You can read that original short story on Futurism. If you've read the novel, you'll notice some distinct differences.
There is one line in the short story that I wish I'd included in the novel series somewhere. It's something Mary says to her bullying friend:
“Someday, when you’re no longer a child, you’ll understand what you’re saying,” Mindy said. “Someday you’ll understand who you’re talking to. Someday. For now, it’s alright. I understand, and I don’t hold it against you.”