To jog your memory, here was the question...
Question: how can we make the chord progression below easier to play?
Gmin - C - Gmin - C - F
Answer: By using a capo at the 3rd fret, your new progression will be:
Emin - A - Emin - A - D
How we figured it out: By putting a capo on the 1st fret of the guitar, all our chords dropped by a half-step (F♯min - B - F♯min - B - E). Perhaps a little easier, but not really. So, we moved the capo up to the second fret, and dropped the chords another half-step (Fmin - B♭ - Fmin - B♭ - E♭). Nope. So, we moved the capo up to the third fret, and BINGO! (Emin - A - Emin - A - D)
Ideally, over time, you'll learn to do these calculations in your head, very quickly. Chances are, this first calculation took you a while. Keep trying, and you'll get faster in no time.
