Hey Friend,
I was looking over some notes yesterday and saw that I forgot something I wanted to share with you about each chord we study. As we look at the chords in a key, there's always another side of the chord we don't think about.
I'm not talking about anything covert, devious, or villainous, like Dr. Jekyll versus Mr Hyde. I'm talking about other keys that chord is a part of. Not the house keys, or the car keys. Those other keys... you know, musical keys.
The C major triad doesn't just show up in the key of C major. It can be found in the keys of G major and F major as the IV and V chords, respectively. It is also found in the key of A minor, D minor and E minor.
Here are the key charts showing the C major chords:
Key I IIm IIIm IV V VIm VII° C C Dm Em F G Am B° G G Am Bm C D Em F#°
F F Gm Am Bb C Dm E°
And the minor keys:
Key Im II° III IVm Vm VI VII Am Am B° C Dm Em F G Dm Dm E° F Gm Am Bb C Em Em F#° G Am Bm C D
Speaking of D minor, here are the keys it can be found in...
Obviously, the key of C major - because we talked about that all last week. And the key of D minor - because it would be the 1 chord.. Okay, maybe not obviously, yet. But you'll get the hang of it pretty quickly. How can I be so sure. Because it's just another pattern.
It can be also be found in the keys of A minor and G minor. For the major keys, Bb (B flat) and F major are the other two.
Key I IIm IIIm IV V VIm VII° C C Dm Em F G Am B° F F Gm Am Bb C Dm E° Bb Bb Cm Dm E F Gm A°
Key Im II° III IVm Vm VI VII Dm Dm E° F Gm Am Bb C Gm Gm A° Bb Cm Dm Eb F Am Am B° C Dm Em F G
Lots of information there, and you might scratching your head thinking "Why did he just throw all that stuff at me?" Well kiddies, here's why.
As you can see from the above charts, when you learn a new chord, you're not just learning it for one key. It will show up in five other key signatures! And you're like, "So what!"
Here's why "so what." You can use the particular chord as a "pivot" chord, allowing you the change the key (modulate) of the song on the fly! It's actually fairly straight forward, but we don't often think about things outside the current context, especially if it's never been pointed out to us.
Good song writers change keys in a song all the time. That way, they can write songs that are interesting and unique. The crazy part of it, though, is that they might only change the key for a measure or two before either changing it again or switching back to the original key. So that's something we have to watch out for. Here's an article that highlights a few examples of key changes in songs. This is by no means an exhaustive list...
Alright, see y'all tomorrow. Have a great one!
Peace~
Dave | 
