Traditional music is a genre of music categorizing those songs which have evolved over time often through oral tradition, music with unknown composers or music performed by custom over a long period of time. The tune is usually a short instrumental piece, a melody, many a time with repeating sections, and played over and over. In musical style, the common form is AABB also known as binary form which happen to be easy piano lessons for kids to play. Children's (kid's) music has historically held both entertainment and educational purposes. Quite often, the music is designed to provide an entertaining means of teaching kids about their culture, other cultures, good values and behavior, facts and skills. Educational music, is a sub-genre of kids piano music in which songs, lyrics, or other musical elements (such as piano sheet music or piano chords) are used as a method of teaching and/or learning.