Not a box

Ben and I read several books today - one being Antoinette Portis' "Not a Box"

This book is a simple illustration and text - and encourages what the imagination can do. The bunny has a box - but proclaims it's not a box - it's a..... hot air balloon, mountain, rocket...
So after reading it Ben asks "mom what's this?" -- and I say "Not a box" and he says "No, it's a rectangle."

Hmmph!