Children's books aren't textbooks. Their primary purpose isn't supposed to be "Pick this up and it will teach you this." It's not how literature should be. You probably do learn something from every book you pick up, but it might be simply how to laugh.
J. K. RowlingThat old berk," muttered Aberforth, taking another swig of mead. "Thought the sun shone out of my brother's every orifice, he did.
J. K. RowlingDo you mean ter tell me," he growled at the Dursleys, "that this boyโthis boy!โknows nothin' abou'โabout ANYTHING?" Harry thought this was going a bit far. He had been to school, after all, and his marks weren't bad. I know some things," he said. "I can, you know, do math and stuff.
J. K. RowlingOh, come off it,โ said Ron, striding over to her and whipping her results out of her hand. โYepโ ten โOutstandingsโ and one โExceeds Expectationsโ at Defense Against the Dark Arts.โ He looked down at her, half-amused, half-exasperated. โYouโre actually disappointed, arenโt you?
J. K. Rowling