In this brief article, the author, a science teacher at F. C. Hammond Middle School in Alexandria, Virginia, describes how the setting up of a simple science experiment on the first day of school can get students excited about learning science. The experiment involves heating a small amount of water in a flask, then covering the opening of the flask with a balloon, and setting it aside to cool. As the trapped air in the flask cools, the balloon is pushed into the flask and inflates inward. Students are instructed to ask questions of the teacher in order to figure out how the balloon inflated inside the flask. This simple demonstration not only can make learning science enjoyable, it can also provide the teacher with a rough idea of students' science background.