I was sure SOMEONE would comment about my previous Key Signature post regarding the ‘exception’ to these rules! You were all too nice to me, or else you recognized my trap and steered clear!
Although the shortcuts I outlined are correct, they can signify either the MAJOR key (i.e. C) or its Relative MINOR (i.e. Am). The Relative Minor is 3 half-steps below the Major. C=Am as they both have no sharps or flats. The Relative Minor of G is Em, as they both have one sharp (F#). The Relative Minor of F is Dm, displaying one flat (Bb).
Keeping in mind that a Bb noted at the beginning of the piece can signify either the key of F or Dm, the easiest way to determine the key of the piece is to play a few bars to determine if it is major or minor in its sound. Often, you can also look at the last measure of the piece (if it contains no modulations/key changes) as a piece will usually end on the root or tonic of the key.
This may seem a bit complicated, but it really isn’t. Just pay attention to the Major keys first, as you will likely study them first in your theory lessons anyway. Then, if the piece sounds minor as you play through it, you automatically know it is in the relative minor key, three half steps down.
