US Geological Survey
U.s. Geological Survey: Water Science for Schools: Acid Rain
An introduction, aimed at upper elementary- and middle-school learners, to acid rain. [Click back to home to access the site in Spanish.]
Other
Environment Canada: What Is Acid Rain?
A thorough explanation of acid rain with a focus on the following topics: what is acid rain, the pH scale measures acidity, what does acid rain do, and what can I do about acid rain.