The theme melody of Ping Pong Variations appears five times, and the melody is very lively and cheerful. "Ping Pong Variations" is a piano listening piece in the seventh unit of the human version. The theme music is based on the children's song "Little Balls Shine Silver", which shows the children's happy expressions and skillful skills when playing table tennis. Piano music refers to works written for the piano or adapted for the piano, sometimes played with other instruments at the same time. The piano is a keyboard instrument in Western classical music and is known as the king of musical instruments. It consists of 88 keys (52 white keys, 36 black keys) and metal string soundboard.