Falling Hydrogen Ions

Keywords: pH, acid rain; Setting: classroom; Grade Level: tenth grade; Total Time for Lesson: 48 minutes

Concepts to Be Covered

  • Review of pH and pH scale.
  • What acid rain is and what the effects are on wildlife, soil, and vegetation in Pennsylvania.

Goals for the Lesson

  • Students will be able to define pH and use the pH scale to interpret the amount of hydrogen ions in a solution.
  • Students will be able to define and discuss acid rain, list its sources in PA and identify its effects on wildlife, soil, and tree forestation in PA using specific examples.


  1. Class will begin with a 10-minute review of the concept of pH and the pH scale gone over in a previous class. The review will include the terms, hydrogen ions, OH, hydroxide ions, logarithmic pH scale, aqueous solution, concentration, properties of H2O.
  2. After this review there will be a brief Q&A discussion (approx. 10 minutes) on acid rain and what the students know about acid rain and its effects. This will provide the teacher with an assessment of what the class understands and misunderstands about acid rain.

Lesson ( approx. 30 minutes)

  1. Each student will receive a copy of Acid Rain The Pennsylvania Connection from Penn State Cooperative Extension. Students will then be divided into groups of two or three, and each group will be given a section to read. The pamphlet will be divided into the following sections for reading:
    • Welcome to Acid Rain Central and the Acid Rain Chain
    • Measuring Acidity and Acidity in the State
    • Effects on Forests and Forest Soils (this can be divided between two groups)
    • Effects on Ground Water
    • Effects on Surface Waters
    • Effects on Aquatic Life
    • Effects on Drinking Water, the Future: Where Are We Heading?
  2. Each group will highlight what they believe is the most significant information they learn from the reading and be prepared to share this information with the rest of the class in a final topic discussion. No writing is necessary and nothing will be handed in; this is for discussion purposes only. The teacher will suggest that each student highlight the main points brought out in discussion in their pamphlet.
  3. Each group will present their information to the rest of the class. The class will be encouraged to asked questions of each group as they present they material. The teacher will act as the facilitator of this discussion and will make sure to point out and review the key information needed to fulfill the goals of the lesson.


(remaining time and/or beginning of next class period)

  • The teacher will explain what information will be on the quiz and will highlight all key concepts in a brief summary/review session.

Optional Lab Activity

  • Students will collect or have available a sampling of local ground water to perform a pH test on. This lab can be done at a time when the weather permits a sampling of local rain water before if hits the ground. This is a very brief outline of possible lab activities used to reinforce the concepts of the lesson.


Schneck, Marcus, Joy Drohan, and William Sharpe (1999). Acid Rain: The Pennsylvania Connection . University Park, Pa.: The Pennsylvania State University.


Jack Lyke, State College Area School District