I have a mix feelings on this book. I like the way it explain the «microbiology» of the human body, with all the organism in the intestine and all that. It was explain in a good way and easy enough for children to understand it and the illustrations, even if a bit fantastical, were good to make the book and subject attractive. My concern and question is : «Was it necessary?». This book is clearly intent for very young kids and I'm just not sure how relevant this is for children so young. I'm saying that in a general matter, if your kid want to learn about it, this is fine, go ahead and maybe this will grow on him and became a passion or a field of expertise or whatever, but not sure this book will reach a very large public. Nonetheless well done if you're interested!