Lesson 9: More on sharps and flats

- [Instructor] If we have music with two sharps in the key signature, those sharps are always F and C. Here is a minuet from Mozart's Posthorn Serenade. Notice the two sharps at the start of the movement. If we didn't have the two sharps at the start of the movement, look at all of the accidentals we would have to add. By putting the F and C sharps at the beginning of the line, the music becomes much easier to read. ("Posthorn Serenade" by Mozart) If we have three sharps in the key signature, the three notes that are sharped are F, C and G. This is the pattern. One sharp is an F. Two sharps, F and C. Three sharps, F, C and G. Four sharps, F, C, G, D. Five sharps, F, C, G, D, A. Six sharps, F, C, G, D, A, E. And seven sharps, F, C, G, D, A, E, B. With flats the pattern is one flat is always B as we've learned. Two flats, B and E. Three flats, B, E, A. Four flats, B, E, A, D. Five flats, B, E, A, D, G. Six flats, B, E, A, D, G, C. And seven flats, B, E, A, D, G, C, and F. I will analyze all of this for you in future lessons. Look at the second movement of Tchaikovsky's 4th Symphony. Notice the five flats at the beginning of the line. Look at all of the notes that are affected by those five flats being in the key signature. ("Symphony No. 4" by Tchaikovsky)