Why does a balloon deflate when it is left in a cold car; or why does one have to pump up his or her bike tires in the spring after leaving them in the garage all winter? To answer these questions, students must understand the relationships among temperature, pressure, and volume of a gas. The purpose of the Predict, Share, Observe, and Explain (PSOE) activity is for students to connect the relationships among temperature, pressure, and the amount of gas. Students have many everyday experiences with these relationships, such as pumping up a basketball, but may have never thought of air in terms of pressure and temperature.