ABSTRACT
A pentatonic scale has five scale degrees. The most common pentatonic scale can be thought of as a subset of the diatonic collection. There are seven diatonic modes for every key signature, and there are two ways of modeling the modes. The first way, which is historically accurate, is to list the modes in ascending order along the notes of a given diatonic collection. The second way of organizing the diatonic modes is to maintain a consistent tonic and alter the key signature. Notice also that these scales are arranged so that their implied key signatures are in circle-of-fifths order, resulting in a smooth progression from one sharp to five flats, all while maintaining C as the tonic. This collection is sometimes referred to as the major pentatonic scale, although because it is so very common it is often simply called the pentatonic scale.
