Learning Music Theory Part 8 (Key Signatures)

What are key signatures in music?  According to my absorption on this topic as I’m trying to learn music theory, key signatures help musicians to remove the clutter of accidentals in a music sheet when writing music notes.  Furthermore, knowing how to read key signatures helps musicians reading the accidentals on the music sheets that use key signatures.  So, instead of writing in every sharp and flat there is into a music sheet, a musician can use key signatures to tell other musicians to read his music sheet’s accidentals through key signatures.

By knowing key signatures on a piece, one will also know the scale type which one should play when reading a music sheet that uses key signatures.  For an example, let’s assume you know or remember all about G major scale, and by knowing G major scale by heart you know that this scale only has one sharp in it.  Furthermore, let’s assume you also know this G major scale has only one F sharp (accidental) in the whole scale.  So, by knowing these info, whenever you see a starting of a staff that uses key signature pattern of only one F sharp, right away you should know that you are playing a G major scale section.  Some musical sheets of whatever musical piece may change key signatures and scales throughout the whole musical piece.  Thus, one needs to be careful in reading key signatures in order for one to know when to play what accidentals of which scale at a specific section of a musical piece.

Key signatures fit nicely between the Clef and the Time Signature.  For an example, a Treble Clef would be written first, then the Key Signatures, then the Time Signature on a music staff.  There are rules to keep the using and reading of key signatures bearable and understandable:

  1. First rule, key signatures of a pattern of sharps or flats will always be in the same order.  OK, you probably scratch your head already.  No sweat, and here is the explanation.  Follow this simple exercise and you shall know the answer.  Take a look at the piano’s keyboard layout (get a piano’s keyboard layout through the Internet), you need to count how many sharps there are in the whole G major scale starting from the G musical note.  If you are doing it right, you see that there are only 7 sharps.  If you count backward from the last G musical note to the first G musical note (i.e., GFEDCBAG), you should see there will always be only 7 flats for G major scale.  Guess what, there will always be 7 sharps and flats for all scales.  How come?  It’s all because we use the half step rule.  As we all know, whenever we do a half step down, we are lowering the pitch by half step to create a flat.  Same thing goes for sharp, we make a sharp whenever we raise a pitch half step up.  Although a specific scale, except the C major scale, would have different accidentals in specific key places, the half step rule would always be successfully turned any key within a specific scale into a flat or sharp.  Since now we know that there are always be 7 flats or sharps in all scales, we can safely assume the order of these flats and sharps can never change, because these flats and sharps in any scale don’t have feet to move around the piano’s keyboard.  Thus, the first rule — which states the order of the pattern of sharp or staff will always be the same — is sound.
  2. Second rule, you cannot mix the flat and the sharp key signatures together in a key signature pattern for a section of a staff.
  3. Third rule, key signatures of a pattern of flats will always be in this order [BEADGCF].  If we reverse the flat key signature pattern, we form the sharp key signature pattern which is [FCGDAEB].  Same thing as the flat key signature pattern, the order of the key signatures in the sharp key signature pattern cannot be out of order.  You probably scratch your head already and ask why there are patterns for key signatures, right?  I scratched my head too, and I tried to find the answer to this scratching head curiosity.  Nonetheless, I found none, but then I thought to myself, perhaps the telling is in how many flats or sharps each scale has and how these key sharps and flats are fitting nicely onto a staff in specific orders for key signatures of sharps and flats.  Still scratching your head?  Let’s do this simple exercise and we shall see the answer:
    1. Take out a blank sheet of paper and draw a five line musical staff.
    2. Create a Treble Clef (ignoring time signature symbols as we don’t need them in this exercise).  We will draw in the key signatures in the staff later.
    3. On the very top of the blank sheep of paper you need to write out the key signatures’ sharps and flat patterns (i.e., BEADGCF for flat key signatures and FCGDAEB for sharp key signatures).
    4. If we play the G major scale on a piano’s keyboard layout, we know that there is only one F sharp as our accidental.  Draw the #F (F sharp) onto the five line Treble Clef staff which we had drawn out onto our blank sheet of paper earlier.  The #F sharp should overlay the 5th line of the five line staff, right?  If you remember your music theory correctly about the staff, the 5th line is the very top line of the five line staff since we’re counting the lines and spaces from the bottom up.
    5. Next, we need to play the D major scale pattern out on the piano’s keyboard layout, and by playing out this pattern we know that there are 2 sharps in D major scale.  These sharps are #F and #C.  Instead of repeating the drawing of #F sharp onto our five line Treble Clef staff, we ignore the #F and draw down the #C onto our five line staff.  The position of the #C should be above the 3rd line of our five line staff, and so this means that our #C is sitting in a space which sits between the third line and fourth line of the staff.
    6. Next, we need to play the A major scale pattern out on the piano’s keyboard layout, and by playing out this pattern we know that there are 3 sharps in A major scale.  According to our FCGDAEB for sharp key signatures, we know the 3 sharps are #F, #C, and #G.  According to how we play out the A major scale on our piano’s keyboard layout, we confirm that the sharps are #F, #C, and #G, but of course when we play these sharps out in A major scale in the piano’s keyboard layout, these sharps are not going from left to right or vice versa in order.  Nonetheless, if we draw out these sharps in our five line Treble Clef musical staff, we know that we don’t have to repeat the drawing of the #F and #C, because we’d drawn them earlier.  The only sharp for the A major scale that we need to draw onto our five line staff is the #G.  You should draw your #G in the space above the 5th line of the five line staff.

We can go on with the exercise of the rule #3, but it would be tedious.  By going through the exercise that I created for rule #3 earlier, we now see the pattern of why the key signatures for sharps are always in the order of FCGDAEB.  Thus, if we had completely done the whole exercise through and through, we should be able to reverse the order for sharp key signature pattern into flat key signatures pattern.  Anyway, check out the orders of flat and sharp key signatures on Treble Clef staves right after the break.


I don’t know if I’d missed any rule in regarding to key signatures or not, but the 3 rules I listed should help you a lot in knowing how to identify key signatures.  So, the next time we read a music sheet that got sections rig with key signatures, we know that whenever a music note — that is not being labeled with accidental symbol but matched a key signature — is an accidental instead.  For an example, if we see #F (F sharp) key signature, we know we have to play #F no matter what even if we see a music note is F natural in a section of a music sheet.

I know it’s hard to remember the patterns of key signatures for sharps and flats, thus mnemonic trick should be used to help you remember how to recall these key signature patterns.  For me, I only need to remember the flat key signature pattern, because it’s easy for me to remember the flat key signature pattern and then reverse the flat key signature pattern into the sharp key signature pattern.  Flat key signature pattern is [BEADGCF], and my mnemonic for it is BEAD Greatest Common Factor.  Nonetheless, you should come up with your own mnemonic for the flat key signature pattern so it will stick in your own memory better.

In the next music theory blog post, I’ll touch on the Circle of Fifths, because this is one of the formulaic methods of helping us easily to correlate the key signatures to a scale.  Basically, if one knows how to use the Circle of Fifths, one should be able to see what keys are being sharpened and flattened in which scale in seconds.  Thus, Circle of Fifths will help us name the scales such as G major scale when seeing the key signatures in place, quickly and easily!

In summary, knowing key signatures helps a musician to read and play accidentals on a music sheet that does not spell out each individual accidental.  Furthermore, knowing the key signatures’ position and pattern and the number of key signatures in place helps a musician to know which scale he is playing in.  Knowing which scale is important as it helps a musician not to lose his place on a music instrument.