Theme and variation is a musical form where a main melody, or theme, is presented and then variations of that theme are played by altering different musical elements. The document discusses Haydn's Symphony No. 94, also known as the "Surprise Symphony", where the theme is presented and then varied through changes in dynamics, shifting between major and minor keys, adjustments to rhythm, pitch, tempo and other techniques. The class is encouraged to create their own variations on the theme "Twinkle Twinkle Little Star" to experience theme and variation composition.