This is a charming book on Art History for children (and everyone else). Each chapter focuses on a great painting, reproduced in color in the original text. The authors explain the story behind the paintings, as well as the life, times, and techniques of the artists.
You may find downloadable versions of all sixteen paintings at http://www.archive.org/details/Book_of_Art_Illustrations_lv, and you can easily do a google search for the other artworks mentioned in the book. (Summary by Kara)