Try playing a G chord followed by the E minor.
Can you hear how similar they are? If we look at the notes that make up the chord, we see the following:
| I | III | V | |
|---|---|---|---|
| G | G | B | D |
| Em | E | G | B |
Notice that these chords share two of their three notes. This is because E minor is the RELATIVE MINOR of G major. The relative minor shares the same notes in the major scale, but it's root is the sixth of the major. Here's our G major scale:
| I | II | III | IV | V | VI | VII | VII |
|---|---|---|---|---|---|---|---|
| do | re | mi | fa | sol | la | te | do |
| G | A | B | C | D | E | F# | G |
In order to find the relative minor we look for the sixth and make that the root. Therefore, E minor is the relative minor of G major and the E minor scale would look like this:
| I | II | III | IV | V | VI | VII | VII |
|---|---|---|---|---|---|---|---|
| do | re | mi | fa | sol | la | te | do |
| E | F# | G | A | B | C | D(#) | E |
Here's a chart of a few major/relative minor keys you can use (but please feel free to make out one of your own, listing all twelve possibilities as a test!):
| MAJOR | RELATIVE MINOR |
|---|---|
| C | Am |
| D | Bm |
| E | C#m |
| F | Dm |
| G | Em |
| A | F#m |
| Bb | Gm |