Modulation and Sequence
Modulation means to change key in the middle of a piece of music. In Leaving cert' we always modulate to the dominant in our melody writing. The dominant is the 5th note of the scale, or soh. e.g. C modulates to G, G modulates to D etc. The simplest way to understand a basic modulation is to introduce the note in the new key that's not in the old one. This note is always Te in the new key and it will always have an accidental in front of it. This Te in the new key must end up on doh in the new key as Te always sounds like it wants to go to doh. Study the examples below.
In a 4 bar phrase context, the easiest place to put a modulation is at the end of the phrase like below. The next phrase would start back on chord I in the original key.
Sometimes the modulation can be spread over 2 bars as below. The implied chords are V - I in bar 3 and V7-I in bar 4. Also notice the harmonic rhythm, the rhythm the implied chords change at. Here they change every 2 beats. This would be very common in 4/4 time.
The following is very similar.