I'm not sure where to start with this book. My first reaction was that it was really not about calculus nor was it for babies. After a first read, I put it in the "donate to library" stack downstairs in our home rather than showing it to our baby. Then the baby, my granddaughter, saw it in the stack, amongst other books, and grabbed it and started gurgling whatever it is 6-month-old babies gurgle about. This is now her go-to book in her toy box. So, she gives it a 5 while I would give it a 1. But, who is this book for? Not me! It's for babies, so she wins, but I'd like my vote of 1 star to count for something when calculating the mean, so I gave her vote of 5 stars a weight of 1.4, making the total stars 4. When she learns to speak properly rather than in baby gurgles, then we can have a discussion about whether this is fair. One last thing in this rambling and boring review, I've found that so many baby books are full of words (surprise!) and not a lot of numbers. If you've used phonetics to teach your toddler to read (see larrysanger.org/2010/12/baby-reading ), then you might come to the same conclusion as me, namely, reading is a lot more complicated than mathematics. We seem to intuitively know that, so we expose our kids to pages and pages of words and pretty much leave the math to take care of itself, only to have our children enter school to learn that math is too hard. My son was a bit of a maths wiz, being promoted to university mathematics classes in high school, and now that he is in his thirties he tells me: "In grammar school, those teachers couldn't even factor simple exponential binomials, leaving myself and other students wondering what was wrong with them. Instead of learning the process, they would spend class time telling us how hard math was." What my son didn't know was that we would throw in a book full of numbers along with his other books which were full of letters/words so that he could start at an early age to see how easy it was to manipulate equations. So, no matter how much I don't like this "Introductory Calculus for Babies", it appeals to my granddaughter and introduces her to mathematics concepts and she sees a book which doesn't just have letters in it. By the way, one book the both of us like is "The Pythagorean Theorem for Babies", by Carlson. If you can find the time, please have a look and compare it to "Introductory Calculus for Babies" and see what you think. Finally, one last book which she just can't put down is "123", by Jo Ryan, Sarah Powell, and Amy Oliver. It is a great introduction to counting for babies, probably because it has texture and they like to run their fingers over the items to enumerate (at least that's true for our granddaughter). Happy counting!