Here's one example of a very simple keyboard improvisation using notes of the G major pentatonic scale in the RH. Perfect 5ths in the G and F position accompany in the LH.

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How to play this improvisation:

1) Let your LH play a perfect 5th in the G position.
2) While you're sustaining those notes, let your RH make melodies by playing any notes of the G major pentatonic scale.
3) When the LH notes fade, play and sustain them again.
4) Keep it simple!
5) Yet, if you'd like to change the sound of the LH, simply move it down a 2nd, to a perfect 5th in the F position.Notice how the exact same RH melody notes G,A,B,D,E sound different when played against these different LH notes.