TBD 01-03-15 (posted 15-03-15). Download your study notes folder for TBD 01-03-15 here.
The right hand uses scale tones sharp-2, 3, R, flat-7 and 5 only in the standard I–IV–V chords, which in key G are G, C and D.
The bass (left hand) uses only roots and fifths - either fifths above or fifths below.
Note that: The fifth (chord/scale tone) below the root is to be found only a fourth (interval) below the root! An inverted fifth = a fourth.
Here is the riff in G
Copy the fingering or get it from the MS. The fingering allows a very 'sticky' hand action and creates a sustained sound without using the sustain pedal - which is not, generally, much used in popular music keyboard.
The simplicity of the material in this riff make it an excellent candidate for transposing.
Transposing is the mother of musical skills. Knowing a piece of music in two keys means you really do know it - and examining the same piece of music in two different keys truly lays bare the workings of musical harmony.
The music for the version in A is not provided. You need to work out what scale tones sharp-2, 3, R, flat-7 and 5 in the I–IV–V chords of key A are - or just copy the video or MidiPiano performance of the riff MIDI file and let it 'sink in'.
Again, this is twelve-bar music but far removed from boogie, rock'n'roll etcetera. Twelve bar is a great way into popular music generally.
This riff makes a good backing for a vocal. Write a lyric and see if you can play and sing at the same time, or just sing along to a looped MIDI-as-audio playback.
Notice the two different lengths of the 'repeat and fade' outros in the two versions. Which do you prefer? Composing is a whole series of little decisions like this.