I am jealous.
Even as a kid, I would have wanted to save the book for something really good. I would be afraid to mess it up. I would have wanted to practice on some other paper and then carefully, in my best handwriting, copy over the results into the book. There is no need for that.
The story had every essential element. There was an engaging protagonist with a specific problem, an exciting conflict, and a surprising solution to the problem. If a person of seven can grasp this, why do I struggle so much?