I admit I was convinced by the beginning of the book on agreements of past participles, just under the last part on dangerous subjects. Overall, the book reads like a storybook or adventures, but young children (mine between CE1) need the support of parents to understand and implement the methods of the book. I recommend to help children open learning to acquire "automatic" spelling and grammar, but also to adults (always happens that one wonders about the agreement of a past participle) that will troubleshoot well.