The Tale of Jemima Puddle-Duck by Beatrix Potter. 1908.

Natural science, dramatic irony, ageless value? Ducks sit on a nest for 28 days; the gentleman is really a fox; the puppies eat Jemima’s eggs at the end! Unlike, say, Little Bear, the illustrations move beyond the text and provide dramatic irony, which moves the plot along significantly. Poor dumb duck; she gains her life but loses her babies.

Standards for what's suitable for children have changed a lot (understatement of the year) since Puddle-Duck's day.