Acidification of Freshwater Streams and Lakes

Katy Olsen, Pierce College

This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see

This page first made public: Oct 9, 2012


Students will research the acidification of freshwater streams and lakes, identify at least one of the sources and determine how their daily activities contribute to the problem. The students will work in groups of four to design a laboratory procedure that examines a potential solution to the problem, being sure that their data would be meaningful. The group will split into two smaller groups to perform the laboratory and the two groups will compare their results. The students will present their research at the end of the quarter in both a short paper and a presentation.

Learning Goals

Chemistry "Big Idea": Acid/base chemistry in aqueous solutions.

Sustainability "Big Idea": Environmental stewardship, responsibility.

Context for Use

This assignment was written for students in the third quarter of a general chemistry series, which means that they had a background in thinking about chemical reactions and problem solving. If the assignment were modified to give more direction, especially in the laboratory portion, it could be appropriate for an introductory chemistry series as well.

Description and Teaching Materials

Introduction and Overview

This activity allows the students to learn library skills, including the identification and study of scientific, peer-reviewed sources. The students are also given the opportunity to develop laboratory procedures based on a problem which they would like to solve. By examining their role in the problem, the students are able to recognize that their activities may contribute to environmental problems. The students will have a chance to practice effectively communicating their research findings and the results of their experiments to their fellow students.


This assignment was continued throughout the quarter and the research portion was conducted primarily outside of class and the laboratory portion was completed in two laboratory session (4 hours total). One of the librarians gave a presentation on one of the lecture days (1 hour) regarding library research and the students were given one laboratory period (2 hours) to do research in the library while the instructor was available to answer questions. The student presentations used two lecture days (2 hours total).

Here is the timeline for the assignment:
Week 2 - Students are given a short article discussing some of the sources and effects of water pollution to generate starting points for their library research. They are then given a short presentation by one of the librarians on doing online searches and what constitutes a scientific, peer-reviewed journal. Students are given time to do research in the library while the instructor is available to answer questions.

Week 6 - Students turn in the procedure for the lab they developed so that the instructor can ensure that the appropriate materials are available in the lab.

Week 7
- Students perform the lab they designed and discuss results with other group members.

Week 8
- Students perform the lab which was modified or re-designed based on the results of their previous experiment.

Week 10
- Students turn in a research paper about the research they did and the results of their laboratory experiments and give a short (10 minute) presentation to the class.

The Assignment

Students will research the acidification of freshwater streams and lakes and will design a laboratory procedure which examines a potential solution to the problem. By looking at the acidification and then a potential solution, the students will be studying acid/base reactions in aqueous solutions. They will also examine their role in the problem which incorporates the sustainability "big idea" of environmental stewardship. After they see the results of their experiment, ask them to examine the feasibility and ramifications of that solution. It is hoped that they look at not only the chemistry behind the solution, but also think about the social justice issue of who would actually do the cleanup and who would pay for it. The students will present their research at the end of the quarter in both a short paper and a presentation.

The intention with this activity is that the students start thinking about the environmental effects of their actions and how their behaviors can be compounded into a situation which is harmful for plant and animal life.

The Learning Activities

Setup for the Assignment:
Students are given the "Water Pollution" article from the McGraw-Hill Encyclopedia of Science & Technology. It defines some specific terms about water pollution (point sources, different types, etc) and gives them a base to work from for the library research portion.

A librarian will give the students a 25-minute presentation about the resources available in the library and explain what constitutes a peer-reviewed scientific journal. The students are given time to do some research on their own while the librarian and instructor are available to answer questions.

Acidification of Freshwater Research Paper and Lab (Microsoft Word 29kB Nov1 11)
Rubrics (Microsoft Word 43kB Nov1 11)

Teaching Notes and Tips

Overall, the assignment went well, students learned a lot about laboratory design, acid/base chemistry and how difficult environmental problems can be to solve. The assignment helped the students feel more connected to the material and recognize that the environmental problems are caused by all of us and that while the solutions to fix a problem may appear simple, they can be very complex. Final presentations and papers were impressive, the students designed some creative procedures and while some definitely worked better than others, they were very involved in the learning process. Some of the areas for improvement of the assignment are:
  • The students have had difficulty recognizing what constitutes a peer-reviewed scientific journal even after having it explained by one of the librarians. How this could be explained more clearly should be contemplated.
  • The assignment could also be applied to salt water systems, which is something that the students may be hearing about in the news due to the increasing acidification of the ocean due to carbon dioxide. As there is not much acid rain or mine drainage in the Pacific Northwest, the students may be able to relate better to the acidification of the ocean.


The following rubrics were used to assess the assignment: Research Paper, Presentation, Lab Procedure. See Attachment in the Activity Description and Teaching Materials section.

References and Resources

College Library and Librarians

Environmental Protection Agency website