Here's a simple exercise to make sure we're on the same page. :)
View the full lesson at Key Signatures Recognition | JustinGuitar
The video playlist shown on all lessons for this module has the duration incorrectly listed as 30:00, should be 0:30.
Can you figure out if the key is sharp, flat, or natural just from the stave? Or you use that just to get the letter of the key, then you have to apply your knowledge of the chart to determine the rest?
When we use the Major Scale Worksheet to determine the number of sharps or flats a key has, we count them from I-VII, and I again repeats. So we say F# has 7#'s. On the stave, it shows 6#'s for F#. This is simply because they don’t count the F# twice? It is just a difference that we need to remember between the worksheet and the stave, in how they are counted?
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No there is no difference between the stave and the worksheet. When you count the sharps and flats on the worksheet you also don’t count the second F#. So even on the worksheet the key of F# has 6#s not seven.
An easy way to check yourself on the worksheet is they are set out in a particular order where each new line is going up by one sharp. C having none, G having one, D having two etc.
Hope that makes it a little clearer
Hi Fncanuk,
The first thing to remember that each major scale* has 7 notes or degrees (marked with Roman numerals). Not 8, but 7. When you see degree I the second time, that’s the octave of the root note, in your example F#. I think this is displayed in the worksheet for the sake of convenience so that everyone knows if they are filling it in correctly, and also to reinforce that each “letter” appears only once in a scale. I.e. in the key of F# major they don’t put Gb as the octave of the root.
Also, there’s the mnemonic of using the last # as an aid to determine the root note of the given key. Take G major as an example: it has 1 # on the 5th line which is the place of the note F. It means that the G major scale has F# sharp in it, and the key is one semitone higher than the last sharp in the key signature.
The same in D major: the last # is in the 3rd space which is the place of the note C. So the D major scale has F# and C# in it, and the key (D) is one semitone higher than C#.
If we apply this to the key signature of F# major, we’ll see that the last sharp is in the 4th space which is the place of the note E, and that means it’s an E# (enharmonically equivalent to F). And F# is one semitone higher than E#.
Hope this makes sense 
- Of course, there are pentatonic major scales with only 5 notes.
@dave.pritchard101 @Jozsef
Okay thanks guys!
So really, this version of the FCGDAEB mnemonic does work and includes all keys.
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Frankly, I didn’t get the reason why should we learn key signatures. I am asking myself why should I know this? Can you people help me to understand why this is important and what would I miss if I didn’t learn them?
Hello @ErkanBolt welcome to the Community.
If you’re a pianist, a trombonist, a cellist, a saxophonist, this is the stuff of life.
As a guitarist, the breadth of usual keys for most music (and this is a very generalised simplifcation) is much narrower and you can pretty much get way with only knowing about the keys of C, A, G, E and D.
But, in knowing what it takes to deduce and work with those keys, you have the skills and tools to do it for any key. So why not? Besides - if you’re playing guitar in any setting where there is a brass section, for instance, you can be guaranteed to be playing in the keys of Bb or Eb for starters. That is the way they are tuned.
Hope that helps.
Cheers 
| Richard_close2u | JustinGuitar Official Guide
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As GToz stated, the video length is listed at 30mins. I seen the length and waited until I had free time to do the lesson. 30 mins is quite the chunk!Anyway, made some free time, put on the coffee, then sat down to find out it’s 30 secs! Grrrr could’ve done it ages ago. You should probably change that…
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Just seen this as well. Can this be updated as I was expecting a 30mins. video
Hi,
I still remember this one,…it felt a bit like a free/extra hour at school when your boring maths lesson ( 
sorry R )was cancelled,…and you could go out and play on the grass,
Greetings,Rogier
just a repeat of what has been mentioned already so that people can plan their time, the screen showing the video list shows this video as 30:00, but the actual video duration is 0:30, so the video list needs to change.
> Have a look at the Key Signatures below.
> Can you tell the Major key shown by each.
With Mr. Cato’s slick key diagram? Probably so.
By looking at the notation? No. Why? I don’t know notation.
Soooooo. Enter Grade School music class from 60 years ago:
Every Good Boy Does Fine (Lines)
FACE (Space)
I’ll memorize this and give the test a shot tomorrow. 
To each their own, but memorizing the key signatures (or at least the ones for common guitar keys, i.e. CAGED) takes about 1 extra week. Also, the order in which the accidentals appear may look familiar, too.
@Jozsef I’m doing this so that I know both ways of understanding key signatures. At some point in time I’m going to tackle reading music notation, so may as well start now. It’s just an exercise in understanding how key signatures are derived based on flat and sharps on the stave. I already have the key signatures memorized.
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Love it. Im so using it.
Thanks
