Answer:
Students should recognize that the chant, unlike blank verse, uses end rhyme and that the lines are shorter than blank verse's iambic pentameter (five-beat) lines. They may speculate that Shakespeare uses this form because a witches' chant should by its nature be more musical and should not try to approximate the sound of spoken English (the way blank verse does) and that the strong, repetitious rhythm and rhyme adds to the lulling sense of the supernatural spell.
