I'm going to be a literary analyst here, just for a moment.
The title on the cover of the book is for merely attracting kids. The real title of the book, actually, isn't explicitly mentioned anywhere in the book.
However, teachers of English literature can see through a poet's "the curtains were blue, why so I have not a clue", that the reason behind the curtains' being blue was actually the poet's sadness, though the poet himself never said so.
As you read this book, you see something similar. It screams in every page "You guys don't have the faintest idea how to teach maths", "math education done right", and so on. The real title, hence, I believe, is "A boring teacher's guide to the fun world of mathematics". Recommended for kids, yes. But much more recommended for those who teach kids.