I've always been a visual learner: If a book doesn't have illustrations, I always think, "This would be better if it had some pictures." If there are some black and white images, I think that they should be in color (and when I was little, I would turn my storybooks into coloring books, much to my Mom's dismay). I love color and lots of pictures. And this is especially true when it comes to art! I see no point in art books printed in black and white! Van Gogh painted in vivid color--you really can't understand his work without it. Georgia O'Keefe's work just isn't the same in shades of gray. For many art movements, color was the whole point!
My point is, kids can't learn about art just by talking about it--they need some visuals. And one of my favorite publishers ever since I was little is DK Eyewitness Books. Their publications are a visual learner's paradise. DK's Eyewitness art books remain some of my favorite resources to this day. Their books are smart, informative and visually engaging. They understand that kids don't have to be talked down to when learning something new. They give you a word, define it and show you a picture of it, which helps you remember it far longer than merely seeing words on a page. Kids and adults can read the same book and get something out of it. There are books on art history, artists (multiple books on some of the more famous ones), and how-to manuals for different art techniques. Look them up at your library and you're sure to find at least one book that pertains to a topic you're currently covering.