This post is one of a 2-part series of free basic music theory lessons on my blog, musictheoryde-mystified.com. You can see the complete list here. Please feel welcome to make a comment or ask a question.
This post and the next two cover two important musical concepts. If you need to read them more than once, please do so. If you have any questions, please post them as a comment. I’ll be happy to answer them.
Scales And Keys: What’s The Difference?
A scale is a list of a series of consecutive notes adding up to an octave, based on and named after its first note, the root note, and its mode (e.g. major or minor).
A key is the musical use of the notes of a scale. A piece is said to be in a key, (e.g. C major), when it is largely made up of the notes of the scale (e.g. of C major) and we can hear the tonality of the mode (e.g.major). For more detail, please visit How Can We Tell Which Key We’re In?
I prefer to think of this in reverse priority:
- A key is music, a scale is a list of notes that music is made from.
- A key is the cake, the scale is the ingredient list.
- A scale is the notes of a key, listed in consecutive pitch order.
Keys and scales have the same name, except if you’re writing or playing a scale you say the word “scale” in the description:
- “This piece is in C major” means “this piece is in the key of C major”.
- Else you would say “play the scale of C major” or “play the C major scale”.
In other words, when talking about actual music we say “key”, not “scale”.
Practical Tip: To easily play in a key you need to be familiar with its scale.
A Scale Has A Key
Since a scale is also a basic melody, a scale itself is in a key. For example, the scale of C major is in the key of C major.
Unless we’re actually playing scales, we talk in terms of keys rather than scales.
Key Signatures
Apart from C major and A minor, other major or minor keys require some notes that are sharps or flats. So far, we’ve written them in before each note. That’s no big deal if it’s just a scale but in a piece, some of those notes might be used many times. It’s hard work when writing and the music ends up looking cluttered.
A key signature uses the space on the stave just after the clef, before the time signature or any notes, to store the sharps or flats of that key for the whole length of the stave. Now they don’t need to be written next to the notes. The music looks cleaner and it’s quicker to write.
A key signature is a list of the sharps or flats used in a key.
The note naming rule states that each letter is only used for one note in the scale (7 scale notes, 7 letters), so the scale notes which are NOT in the key signature are naturals.
For example, the key signature of D major is 2 sharps, F# and C#. All the other letters are naturals.
Note: unlike time signatures, key signatures are written at the start of every stave.
The notes of a key can be played at any octave. If that note is a sharp or flat, it’s symbol is written next to the note; at the same octave as the note. In a key signature, however, a sharp or flat is only ever written at one particular octave and it applies to all octaves. It simply tells us that, for a given key, that note is a sharp or flat.
A key signature is a shortcut for writing out a scale. If we start on the root note and play the notes of the key signature, we’re playing the scale for that key.
It’s important to check the key signature, else you may play some wrong notes!
Here are two scales that look the same apart from the key signature. Carefully read the notes as you listen. In these two scales, every note is different because of the key signature!
The Order Of Sharps and Flats
The sharps or flats in the key signature are always written in the same order, regardless of the order in which the notes are played in the scale, and always in the octave shown below.
For sharps, the order is F# C# G# D# A# E# B#. F# is always the first sharp. Each sharp is the 5th letter above the previous sharp.
For flats, it’s the reverse, Bb Eb Ab Db Gb Cb Fb. Bb is always the first flat. Each flat is the 5th letter below (or the 4th letter above) the previous flat.
Don’t worry if you can’t remember all this, we’ll come back to it later…
Let’s look at A major, for example. In the scale, C# comes before F#, but in the key signature, F# appears before C#.
One big advantage to having a set order is that a player only needs to glance at the key signature to know which notes are sharps or flats. If you know the order, you only need to see how many there are.
Here’s the key signature order on the stave in the treble and bass clefs:
Note the octave where the symbols are written. For example, F# is written in the high octave rather than the low octave.
Why This Order?
Let’s say we worked out every major (or minor etc.) scale by counting semitones. If we looked at them all we would notice three things:
- There are no scales with both sharps and flats.
- The number of sharps/flats is unique. For example, there is only one major scale with 3 sharps.
- Sharps and flats are cumulative. Once a sharp (or flat) is used in one scale, all the scales with more sharps (or flats) include that one.
We can reshuffle our list of scales in increasing key signature order. Here’s what the list of major scales looks like. To save space I have listed their key signatures rather than the whole scale:
Note: In the next post we’ll look at key signatures for minor keys as well as some shortcuts for learning key signatures.
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NEXT LESSON: 12. Major Keys And The Cycle/Circle Of Fifths
PART 1 CONTENTS: Basic Music Theory Course Contents