a. Scales constructed with tetrachords combine two tetrachords and a link (abbreviated L). The link is always composed of two half steps (a whole step) on adjacent staff degrees. The link may be placed at the bottom, in the middle, or at the top of the scale. The combination of two tetrachords and a link form a scale that encompasses an octave (Figure 1-6).

b. The combination of two tetrachords and a link form a scale that encompasses an octave. An octave is an interval containing twelve half steps. It is the distance from one pitch to the next higher or lower pitch with the same letter name C-C (Figure 1-7).