In this new scale we keep the F# from G major and add the new C# on the 7th degree.

 The extra sharp is always on the 7th note. If you compare the first half of this scale with the second half (notes 1-2-3-4 with notes 5-6-7-8) You may notice that the semitone arrangement is the same i.e 1-2 (and 5-6) is a Tone: 2-3 (and 6-7) is also a Tone and 3-4 (and 7-8 is a Semitone) These two partitions are called tetra-chords. If you compare the first tetra-chord of D major with the second tetra-chord of G major you will notice that they are the same. This is a rule that occurs throughout the 'circle of' of key signatures on the 'sharp' side - e.g. the final 4 notes of C major (scale) will be the first 4 notes of G major and the final 4 notes of G major will be the first 4 notes of D major and so on.

This is another new major scale Bb major. Here we add E flat to the B flat that belongs to F major. Eb occurs on the 4th degree of the scale. Bb major is an Interval of a 4th (that is if we count all four letter names F-G-A-B) from F to the note Bb we get an interval of a 4th (more about intervals later) As the new flat Eb is also a 4th interval from the previous Bb (in F major) then (if you're following me) you may be able to work out the next 'flat' key. (see grade 3)

Notice that the new flat is written in the top space of the treble clef and correspondingly in the 3rd space of the bass clef