If your choir can sing up and down the scale, they're ready to dive into this series! Each volume of this flexible series contains 150 duet (or 300 unison)exercises that progress sequentially from completely step-wise and diatonic melodies to more difficult intervallic leaps and rhythms in virtually all keys. The Two-Part edition volumes are available in two different versions: SA (all treble clef) or Two-Part Mixed or TB (treble clef and bass clef). This series can also be used by solo singers or by choir members on an individual basis and all five volumes are fully compatible with the parallel unison, three- or four- part versions. Fully reproducible, and available as a digital download, this comprehensive series provides an exhaustive library of sight-singing material that is useful year after year.