Have your students ever wondered what NASA scientists do? Have they asked you what their science and mathematics lessons have to do with the real world? This unit about Earth's atmosphere can help to answer both of those questions. The unit described here showcases "content specific integration" of science and mathematics in that the lessons meet content objectives from both science and mathematics. The content objectives for mathematics from the new Common Core State Standards for Mathematics are to understand and reason about ratio concepts, including converting measurements, solving problems involving area, and representing real-world problems graphically using one quadrant. The content objectives for science are the properties of Earth's atmosphere and understanding about science and technology. In this unit, students will explore Earth's atmosphere with an air-pressure activity. (Contains 3 figures and 4 online resources.)