Two boys tell Maryellen she won´t win the science fair since she´s a girl. Maryellen and a friend prank the boys by making a newspaper of an alien attack, and dressing up as Martians, like on I Love Lucy.
Maryellen builds a baking soda rocket as her project. The next day, she discovers the boys demolished her project
Comforted by her teacher, Maryellen draws elaborate diagrams of her project, and gives her presentation, emphasizing the possibility of space travel. She wins, beating the boys.