Can You Build a Model Wetland?
Wetlands are important for their ability to clean dirty water by filtering it. In this investigation, you are going to build a model of a wetland.
You will be given some materials, including a funnel. You will select materials for your filtering system, build the model and conduct 3 trials to get a container of dirty water as clean as possible. You need to make a diagram of your setup, record the materials you place in the funnel, and observe and record what happens when the dirty water is put through your filtering system.
45 to 60 minutes.
Instructional Support Downloads
Task Write Up
We used clear plastic soda bottles, cut in half. A few weeks before doing the investigation, you might want to begin collecting some two-liter bottles. An easy way to cut the bottles is to place each bottle inside a box lid (to hold it steady for an even cut) and turn it slowly while holding a sharp utility knife in place. The top will be the funnel; the bottom will be the container that the water drains into. (An excellent resource book for using plastic soda bottles for science investigations is Bottle Biology, by Paul Williams, Mrill Ingram and Amy Kelley, published by Kendall Hunt.)
- A Mason jar half-filled with soil and half-filled with water
- 3 coffee filters so the materials don’t wash out the hole in the soda bottle
- A stopwatch
- Sphagnum moss
- Rocks of different sizes
- Gravel, both fine and coarse
- Newspapers to cover the desks (large plastic garbage bags also work well for this)
- A plastic bucket to put all the materials in to give to students
Optional: You can also add leaves, food coloring, soap or oil, although, I did not. You could also add vinegar and check pH before and after filtering the water.
This investigation occurred during the middle of a unit on wetland ecosystems. Students had already researched, discussed and created a bulletin board with drawings, magazine cutouts or actual objects. They put the symbolic pictures/artifacts on the bulletin board, with a card that told how it related to the wetland ecosystem. For instance, a magazine cutout of a cradle showed that wetlands are used to protect the animals’ young, a sponge showed that wetlands soak up rainfall to prevent flooding, and a Monopoly house showed that animals use the wetlands for their homes. Students also played a tag game to show how dirt particles get caught by plant materials and soils and cleaner water emerges. Additionally, students viewed a Bill Nye video on wetlands.
This investigation demonstrates how a wetland works as a filtration system to clean dirty water. Students practice the ability to make a scientific diagram, observe the cause and effect of the filtering materials that are placed in filter, record data and draw conclusions based on data collected. Students use a model to develop their conceptual understanding about systems and interdependence in ecosystems.
I guide the students’ thinking, first by asking them how they get the water they drink. Most of them say they get water from the faucet. Next, I ask where the water from the faucet comes from and continue to question them until we have reviewed the water cycle. Then I’ll talk about a dirty puddle of water I saw on the way to school and ask how that dirty water can become clean so that the water is reused. That leads to explaining that this investigation will model how wetlands clean dirty water by filtering.
Students are divided into groups and given a bucket with a variety of natural materials to choose from. They construct a wetland and record the layers of materials they used to make it. When students are ready, I move about the room and pour dirty water into their filters. Using a stopwatch, they record how long it takes for the water to completely drain through the wetland filter. (If this takes longer than 10 minutes, I suggest they stop at 10 minutes.) They do this two more times, each time recording the layers of the filter. At the end of the experiment, they use their observations to write what they learned about how water is cleaned.
Students can discuss what happens if various pollutants make it through the water-filtering system and are present in water that we drink. This can be followed up by conducting tests of water samples from school and home water systems. Students can explore differences between hard and soft water (such as smell, sudsiness, etc.). Students could add vinegar to the water and check pH levels (before and after).
Invite the school custodian to talk about legal requirements for how the school monitors water quality. Have a hiker or military person explain how s/he can purify water while hiking on the trail.
Students can research and create a map of their state, showing where the wetlands can be found in their community and/or state. Students can research laws protecting wetlands in their regions. Students can visit local wetlands or local water filtration systems.
Students can write and illustrate a short story or poem about what it would be like to be one of the dirt particles as it travels from the jar, gets caught going through the filter and watches the water coming out clean. Students can write and illustrate the procedure for how water is filtered in a wetland or in a home water-filtering system.
Students can create a play about, or pantomime to music, what happens to soil particles and water when they travel through the filtering system.
Science, Technology, Society and the Environment
Influence of engineering, technology and science on society and the natural world.
Understandings about the Nature of Science (see appendix)
As the students put various layers in their funnels, ask them why they are putting the materials in that order.
- Can you explain your reason for putting materials in this order?
- Can you explain your reason for selecting these materials?
- What observations did you make during the first trial?
- What changes did you make from experiment one to two? from two to three?
- Is the water getting cleaner or dirtier? Why do you think that is happening? Where is the dirt going?
- Can you describe how the water is passing through the filter? Why is it taking so long for all the water to come through the filter?
- Is there more, less or the same amount of water coming through each time? How could you determine this?
- Does the order of the materials in the funnel affect how clean the water is? How could you determine this?
- How is this model like a real wetland? What have you learned about wetlands from your model?
- What have you learned about how water is cleaned?
- What would happen if the water was polluted? Would the wetland filter out all of the harmful pollutants?
(Unifying concepts/big ideas and science concepts to be assessed using the Science Exemplars Rubric under the criterion: Science Concepts and Related Content)
Science in Personal and Societal Perspectives – Populations, Resources and Environments; Personal Health: Students look for evidence and describe how human actions can cause changes in vegetation, ecosystems and/or entire landscapes. Students understand conservation and why it is needed.
Life Science – Populations and Ecosystems: Students see that human activities have an impact on natural systems and that changing human behaviors can lessen the impact on ecosystems.
Scientific Method: Students see that how a model works after changes are made to it may suggest how the real thing would work if the same thing were done to it. Students understand that choosing a useful model (not too simple/not too complex) to explore concepts encourages insightful and creative thinking in science, mathematics and engineering (models). Students observe and explain cause-effect relationships with some justification, using data and prior knowledge, when variables are controlled.
Mathematics: Students use precise measurements (time) and diagrams. Students collect, organize and analyze data appropriately.
Students could put the materials from finest to roughest or vice versa in the filter. Materials that are randomly thrown into the funnels may begin to settle into layers, rough to fine, naturally. As students complete the second and third trials, the water should become cleaner. The diagram should label materials used in the filtering system. Times should be recorded for each trial and conclusions stated, based on observations.
This student’s solution is incomplete. It appears that only one trial was completed, as one time is recorded. A diagram is included but lacks appropriate labels. The student does not record any materials used to clean the filter. There is no explanation of what was observed.
This student’s solution is lacking in detail, although the task is completed. Only one time is recorded, though three trials are conducted. The student includes three labeled drawings. It appears that materials were changed each time, but no changes made between experiments are recorded, other than the labeling. The student attempts to demonstrate some understanding of the water cycle in the explanation, but the explanations are confusing. Some results are summarized, but conclusions are not supported by data or reasoning using scientific or design concepts.
This student’s solution is lacking in detail, although the task is completed. Times are recorded for three trials, but they are not precise (all times are the same). The student includes three labeled drawings. It appears that materials were changed each time, but no changes made between experiments are recorded or explained. Some results are summarized, but conclusions are not supported by data or reasoning using scientific or design concepts.
This student’s solution is complete. Precise times are recorded for three trials. The student includes three labeled drawings. Changes are included in the student's diagrams that show how they rearranged the layers of materials they tested. Results are summarized and conclusions are supported by specific data from observations (e.g., “mostly gets cleaned by moss, then vermiculite cleans second most”). The explanation also discusses the water cycle.
This student’s solution is complete. Precise times are recorded for three trials. The student includes three labeled and detailed drawings. Materials were changed each time, and changes made between experiments are recorded and explained (e.g., “Moss between layers to absorb more”). Results are summarized, and conclusions are supported by specific data from observations (e.g., “vermiculite sucked up the water,” and “wetland moss cleaned the water the best”). There is an additional diagram of the water cycle, which is clearly labeled using appropriate scientific language.