in this video i will be explaining the purpose of key signatures and how key signatures are laid out on the treble and bass clef staves specifically i'll be focusing on c major f major g major and d major it's important that you know how to calculate scales before watching this video if you need to have a look at my other videos which explain these so what is a key signature well let's look at the very start of a piece of music there are three pieces of information here the clef the key signature and the time signature the key signature is very important for reasons i'll explain in a moment but to start with just be aware that a key signature is placed after the clef but before the time signature a lot of students often place them in the wrong order this key signature has two sharps in it f sharp which i've highlighted blue and c sharp which i've highlighted red the purpose of this key signature is to tell a musician to play all of the f's and c's in the music as f sharps and c sharps if there was just one flat b-flat this tells the musician to play all of the b's as b-flats now the key signature can't just randomly contain any notes and neither can it have a mixture of flats and sharps like this there are some very strict rules relating to key signatures and this video explains precisely how to lay out sharps or flats in the key signature let's look at a scale of g major here it is in the treble clef and if you worked out this scale correctly you'll know that there is an f sharp here at the moment this is g major ascending ascending because we're going upwards without key signature in other words there is no key signature after the clef here and if you're wondering why there is no time signature musicians often leave out a time signature when they are writing scales like this let's assume you are asked to write this scale with a key signature well g major has one sharp in it the f sharp highlighted red we move the sharp so that it is placed after the clef notice how it is placed at the top of the stave rather than the bottom this is very important more about this later and here is our key signature with the key signature in place there is no need to write a sharp before the f as the key signature tells us to play all of the f's as f sharps now you might be wondering what difference it matters whether the sharp is placed here as part of the key signature or here as an accidental in front of the f well imagine if you were playing this piece of music there are lots of f sharps in it in fact this piece of music is in the key of g major but rather than using a key signature all of the f sharps have been written in therefore an alternative rather than writing in all of the sharps would be to use the key signature of g major this means we can take out all of the sharps in our music as the key signature tells us to play all of the f's as f sharps this makes the music much easier and quicker to read i'll pop this key signature of g major at the bottom of the screen where i'll be placing all of the key signatures we look at in this video before we move on let's just quickly look at how we lay out a g major key signature on the bass clef like the treble clef notice how the sharp is placed towards the top of the stave it is never placed down on the bottom f more of the shortly i'll pop this at the bottom of the screen as well let's have a look at another key d major this time it is descending you can see that there is a c sharp and an f sharp in our scale we can move both of these sharper notes to form our key signature and it looks like this now a few things to note here the f sharp is placed first key signatures with sharps always always always start with an f sharp so putting the c sharp before the f sharp like this is wrong secondly the f-sharp is always placed at the top of the stave thirdly the c-sharp is always in the middle of the stave if it were the c-sharp above it would need a ledger line key signatures never use ledger lines and finally the c sharp is placed after the f sharp not underneath it when you're ready to move on to more complex key signatures be aware that sharps and flats appear in the same order so by remembering these rules will help you to quickly calculate other key signatures i'll pop the d major key signature at the bottom of the screen here is the key signature of d major but in bass clef notice how the same rules apply the f sharp is placed first and it's at the top of the stave the c-sharp is placed below the f-sharp and after not before i'll put this bass clef key signature of d major at the bottom of the screen as well how about f major here it is ascending in the bass clef this time there is one b flat in the scale we can move it to form a key signature however does the b flat sit here or here well the answer is the one on the left the reason will become clearer when you look at a key which has two flats in it but if you are interested for the moment it is because if we put the b flat at the top of the stave this will cause the next key signature note to have a ledger line through it as you know this is not allowed i'll pop this correct key signature at the bottom of the screen in the same place i'll also show you the key signature for f major but with a treble clef again notice how the flat sits in the middle of the stave a higher or lower b would require the use of a ledger line finally how about c major well this scale has no sharps or flats in it so this one is very simple if there's no sharps or flats in the key signature it is c major unless it's a minor but i'll look at a minor in another key signature video but just remember c major is still considered to have a key signature there are just no sharps or flats in it like those i'm adding here at the bottom of the screen so before we finish just to recap and look at some important rules firstly key signatures help declutter music from the overuse of sharps or flats secondly key signatures can help you determine what key like c major f major or d major etcetera a piece of music is in thirdly in key signatures with sharps the f sharp always comes first and is placed at the top of the stave and finally in key signatures with flats the b-flat always comes first i do hope this video has been useful to you do have a look at the next video in this series about key signatures which explains both major and minor key signatures with up to three sharps or flats in them in the meantime thanks for watching