[MUSIC] We've been writing major scales using accidentals. That is, sharps and flats placed before the notes like this. In order to have our whole step, whole step, half step, whole step, whole step, whole step, half step pattern for our major scale. We need the notes A flat, B flat, C, D flat, E flat, F, G, and A flat. It sounds like this. DO RE MI FA SA LA TI DO. If we were to write a tune in the key of A flat major, we would use these seven notes. Let's write Twinkle, Twinkle Little Star. With soulfish syllables it goes like this. DO, DO, SO, SO, LA, LA, SO, FA, FA, MI, MI, RE, RE, DO. Let's write that in base clef using accidentals. It starts DO, DO, then we said SO, SO. The fifth scale degree, E flat, is SO, then LA, LA, SO. Can you figure out the rest? FA, FA, MI, MI, RE, RE, DO. Here it is. Every time we got to one of the notes from the scale that was a flat, we had to write a flat sign. Wouldn't it be nice if we could just say that from now on all Bs, Es, As and Ds are flat unless told otherwise? In fact, we can. The four flats shown here immediately after the clef are called a key signature. Written on every staff of the score, they tell the performer to use the seven notes from the diatonic set that has A flat as DO. As we have seen, that means the major key of A flat major. As I'll discuss in the next lecture, it also means F minor, B flat dorian, C phrygian, and so on. Several things to notice about the key signature. First, it's always the first thing on the staff after the clef. Second, the sharps and flats always are placed in the order they appear as we add sharps to major scales. That is, the major scale with one sharp, G major, has an F#. The scale with two sharps, D major, has F# and C#. A major has F#, C#, and G#, and so on. The scale with one flat, F major, has a B flat. Two flats, B flat major, has B flat and E flat, and so on. Remember the order of sharps and flats from several lectures ago. The sharps was F, C, G, D, A, E, and B#. The flats were B, E, A, D, G, C and F. So, when we add sharps, we do it in that order. F, C, G, D, A, E, B, here they all are. When we add flats we do it in this order, B flat, E flat, A, D flat, G flat, C, F flat, here they are. Notice the order of the flats is reverse of the order of the sharps. So backwards the flats are F, C, G, D, A, E, and B. You should simply memorize the order of sharps and the order of flats. Be able to say it quickly. F, C, G, D, A, E, B and B, A, D, G, C, F. Don't use mnemonic or word games, fat cats going down alleys and all that, just memorize them. The third thing to notice about key signatures is that they are always written as a zig-zag on the lines and spaces shown here. The accidental zig and zag, at the same time, on both the bass and treble clef. For sharps, starting on F#, that's down, up, down, down, up, down. For flats starting on B flat it's up, down, up, down, up, down. Each sharp or flat on a line or space refers to all sharps and flats in all octaves on that staff. The clefs and key signatures go on every line, the meter signature doesn't. Finally, if we have a grand staff, we must put key signatures on both staves. In the next lecture, we'll practice writing and reading major key signatures. Before then, though, I want you to figure out what the key signature of B major is. For now, you may need to build a B major scale using the major scale interval pattern. I have said it enough times by now that you should know it, whole step, whole step, and so on. The notes in a B major scale are B, C#, D#, E, F#, G#, A#, and B. That's five sharps. Since you have memorized the order of sharps, you know that five sharps must be F, C, G, D, and A. Here they are, F, C, G, D, and A. Now you try some questions about key signatures on your own. In this first lecture about key signatures, you learned that key signatures are used instead of filling the page with accidentals. You learned where the key signature goes on the staff and how to write the characteristic zig-zag pattern. You learned that you should memorize the order of sharps and flats. B, A, D, G, C, F for flats, F, C, G, A, E, B for sharps, so that you can easily write them on the staff. And you figured out the key signatures of several major scales. [MUSIC]
