All About 3rds

03-AllAbout3rds2

Rules for 3rds:
  1. The intervals that are white notes use only white piano keys. Those that are black notes use at least one black piano key.
  2. 3rds use three letters. Their “size” depends on how many keys we skip.
  3. A diminished 3rd skips one key. It is also a whole-step.
  4. A minor 3rd skips two keys. It is also a whole-step + a half-step.
  5. A Major 3rd skips three keys. It is also two whole-steps.
  6. An augmented 3rd skips four keys. It is also two whole-steps + a half step.
Note to more advanced students:
  1. Circle one shows a C Major chord moving to a C7 chord, which then resolves to an Em chord. The enharmonic spelling (Bb is changed to A#) is chosen to show that the C7 is a “German 6th chord” going to somewhere else other than a C Major chord.
  2. Circle two shows a C# fully diminished chord written with three minor 3rds, “stacked”.
  3. Circle three shows a Caug chord, written with two Major 3rds, “stacked”.
  4. Circle four shows a Gsus7 chord moving to a G7 chord, which then resolves to a Bm chord. The enharmonic spelling (F is changed to E#) is chosen to show that the G7 is a “German 6th chord” going to somewhere else other than a C Major chord.

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