Blue Sea by Robert Kalan (1979)

One of the best books for getting kids involved in telling the story (dialogic reading).  With so few words, kids can jump in and describe what's happening on the page ("what do think is happening?").  And the pattern is so strong they also anticipate the next page ("what do you think is going to happen next?"), which is great for building narrative skills .  It works great in a group, but it's also a book that a non-reading child can pick up and tell on their own just going from the pictures.  

Even though it doesn't have many words, this is also great for vocabulary :  Introduces comparative ("bigger, smaller") and superlative ("biggest, smallest") adjectives  in a way that kids really get.   

- Steven Engelfried