Final answer:
Two notable elements of ancient Greek theater include the chorus, serving as a narrative tool, and the use of masks for character differentiation and voice amplification.
Step-by-step explanation:
Two memorable elements of ancient Greek theater are the chorus and masks. The chorus originated from the dithyrambs sang in honor of Dionysus, eventually evolving into a narrative element in plays, resonating through tragic and comic performances alike. Masks were fundamental for actors to portray multiple characters and to amplify their projected voice, their exaggerated expressions helping to convey emotion to distant audience members in large, open-air theaters.