Simply put, Guess Again! is a trip! Rhymes lead you to guess the identity of the figures on the page. You won't guess correctly, but that is why this terrific piece of absurdity is so much fun. Author Mac Barnett and illustrator Adam Rex have created a great vehicle for teaching prediction and drawing conclusions. As others have mentioned, my only complaint is that there are not more opportunities to guess. Mac and Adam, we need and demand a sequel!
Throw this changeup when you are teaching about prediction or drawing conclusions. Read it in the middle of a unit and see what happens. Reading Guess Again! could also lead to students creating their own Guess Again! books. It would be a fun twist on teaching phonemic awareness.