If students are not already familiar with the equipment, you will want to do a practice run in the classroom with water samples from the stream. This will allow students to practice using the chemical test kits and give everyone time to think through their hypotheses. You should also decide whether you want to include macroinvertebrates in your survey. Use the collection techniques in the lesson titled “Aquatic Ecosystem Exploration” in the “Ecosystems in Action: Cycling of Matter & Energy” unit or in “Land Use & Water Quality” in the “The Hudson Valley: A Social-Ecological System” unit.
- Set up a rain gauge outside the classroom.
- Designate a student to collect data routinely from the rain gauge.
- Ask: Why do we collect precipitation data? How much rain do you expect in the next week? The next month? How much rain is associated with a ‘storm event’? How much rain would be needed in order to change the local stream? What impact would a storm event have on a local stream? In order to understand how a storm event affects a stream, what do you have to know?
- Together with students, define baseline data. Baseline data refers to data that is collected before a study begins, to provide comparison with later assessments. Ideally, students should go out two or three times to get enough information for their baseline data. Review safety procedures for outdoor work.
- In groups, students will test the water quality and make observations about the physical characteristics of the stream. Based on the size of your class, you will want to assign groups different variables to test.
- Decide as a class how you want to sample the stream; do you want to split groups up to sample different areas, or will everyone work in one area?
- Visit the stream and allow the students to gather their respective data for about 20 minutes (or when all groups seem finished with the survey).
- All students should do a detailed site drawing.
Discuss student findings after you return to the classroom. What did students notice? If students collected macroinvertebrates, discuss the connections between the organisms that live in/near stream with the physical characteristics of that stream. To see the average precipitation for a given time period in your region or to see the current observed precipitation so far, visit: http://1.usa.gov/19GflaV (http://water.weather.gov/precip/) You can choose the time period for which you want data, whether you want ‘Observed’ or ‘Normal’ values, and what state or region you’d like to observe. The bitly link defaults to NY state observed values.
Storm Event Monitoring:
- After students have discussed the initial surveys, allow them time in their groups to develop hypotheses. How will each stream characteristic that they observed change (or not change) during a storm event?
- Return to the site after a storm event and complete the survey again comparing it to the baseline data.
Depending on the length of time after the storm event, students should notice physical changes as well as some chemical changes. Since most streams return relatively quickly to pre-storm chemistry, these parameters will be the most difficult to measure. If possible, return to the stream a few more times to collect more data. Another way to encourage students to design their tests is to figure out how long it takes a stream to return to the pre-storm chemistry levels. Again, if possible, return to the stream a few more times to collect more data. Encourage students to determine the validity of their data based on the limitations of a school setting (i.e. limited class time, inability to measure during the storm). While students are writing up their lab reports, they are asked to think about the difference between a ‘bend’ and a ‘break’ in an ecosystem (a temporary vs a permanent change). If this is a difficult concept for students, spend some time discussing what this might mean for a stream versus a larger ecosystem such as a river. Ask students to classify different environmental problems as ‘bends’ or ‘breaks’.
Students can create a presentation on their research for community members or other audiences within the school.
Assess student understanding from their completed hypotheses, data sheets, and lab report.