"L'altalena" by Enzo Mari (first printed in 1961) can be a book, but also a game or just a entertaining strip to hang up. The single strip with concertina-folds is full of animals, that leap with their bodies onto the swing trying to keep the balance. The book contains no words, but speaks conceptually of quantity, shape, weight and balance. I think, it's still very modern.
See also: Valesulfilo
