The Is Our Rain Acid Rain? unit consists of eight sessions divided into two parts. Before beginning the unit, students complete the Pre-Unit Questionnaire. Then, in Sessions 1-6, they consider pH and begin to find out what acid rain is. They also begin to study its causes. They design and build rain collectors and gauges for measuring the pH of local rain. If the precipitation is frozen, they collect the hail, sleet, or snow and allow it to melt before measuring the pH. In addition, they take a detailed look at how acid rain forms and examine the importance of prevailing winds in moving acid-producing materials from place to place. At the end of Session 6, students send their data to the unit database.

In Sessions 7 and 8, students discover what they can learn from the network data. Further experiments to discover how acid rain affects living and nonliving things and the study of what is being done to solve the acid rain problem give students additional insight into this important environmental and social issue. At the end of the unit, students have the opportunity to present highlights of their studies. They also complete the Post-Unit Questionnaire.