KS2: Improvise music for typical pantomime episodes. For a quarrel involving slapstick, you might convey the deadpan surface seriousness by using a regular pulse, and the comic eruptions by adding weird harmonies or sliding melodies. For a transformation scene, make the music change from wooden sounds (xylophones and woodblocks) to metal (glockenspiel and bells), or from the minor to the major key - or both at once.
KS3: In groups of three or four, mime the walks of classic commedia dell'arte characters - the Capitano's blustering swagger, Pantaloon's bumbling shuffle, Columbine's elegant glide. Take turns to improvise repeated rhythms to match the movements, then add melodies that arise from the rhythms.