Learning to Look at Art

"What is the benefit in engaging in the process of art criticism?" In Art 6, the first artwork we look at is "Masterpiece" by Roy Lichtenstein. We learn how to critique a work, going through the four steps: describe, analyze, interpret, evaluate. They're always surprised with any work we critique, that there is more there than we first realized. The final step is to make their own parody of this work, putting themselves in the place of the artist. Here's mine, right below Roy's.

More questions:
How does relevant contextual information aid interpretation? How do we decide what is relevant?