This writing prompt has a few pieces to it. One part steers you to write a summary of the story and explain what you have learned. Feel free to explain the lesson that you feel that you learned from reading this story. You could explore the lessons the story shows about bullying, isolation, and/or jealousy. These are powerful thematic elements in the story, and readers are shown just how cruel people can become due to an emotion like envy.

You could also explore lessons learned about mob mentality. Surely there were kids in the class that knew their actions were wrong, but they were afraid to stand up to the group, or they were moved along to act cruelly for no other reason than they succumbed to the mob.

You could even explore lessons about revenge. The class is jealous of Margot and her experiences, and they get revenge against her by preventing her from seeing the sun. This revenge theme could be applied to the hypothetical ending/conclusion that the prompt pushes you to write. It might be an interesting additional ending to have Margot seek out some kind of revenge against her class.