use to introduce kindergarteners to the variety of forms that art can be is ART IS... by Bob Raczka. I made a movie of my reading of the book with images and text to help the students see the book easily in art class. View it below or at this link.