You’ll be pleased to know that all the chords we’ve learned so far form the key of C Major, which is an incredible useful key to know. If you play them in order, C – Dm – Em – F – G – Am – B° – C, you should hear the familiar do-re-mi sound.
This is a good way to learn theory as it’s essentially giving a name to a sound, or in this case a series of chords, that you already know.
This information is very powerful because we can start to combine different chords from the key into chord progressions, but before we do that we’re going to assign each chord a Roman numeral.
C – I
Dm – ii
Em – iii
F – IV
G – V
Am – vi
B° – vii°
As you’ll notice, upper case is for major chords and lower case is for minor chords and the diminished one. This system is used by musicians to communicate as the information is universal in all 12 keys; for example, the I, IV, V chords in any key will always be major, the ii, iii, vi chords will always be minor and the vii° chord will always be diminished – only the note names change.
As there are only 7 chords in the key, there are a number of standard chord progressions used in millions of songs. I’ll give you the Roman numerals so you can try them out:
I – V
I – IV – V
I – IV – I – V
I – vi – IV – V
I – V – vi – IV
vi – IV – I – V
Practice changing between the chords and really listen to what you’re playing. You don’t have to do any complicated strumming if you’re not ready as we’ll tackle this in the next section.
Checkpoint: You should now know the chords in the key of C Major and be able to change between them fairly cleanly with each note of the chord ringing out.