smART Kids is a site by the David and Alfred Smart Museum at the Univserity of Chicago. There are sections for kids, parents, and teachers. For the kids, they can choose to learn art vocabulary, be an art detective, learn to view art in different ways, and go to an artist's studio.
The Artist's Studio is sponsored by the Minneapolis Institute of the Arts. The toolkit is an interactive experience that teaches students about line, color, shape, balance, space and movement. In addition to short video tutorials, there are sections where kids can practice what they learned and create their own art.
Inside Art is like an interactive story about a person who "falls" into art and experiences it firsthand. It's similar to a choose-your-own-adventure story.
Art Express is sponsored by Harcourt Express and appears to have been created to correspond with an art textbook. There are different units to click on (see numbers in picture above) where the student and teacher can then choose a variety of different art concepts that are interactive. There is a lot to this site and is worth exploring.