Music Theory

Lesson 7


Key Signatures and the Circle of Fifths


In the previous lesson we learned about the construction of the major scale, which follows the formula WWHWWWH.  Using this formula to apply the correct number of accidentals for a given scale is relatively simple.  Yet wouldn't it be nice to be able to construct a scale simply by notating the eight scale degrees and not have to worry about the whole step-half step formula?  This is possible by using a key signature, or a set of accidentals associated with each of the major scales. Key signatures are placed just after the clef sign at the beginning of each line of music.  This placement saves a lot of time and space, since every note that would need an accidental is taken care at the beginning of the staff, and you do not need to reapply them.


Sharps and flats are not randomly chosen in key signatures.  In fact, sharps and flats never appear together in key signatures.  There is a specific order for the placement of each of these accidentals.  The order for sharps is F C G D A E B, or Fat Cats Go Down Alleys Eating Birds.  The order of flats is the reverse of this, or B E A D G C F.  Therefore, any time you have three sharps in a key signature, they will always be F, C, & G.  If there are five flats in the key signature, they will always be B, E, A, D, & G.  Finally, when you write a key signature, whether you use one accidental or all seven, they must be placed in these positions:


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© Copyright 2005

Mark McFarland