Water Quality Investigation
Students will investigate the factors that contribute to a healthy watershed using water samples from the pond, stream, marsh, bog, estuary, or ocean. Students will test pH, dissolved oxygen (DO), Turbidity, and temperature. Using these different forms of data as evidence, as well as observation, students will make a conclusion about the health of the local watershed. After the conclusion, students will then brainstorm ways in which they could improve the water quality, which could then evolve into a service learning project.
What do you remember about watersheds? A watershed is the area of land that drains into a particular body of water, such as a river, pond, lake, or ocean or even a small creek in your neighborhood. When the rain falls on your school’s roof and on the playground, where does it go? Do you know what body of water it eventually drains into? Does anyone know what watershed your school is in? What about here at IslandWood? We have our own mini watershed right here at IslandWood! Explain that water flows with gravity, downward. Depending on the surface, some water will percolate into porous earth surfaces, while on other surfaces, like pavement, water will continue to flow picking up other substrates and pollutants, this is called run-off.
At the edge of the pond or the marsh, explain that we will be trying to determine the health of the water using some of the same methods/tests used by scientists. Ask if anyone has ever been to a place that was really unhealthy. How did they notice? What senses can you use immediately to give you information about a place? There are many ways of “knowing” a place and all sorts of ways to gather information. Today we’re going to use both our senses and some methods/tests used by scientist to explore this place. Now, do you remember what most living things need to survive (food, shelter, LAWS, etc)? By looking around, do you see these things? List as many as possible with qualifying descriptions. What is your impression of the health of this place? Why do you think that?
- Let students predict which way water flows in the system by exploring and gathering evidence
- Start students at the watershed model behind the Learning Studios, let them make predictions about water flow using chalk arrows on the model and then add water to their arrows to check.
- Tell them theJourney of a Water Drop Story
- Play the Water Cycle game
- Look at the IslandWood watershed map
- Sing Water Cycle Boogie
Setting the tone
- We’re going to begin by making some basic observations about the creek using four of our five scientific tools, also known as our five senses. This will help us come up with our predictions, or educated guesses. First, with your voices off and your eyes closed, we’re going listen for 20 silent seconds. Ask students to share what they heard.
- Second, let’s turn out voices off and close our eyes once again, all together let’s take a deep breath in through your nose. Ask students to describe what they smelled.
- Finally, with voices off, take a second to look around. Through the next hour, I want you to notice your surroundings. How can you describe the color of the water? What sorts of vegetation is around this creek? Can you notice any signs of human impact, either positive or negative? Can you notice any signs of pollution? Can you see any erosion? I also want you to gently touch the environment around you. How cold does the water feel? What does the texture of the soil feel like? [this is a barrage of questions- please write them down for students to refer to]
- Using these observations, everyone get out your thumb-o-meter to make a prediction about the health of this creek. Explain how the thumb-o-meter works. Take 3 seconds to calibrate…3…2…1! Ask a couple students to explain their reasoning behind their guesses. Now here comes the most exciting part of the investigation, data collection!
- What is the relationship between location and pH (or temperature, DO, turbidity)?
- What is the relationship between ...
The Investigation Procedure (student centered)
- Divide the students into groups or stations to do the following tests depending on student/adult ratio. Stations are useful because they ensure many trials for each experiment and the more data the more accurate the conclusion. You can also divide students into groups based on test, and then they are responsible for knowing how to do their one test at several locations. Possible groups:
- 1-2 students- temperature
- 1-3 students- water turbidity
- 1-3 students- Dissolved Oxygen
- 1-3 students- pH
- 1-2 students- data collection
- Either demonstrate to the group how to use the tools are ask them to read the directions in the book that comes with the kit. It is one short page of directions. Students can record data on page 20 (water quality comparisons)
- Temperature: a measurement of how much heat is in a substance.
- First, we’ll take an air temperature. Make sure to allow the thermometer to calibrate for at least 30 seconds. Record the data.
- Repeat in the water. If the body of water is deep enough, take a surface temperature reading and a deeper temperature reading. Record the data.
- Remind students to make sure the thermometer is fully submerged in the water and to wait for 30 seconds after submersion.
- Show students the marks or knots on the string for the two different water depths to ensure data is consistent.
- Turbidity: the cloudiness of a fluid.
- Measuring turbidity allows us to quantify how much material is suspended or floating in the water. The unit is JTU.
- For this measurement, Fill the water quality kit bucket with water up to the fill line. Look for the Secchi disk at the bottom of the inside of the bucket and compare it to the results sheet. Record the data.
- pH: a number describing the acidity or alkalinity (how basic) of a solution.
- Ask for examples of things that are both acidic and basic, and explain that most organisms need a neutral pH in order to survive.
- Using the directions in the pH kits, follow instructions & record the data.
- Dissolved Oxygen (DO): the amount of oxygen gas dissolved in water (ppm). The more oxygen present in the water, the easier it is for most aquatic organisms to breathe.
- Using the directions in the DO kits, follow instructions & record the data.
- Temperature: a measurement of how much heat is in a substance.
- If one of the groups finishes before the other group, ask students to continue to make observations around the creek- color of the creek, smell of the creek, vegetation, erosion, pollution, etc.
- Macroinvertebrate Collection: This can be added on the the chemical investigation of the water if you want to analyze both chemical and biological aspects of the water. If time allows, this can illustrate to students the importance of several perspectives and factors related to determining the health of the watershed since no single test can determine the health.
Data Analysis and Conclusion
- Ask students to sit in table groups with students who had the same ‘job’ as them (1 temperature group, 1 turbidity group, 1 pH group, 1 dissolved oxygen group, & 1 data collection/ observation group). Within each group, students should find the average of the 3 pieces of data collected.
- Ask students to write a conclusion statement that translates the data into words:
- There is higher pH at (location) with an average of (average #) pH.
- There is lower DO at (location) with an average of (average #) DO.
- There is higher turbidity at (location) compared to (location) by an average of (differences between the averages) turbidity.
- I think there is a higher temperature at (location) because there was an average of (average #) temperature.
- I think there is a lower temperature at (location) because there was an average of (average #) temperature.
- If you gathered information about macros: as a class, make a conclusion for your macroinvertebrate data. Explain to students the meaning of each category.
- Group 1, Tolerant, these organisms are tolerant to pollution and can survive in any water quality, from very clear water to very polluted water. The presence of these organisms doesn't mean the water is unhealthy, but it can be a poor sign of health if these are the only organisms present.
- Group 2, Semi-tolerant, these organisms are semi-tolerant to pollution and can survive in semi-polluted water, as well as clean water.
- Group 3, intolerant, these organisms are intolerant (not tolerant) to pollution and will die in polluted or semi-polluted water. Thus, presence of organisms in group 3 confirms that your water is clean.
- Ask each student pair/ trio to share the data collected for each category, and for other students to record this data in their notebooks. As a class, find the average for each group.
Communication & Next Steps
- After finding the average & writing the conclusion, students can discuss in their groups what this data says about the water quality or water health.
- Give students about 5 minutes to prepare a short 1-2 minute presentation to share with the class. The presentation should include
- a brief procedure on how they collected their data
- the data they collected
- their conclusions: what does this mean for the health of the watershed? Ask students to ensure that all students in the group have a chance to talk and share their opinions.
- While students are discussing, visit each group to assist students
- While students are presenting, instruct the other students to fill in their data charts using this information. Encourage students to raise their hands for questions at the end of each presentation.
- Ask students to brainstorm other ways they could investigate to determine watershed health (such as presence of invasive species, evidence of pollution or run-off, erosion, deposition, evidence of animal habitats around the water, litter/ graffiti, etc). And
- Second, figure out what sorts of things they could do to improve the health of the watershed (i.e. invasive species removal, planting native plants to prevent erosion & deposition, pick up litter & install signs, trash cans & recycling bins, persuasive writing to local government or businesses to discourage pesticide use, chemicals during car washes, etc.).
- Create a plan of action!
- the debrief discussion of this activity may be the most important part of the lesson- make sure students have a chance to walk through the results and make sense of the data so they can draw some conclusions about the watershed.
- Why do scientists collect information like this?
- We did all this collecting, investigating and identifying to learn about the health of our watershed. What have we learned so far?
- Scientists have developed charts and systems for figuring out what conditions are best for certain animals, including [index.php?title=Macro_invertebrates macros] and salmon. We can use these tests to find out- even if this place looks healthy, this tests give us more information that will help us determine how healthy it is. Let’s take a look at our results in our journals and see what we think. What kind of results did we get? What would happen if we did these tests at another time of year? What if the weather was different than it is today, would that affect our tests?
- What new questions do you have?
- Is there a body of water near your home where you can do these tests?
- Certain tests such as pH and turbidity can be done as many times as needed. The dissolved oxygen test can only be done a maximum of 2-3 trials due to the cost of the materials used, but many students can be involved in each trial.
- Some of the tests will involve instruments and chemicals and it’s important we understand how to work with this stuff before we start using it, otherwise we could skew the results. Scientists have to be very careful when they perform experiments and gather data; otherwise the data they gather will be meaningless. This is a good place to point out why we have written procedures (for replicability). Every student will be responsible for quality control in this way.
- Water Macro Investigation
- Compare data with another group
Relevant Journal Pages:
- Investigation planning and charts, pgs. 8-12
- "Water Quality Comparisons", pgs. 20-21
- "Aquatic Macroinvertebrates", pg. 16