Prologue: This is the introductory scene to a play. Usually it involves a limited number of characters that explain the necessary history to understand the current drama. In Medea this would be the scene between the Nurse ("O how I wish that ship the Argo/had never sailed off to the land of Colchis"), the Tutor ("Old slave from my mistress’ household,/why are you here, standing by the gate"), and Medea herself ("I can’t stand this pain, this misery./What do I do? I wish I could die!").
Parados: The first song spoken or sung by the chorus. This scene begins in Medea when the Chorus Leader comes on.
First Episode: In an episode, characters and chorus members talk and advance the plot. It's important to remember that in Greek theatre no more than 2 or 3 characters can be onstage (besides the chorus, who weren't really onstage at all but in a separate place called the 'orchestra').
Choral Ode: A song or chant performed by the chorus. Usually this would be combined with a dance or ritual of some kind.
Second Episode: The second scene between characters.
Choral Ode: The second choral ode.
(...) The rest of the play should go back and forth between episodes and choral odes.
Exodus: Finally, at the end of the play, the chorus gives some piece of final wisdom. Here is the exodus from Medea:
"Zeus on Olympus,
dispenses many things.
Gods often contradict
our fondest expectations.
What we anticipate
does not come to pass.
What we don’t expect
some god finds a way
to make it happen.
So with this story."
Medea by Euripides follows the typical structure of a Greek tragedy. It is performed by three actors who play all of the individual roles in the play and a chorus that sings and dances as a group. The play opens with a prologue, in which actors set out the main themes of the drama, followed by a parode, or entrance song, sung as the chorus enters the stage.
The main body of the drama alternates between "episodes" in which individual actors engage in dialogue with other actors or the chorus, and choral odes sung by the chorus. Choral odes normally consist of three parts, a strophe, and antistrophe metrically identical to the strophe, and an epode; these are sung and danced by the chorus.
After Medea departs on her chariot, the chorus sings a final epode, or exit song, as they leave the stage.