Keywords: chemical principles, acid precipitation, social and economic issues; Settings: classroom and school grounds; Total Time for Lesson: four standard (40- to 45-minute) class periods; Grade Levels: ninth through twelfth grade

Materials Needed

For Lab (see EPA Lab Experiment #5 Web site ):

  • Garden Soil pH Test Kit
  • distilled water
  • soil samples (from school grounds)
  • measuring spoons
  • small digging tools
  • self-sealing plastic bags (sandwich-size)
  • bag of commercial top soil (to fill in divots from sampling)
  • 3 x 5 index cards (for writing down sample locations)


Concepts to Be Covered

  • Acid precipitation is the product of industrialized societies.
  • pH is a measure of the acidity or alkalinity of aqueous solutions.
  • Acidity can occur in all forms of precipitation and dry depositions can occur.
  • Acid precipitation can damage both man-made structures and natural ecosystems.
  • Acid precipitation causes damage to soil, fungi, plants, aquatic life and most likely, terrestrial animals.
  • Surface waters, soil, and geological formations can "buffer" the effects from acid precipitation.
  • For a price, society can reduce the emissions that cause acid precipitation.

Goals for the Lesson

  • Students will develop a basic understanding for the pH scale.
  • Students will know two sources of acid precipitation.
  • Students will understand the mechanism for acid precipitation formation.
  • Students will be able to list several forms of acid precipitation.
  • Students will be able to list several effects of acid precipitation and explain the actions that cause the damage.
  • Students will be able to define "buffering" and explain how environmental factors can act as buffers.
  • Students will gain an understanding of the underlying social and economic issues beneath the problem.

State Standards Addressed: Environment and Ecology (4.1); Watersheds and Wetlands (4.2); Renewable and Nonrenewable Resources (4.3); Environmental Health (4.6); Ecosystems and Their Interactions (4.7); Threatened, Endangered, and Extinct Species (4.8); Humans and the Environment (4.9); Environmental Laws and Regulations


Direct Instruction for presentation of concepts and for lab and activity instructions.; Hands-on Learning for lab activity; Discussion Group Model for activity to analyze social and economic issues; Out-of-Class Practice in form of study guide questions to be completed as homework


  1. Study guides for Implications for Forest . . . brochure can be graded.
  2. During lab activity, make sure all students are participating.
  3. If you wish to grade the discussion activity, a scoring rubric may be developed and used.
  4. Terminology, causes, and effects can be assessed on subsequent tests.

Lesson Outline

  • Day 1: Introduction, discussion of Acid Rain and Implications for Forest . . . handout
  • Day 2: Soil pH lab (outside and inside)
  • Day 3: Group discussion activity on issues
  • Day 4: Discuss lab results, brief review, discuss issues activity as conclusion, and collect papers and lab results

Day 1: Introduction

  • I comment about the fact that rainbow trout have been removed from the stocking list for some of my favorite streams in Elk County, PA.
  • Other, more subtle changes are occurring in our forests and streams. The effects of these changes may not become apparent until later, perhaps even too late to do something about these changes.
  • The changes taking place are caused by acid rain or more precisely, acid precipitation.
  • Acid precipitation is an old problem that has only been studied in the U.S. for the last two or three decades.
  • Initially, our only source of data was obtained from European research.
  • Some of the first signs of this problem in the U.S. were deteriorating structures and monuments, dying trees located in higher elevations, and sterile, lifeless lakes and streams within the Adirondack Mountains.
  • Pennsylvania receives larger amounts of this precipitation than any other state and unfortunately, also generates large amounts of emissions leading to the problem.
  • We will study this problem from its chemical explanation to a cause and effect analysis. We will suggest solutions and discuss underlying social and economic issues that hinder that application of these solutions toward solving the problem.
  • This lesson will concentrate on the acid precipitation effects on the soil, the forests, and aquatic life.
  • Presentation: Use overhead slide masters from appendix to cover and discuss this lesson.

Day 2: Soil Lab

  • Assign three or four students per group.
  • Refer to EPA Lab #5 Web site .
  • Take soil samples from school grounds. Use areas that will leave minimal impact. Take samples from a wide variety of locations such as from under both deciduous and coniferous trees, from under both landscaped shrubs and open areas, etc.
  • If necessary, fill in resultant holes with soil from bagged top soil.
  • Take bagged soil samples back to classroom for pH testing.

Day 3: Discussion of Social & Economic Issues

  • Divide students into the following teams (three or four students per group):
    • electric utility company
    • elected officials
    • environmental Protection Agency
    • fish commission/forestry & four or five agricultural interests
    • residential consumers of electricity
    • industrial consumers of electricity
    • conservation/ecology groups
    • outdoor recreational users.
  • Allow 15 minutes for teams to separately discuss suggested issues.
  • Previously have written on the chalk board (or hand each group a copy of) the following discussion issues:
    • Additional levels of pollution can be removed from automobile exhausts and from coal-fired electricity generation plants with an increase in cost.
    • Who should pay for this increase?
    • Would you pay for this higher priced electricity if it means cleaner air?
    • Who should pay for research for better methods of removing articulates from smoke stacks?
    • Should we use a less expensive, more abundant, high sulfur grade of coal to generate power?
    • Should we develop alternative forms of energy to generate electricity? Who pays for the research and development?
    • How should pollution laws be enforced?
    • Do we, as a society, need more pollution laws?
    • Would you change your life style to reduce power consumption?
    • If we as a society were to eliminate the causes of acid precipitation, how long would it take the affected ecosystems to recover?
    • If affected ecosystems do not recover, what would you miss from them?
    • What is the main cause of acid precipitation (the same cause of most of the world's other ecological problems)?
  • Allow 20 minutes for the actual discussion. Make sure that each group participates.

Day 4: Wrap-Up

  • Finish and discuss the results of the soil pH lab. Theoretically, soil from under coniferous trees and shrubs such as rhododendron or mountain laurel should be more acidic than soil from under deciduous trees.
  • Briefly review the material from day one.


  • Discuss the social and economic issues that prevent a speedy solution to the acid precipitation problem.
  • The main reason for the acid precipitation problem and for most of the world's other ecological problems has been a rapidly expanding human population and associated advances in technology.
  • The bottom line is that the residential power consumer will be paying for cleaner air, in whatever quantities are dictated by society, in the form of higher electric utility bills, more expensive personal autos, and more in tax dollars to pay for research and enforcement costs.


  • There are eight more labs and several activities attached to the EPA Web site.
  • A suggested activity would involve examination of the trout stocking list for your county and comparing it with lists for surrounding counties. Your local conservation officer may be able to provide information regarding the acidity of those streams, what changes have been made with regard to species being stocked, and whether some streams have been removed from the stocking list.


The Pennsylvania Fish & Boat Commission (2001). Acid Precipitation.

The Pennsylvania Fish & Boat Commission. The Basics of Water Pollution In Pennsylvania. Bellefonte, Pa.: Division of Environmental Services, Fish & Boat Commission.

The Pennsylvania State University and The U..S. Department of Agriculture Cooperating (1984). Acid Precipitation, Implications for Forest Productivity. Pennsylvania Natural Resources 2. University Park, Pa.: Penn State Cooperative Extension.

The Pennsylvania State University (1999). Acid Rain, The Pennsylvania Connection . University Park, Pa.: Penn State Cooperative Extension.

The United States Environmental Protection Agency (2001). EPA's Acid Rain Educational Resources - Science Experiments.


Allen D. McLaughlin, Eisenhower High School, Russell, PA