On slug days, Lauren feels slow and slimy. She feels like everyone yells at her, and that she has no friends. Today there is a different bus driver; Dan and Sachi are sitting in Lauren's seat on the bus; and Lauren's teacher interrupts her reading time. It is definitely a slug day. But not every day is like this. On butterfly days, Lauren makes her classmates laugh, or goes to get ice cream, or works on a special project with Mom. Lauren has Autism Spectrum Disorder (an umbrella term that has included Asperger Syndrome since 2013), and she sees the world differently from many people. Sometimes this makes Lauren want to flip her lid, especially at school, where she learns differently from her classmates. But with support and stubbornness and a flair that's all her own, Lauren masters tricks to stay calm, to understand others' feelings, and to let her personality shine. She even manages to find common ground with her sticky, slobbery baby sister. Best of all, being different gives Lauren insight into the insecurities of the new student, Irma. Award-winning author Sara Leach writes Lauren's endearing story with empathy and humor, sending her flying off like a butterfly into a new chapter of life with a new friend.