This math book teaches Integers, a topic that is completely neglected in school except some mention of “there are positive and negative numbers” and then discussion of the rules in operations with integers.
Fact 1: Many kids see their grades drop when they start studying Algebra.
Fact 2: Many kids see their grades drop, or drop more for some, when they start studying Calculus.
Fact 3: Those are not bad students but many are 'A' students.
The common explanation: Algebra and Calculus are conceptually hard (nonsense), and most students are just not naturally inclined to math. Sometimes the explanation is that "the student is not working hard enough." Not true in many cases.
The real explanation: Algebra and Calculus require understanding of numbers, operations, and our place value system. Not in a superficial and operational, can only use but doesn't understand, way. They require a deeper level of understanding. They require students to really understand numbers, what they represent, and how they work.
That's where Integers come into the picture.
Integers are a very important concept. They are not just "negative and positive numbers". An integer is a new idea compared to whole (positive) number (it's an idea about direction).
Fact 4: Schools and math books DO NOT TEACH Integers! None does. Students are told (or read) that “integers are just both positive and negative numbers”. They they learn the Rules (e.g. “negative times negative is positive"), which don’t really make sense to the poor students who were not taught what integers really are. Naturally, they forget those rules quickly.
Then comes Algebra, with its extensive need for understanding Integers. Without understanding the idea of Integers, how they work, and how to use them, students have no chance in understanding Algebra well, and of solving Word Problems (see the book on those) that require those ideas. Later, when students study calculus, which introduces real numbers, it is even more critical to understand Integers fully and deeply.
This book teaches EVERYTHING to know about Integers. It does so simply. It explains what Integers are; the meaning of operations with integers; and how to use integers. Those “negative times negative is positive” rules become logical and easy to remember because students understand why they are so. Then, when they learn Algebra and Calculus, they are not confused, and they often do better (you do want them to use the Word Problems book before Algebra).
Get the book and make your kids' experience with math a positive one!