Unreasonable: Your 6-month-old will sit quietly (or sleep) in her car seat for a three-hour drive.
Reasonable: She'll probably get cranky—especially if you're stuck in traffic. One of you may have to sit next to her and sing or find other ways to keep her entertained.
Unreasonable: Your 4-year-old will be adorable playing the role of the Itsy-Bitsy Spider in his preschool play.
Reasonable: While you're waiting with your video camera in the first row, he'll become hysterical and refuse to walk onto the stage.
Unreasonable: Your 2-year-old will be the cutest little flower girl in your sister's wedding—walking down the aisle and posing for photos like an angel.
Reasonable: She'll get overwhelmed by all the attention, need you to carry her down the aisle, pose in very few group photos, and will be out of her dress before dinner is served.
Unreasonable: Soon after you've finally ditched diapers during the day, your child will be able to sleep through the night wearing his undies.
Reasonable: Potty training usually comes in two parts: daytime and nighttime. It may be months—even years—before he's dry all night.
Unreasonable: Your 3-year-old will sit at the table for a family dinner and listen to the grown-up conversation.
Reasonable: She may only last 15 minutes. Give her a toy or a coloring book to keep her amused, or let her be excused from the table.