Otoshi, Kathryn (2008)  One.  (PreS-K)

"Red is hot, and Blue is not."  Blue is quiet and gentle, even when taunted by a bully.  But Red's meanness leaves Blue feeling blue.  Yellow, Orange, Green, and Purple try to tell Blue that blue is cool ... but no one stands up for Blue when Red is around.  Red bullies and sneers and makes the other colors feel small and unimportant.  No one wants to go against Red.  Not until One shows up.  With One's help, all the colors start to stand up for themselves and for each other--and they learn that everybody counts.

The simple shapes and lines of this book introduce both colors and numbers as characters--maybe even as friends.  The delicate watercolor textures lend themselves to close, quiet readings between a parent and child, but the simplicity and scale of the illustrations would also work well for smaller group read-alouds.