Note: The lesson is designed to be a part of an ongoing study of chemistry and is composed of two segments: the collection of samples in the field and the testing of those samples in the classroom laboratory followed by the analysis of the results. The collection of the samples is best done with a small number of students as it minimizes the costs of transportation and is more ecologically sound in that large numbers of students traipsing around in the stream bed and in the riparian area can have an impact on the flora and fauna. It is assumed that the actual testing of samples will be done with a larger number of students in five or more classes.
- water-testing kits: pH, carbonates, turbidity, nitrates, and dissolved oxygen (only one of each required)
- bottles to collect samples
Concepts to Be Covered
- water quality is measurable
- water quality can be directly related to human activities
- water quality can be improved
Goals for the Lesson
- Students will learn through discovery and analysis how human activities can negatively and positively affect water quality.
- Students will be able to correctly collect water samples from various sources.
- Students will be able to use proper laboratory procedures to test water samples for dissolved oxygen, nitrates, pH, carbonates, and turbidity.
- From data collected, students will be able to draw conclusions regarding water quality and human activities.
Part A: Sample Collection
Ten students should be selected from the classes to do the sampling. The collection is to be done at selected locations and noted on the sample bottles.
- A clean spring-fed stream (preferably limestone if available)
- Downstream from a cattle crossing (one without any improvements or structures added to prevent erosion and degradation of the stream bank).
- Downstream from a cattle crossing that has had fencing and structure installed to prevent erosion.
- A free flowing mountain stream (free stone).
- A slow-moving stream that has an obvious siltation problem and has been known to run dry during drought times.
Note: The dissolved oxygen tests as well as temperature readings should be done at stream side. Samples can be returned to the school and refrigerated for later testing.
Part B: In-Class Testing
Students should be divided into five groups in each class and given a kit and a water sample and directed to test the sample and record the results in the Data Chart. As a separate activity each lab group will be required to do research on the test that is being done and make an oral presentation to the class regarding the significance of the results. It is at this point that each group's results will be placed on a master class Data Chart on an overhead transparency.
Each group will complete the Data Chart and answer the questions.
Renn, Charles E. Investigating Water Problems: A Water Analysis Manual . Chestertown, Md.: LaMotte Chemical Products Company.
Wilson, James. Ground Water: A Non-Technical Guide . Philadelphia, Pa.: Academy of Natural Sciences of Philadelphia.
John W. Ford, State College Area School District