Rules for 7ths:
- The intervals that are white notes use only white piano keys. Those that are black notes use at least one black piano key.
- 7ths use six letters. (For example, C—A is C D E F G A B.) Their “size” depends on how many keys we skip.
- A diminished 7th skips eight keys. It is four whole steps + a half step.
- A minor 6th skips nine keys. It is five whole steps.
- A Major 6th skips 10 keys. It is five whole steps + a half step.
Note to more advanced students:
- Circle one shows the standard spelling for a C# fully diminished chord.
- Circle two shows the standard spelling for a C7 chord.
- Circle three shows the standard spelling for a Cmaj7 chord.