Ave Maria by Charles Gounod is actually an adaptation of the first prelude from Bach's Well-Tempered Clavier. The piece has nothing in common, but is often confused with the “Ave Maria” by Franz Schubert - though this piece was originally titled “Ellens dritter Gesang”. Gounod’s Ave Maria is often performed as a duet, as the original prelude by Bach already demands a keyboard players full attention.

Level 1.5 has crotchets in the accompanying left hand.
Level 2 has quavers in the left hand.
Level 2.5 has semiquavers in the left hand.
Level 3 has a left hand that is very close to the original Version of Prelude No.1 that this piece is based on.
Level 3.5 is very difficult to play: the left hand is identical to Prelude No. 1 by Bach (written for two hands). The melodic line is also harmonised.