"I Was a Rat!" by Philip Pullman

Another Philip Pullman book, this time aimed at kids but just as entertaining as an adult as it would be for a child. Little Roger was turned into a boy, and despite his best efforts to integrate, the whole mad adult world is turned against him by their own ignorance and the gutter press. It's hilariously literal and doesn't condescend at all, and the whole concept of tabloid newspapers is explained entirely accurately for children in just a few very funny pages.

Any fluent child reader should be able to manage this on their own since most of the difficult words are easily deduced by their context, although many like "malevolent", "furtive" and "squalor" would be worth the effort of looking them up, and you're obviously not really expected to know what "anthropoid" means anyway.

I remember in third year that my primary school ran out of books that I would read, since their libraries were arranged according to reading level, and could only get a purple sticker if they consistently avoided big words but contained the requisite number of purple-level words. Someone must have had to count them. This resulted in shelf upon shelf of books with consistent vocabulary, rather than anything with a plot and a sense of humour which might have motivated any of us to pick them up in the first place.

"I Was a Rat" probably wouldn't get a purple sticker because "malevolent" almost certainly wasn't on the purple list, but even an "orange" reader would get enough of the plot to get hooked, and if it's too much work it'd be just as much fun for an adult as a child to read aloud, although make sure you're sitting close enough to see the illustrations.