We got a book recently called Not a Box, and in it, a rabbit is playing with what looks like a box, but is really one of any of a number of imaginary creations. In one of the later pages, the rabbit is thinking of what it is he’s playing with if it’s not a box.
I found Agnes and Miranda saying “Hmm” as they were looking at that page.
[If you can’t see the Flash player above, you can download the video in XviD format: XviD (1MB).]
Eleanor has started saying this spontaneously when she’s working on something. Today, she was doing it while working on a jigsaw puzzle.