I have found several inconsistences in this textbook. In most chapters the model is not introduced until "after" the first problem is worked through, not ensuring that there is any understanding of the model. I've noticed a lack of strict adherence to the model, and because of that there are few reinforcements of a students basic understanding. There are assumptions that the student is not at all confused or weak on any of the basics, and that leads to further confusion. Although the textbook is supposed to be setting a foundation for continued math learning, it does more to confuse the student than enlighten. For the money spent, new or used, this textbook is far from being a useful tool.