The kids were tumultuously waiting for the sun to come out for the first time in seven years.
Some of the other kids thought the sun was never going to come out so they pushed Margot inside of a closet because they were jealous of her. She remembered what the sun looked like and used to live on Earth. They all live on Venus now where it has rained for 7 years straight.
The kids were bullying her because they were jealous that she remembered what the sun looked like when she used to live on Earth. Margot was protesting and pleading that they don't lock her in the closet.