What Key is it in?

How do you figure out what key you are playing (or singing) in?

Often a piece will begin or end on the tonic, or the “home” note of a scale. A scale is an arrangement of pitches, or notes, that a piece of music is based upon. A quick way to tell what key the music is in is to look at the last note of the song, in the bass line of the accompaniment. This is not a hard and fast rule, but generally speaking, most music ends on the tonic, or the first note of the scale. 

Another way to tell what key a song is in is by looking at the key signature, or the arrangement of sharps or flats at the beginning of a piece. For sharp keys, you look at the placement of the last sharp and go up one lettername. So, if you have a key signature of two sharps and the last sharp is C#, you know you are in the key of D. You can double-check this by looking at the last bass note of the piece. 

For flat keys, it is even easier. You look at the second-to-last flat, and that is the name of the key. So, if you have a Bb and an Eb, you are in the key of Bb. The exception to this is the key of F, which only has one flat in it (Bb).

Flats and sharps are always listed in the same order. It is worthwhile to memorize their order to quickly determine what key you are in. Flats are arranged as Bb-Eb-Ab-Db-Gb-Cb-Fb ("Bead" + GCF). Sharps go in the opposite direction: F#-C#-G#-D#-A#-E#-B# (you can use the mnemonic Fat Cat Garfield Doesn't Always Eat Bananas).

All of these rules assume your music is in a major key. For minor keys you use the same rules, but then you must go backwards 3 letter names. So, if you have an F#, your major key would be G (go to the last sharp - F# - and go up one lettername). Your minor key would be 3 letternames down (G-F-E): E minor. You can check this by looking at the last bass note and by listening to how the piece sounds. 

Why does it matter whether you know what key a piece of music is in? Think of it like driving in a new city: the more information you have about where things are, the more quickly you can orient yourself to your new surroundings and figure out where you are going next.

Reading music easily at first glance comes about by recognizing patterns quickly and making educated guesses about what is coming next. It is similar to reading: our brain learns phonics patterns like ea, oa, tch, and so forth, so that when we read the words beach, boat, and catch, we quickly “chunk” the phonics patterns to read the words. Readers who only sound each letter out individually have a harder, slower time of reading because they haven't learned to identify familiar patterns quickly. Their reading will be labored until they put to memory the common phonics combinations. In music, key signatures and scales are two basic tools that must be mastered in order to develop musical fluency.

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