What are some themes/symbols in the story "Sir Gawain and the Green Knight"?
There are many different themes throughout the story that you could use. There is the theme of courtly love, where a man "courts" a woman by showing her adoration, affection, and performing heroic deeds in her name. In return, she offers him teasing reciprocations, tokens of her affection (a scarf, a ring, some other item that the knight then wears into battle for good luck). So, you could discuss this notion in regards to the lady of the castle, or even to Guinevere, who Gawain respects and honors at the beginning of the story.
There is also the theme of gallantry or knightdom, and how the knights of the round table were supposedly full of honor and integrity; the green knight himself mentions this and challenges it. You could discuss whether Gawain lives up to that reputation.
So those are a couple possible ideas that you could use. I also provided a link that discusses in depth the theme of heroism, and the hero's journey. Not only does the link provide the idea for that essay, but a possible outline with examples. Cool, right? :) Check it out-I think it'll be helpful. Good luck!