I bought some rocks at my local Michaels store to paint and create a game with. i am sure that will come soon. Meanwhile, we took them out of a cold day and lined them up. I, of course, had to help in this but a great way to teach Henry about graduation of size.
I adore Kid-O toys. This is Matching Shades. "
Encourages children to recognize gradated colors and to distinguish subtle differences by matching circle to appropriate color shade." This wasn't too much of a challenge to Henry but it is was a way to teach him "lighter and darker".