The Students
The students symbolize people who are eager to learn and progress in their chosen field. They are presented as being dedicated and attentive but are criticized heavily by Maria.
Feeling
For Maria, feeling is the key ingredient of musical success. She emphasizes the singing must be inspired by some kind of feeling and criticizes her students if she feels this is lacking.
Microphones
Microphones symbolize fake musicianship, according to Maria. She tells her class that she does not use microphones herself as she doesn’t believe in them.
Pain and success
In Master Class, opera singer Maria is teaching her students; in her teaching, she often associates success with pain. She is attempting to express the idea that art often requires some sort of sacrifice and personal investment, however, she arguably goes a bit overboard with some of her criticisms.
An example of Maria associating pain and success is when she tells the story of her walking during WW2, despite not having shoes. As a result, her feet bled, and she uses this as an example of the strength and discipline needed to be an opera singer.
Maria
Maria herself represents a dedicated artist, while also exposing the fact she is a diva. For example, she is demanding of the crew and is unsatisfied with most things. She asks the crew for some water, a cushion, and a footstool due to her dissatisfaction.