The "Belwin String Builder" is a string class method in which the Violin, Viola, Cello and Bass play together throughout. Each book, however, is a complete unit and may be used separately for class or individual instruction. In this method, the quarter note approach is adopted not only because it is the unit of the beat, but because it encourages freedom of the bow arm at the outset. The material in this book is realistically graded, and each melody is interesting.