Book excerpt: Josh is the best collector on the block. And now he has something new to collect - rocks! Soon Josh and his best friend, Amy, have so many rocks they need to organize their collection. But how? Young collectors will be fascinated by all there is to know about rocks and about classifying - sorting and organizing objects by attributes like color, shape, or size. Grab your rock hammer and join the fun with this entertaining story by Stuart J. Murphy and lively art by Cat Bowman Smith.