It's useful to spend some time on individual tones/intervals and how they interact with chords. Some intervals, like this one, have a rather special function. In this lesson (an excerpt from my Chord Connections course ), we look specifically at the 4th (long name, perfect fourth ) over major chords. The 4th is typically considered a "passing tone" over major (e.g. a major triad or maj7). It funct...