Flight of the Bumble Bee by Nikolay Rimmsky-Korsakovā¦just joking :D
These four pieces are easy and popular. (my 8 years old daughter can play them without any problem).
ODE TO JOY by Ludwing Van Beethoven.
DETERMINATION by Daniel Gottlob Turk
MARCH by Daniel Gottlob Turk
MELODY. Op.218, No.18 by Louis Kohler.
It all depends on the arrangement, try to get the "easy piano versions" or Level 1.
Or try this link...http://www.classicalmidiconnection.com/cmc/
Good luck, man!
.