In sight-singing classes at colleges and universities in the United States, there are various solmization methods in use, such as movable do, scale-degree numbers, and fixed do. Few sight-singing textbooks and other related books are willing to stake a claim of preference for one method over the other. Since many textbooks and other books are unwilling to take a pedagogical stance on a solmization system, instructors need to research each book in order to determine the biases in the book and how well it works for their classes. To aid them in that endeavor, this dissertation determines the biases in textbooks and reveals which textbooks work well for which systems. The dissertation begins with short descriptions of solmization systems as gathered from articles, textbooks, and other aural-skills related books along with a review of the literature. Then, it discusses elements of music to evaluate, reveals which elements receive an evaluation in the textbooks, and indicates why some were not chosen. From here, the dissertation lays out the expectations for each category evaluated using support from aural-skills related books and articles. After laying out the expectations, the dissertation describes the approaches of each textbook in select categories, reveals biases in the textbooks, and identifies textbooks that align more closely to movable pedagogical methods and others that align more closely to fixed pedagogical methods. The results of this dissertation reveal that most books use pedagogical methods of multiple solmization systems, but still have a bias for predominantly one method. About 64 percent of the textbooks (14 books) use more movable system approaches, whereas approximately 36 percent (8 books) use more fixed system approaches. When twentieth-century idioms occur, most of the books use fixed approaches for that material.