Robert Soubeyran 's 20 Lessons Of Solfeggio Volume 1 is a collection of exercises that can be used to teach pitch and sight-singing. These 20 practice pieces will not only be of great help to teachers, but they will also afford pupils a systematic progressive and complete study. The study of clefs is often viewed as difficult and complex, however, by using this work, pupils can hope to make rapid progress, mastering this essential theory.