Model a Watershed
Henry Street School for International Studies, Manhattan
Summer Research Program for Science Teachers
Grade Level: Middle School (Grades 6-8)
Time: 1-2 Class Periods
To introduce what a watershed (also called catchment basin by GLOBE protocols) is and how it works.
Students will construct a 3-dimensional model of a watershed. They will use the model to explore catchment basins, water pathways, and manipulate the model to illustrate how watersheds can change.
Students will be able to:
- define the concept of a catchment basin/watershed
- give examples of how their model relates to the real world- give examples of basic concepts of catchment basins and watersheds, such as, water runs downhill, hills make divides, low-lying areas create pooling, water quality is affected by what is upstream.
(GLOBE Hydrology Protocols align with the following concepts)
Earth and Space Science
Soils have properties of color, texture and composition; they support the growth of many kinds of plants.
Landforms are the result of destructive and constructive forces.
Soils consist of weathered rocks and decomposed organic matter.
Water circulates through the biosphere, lithosphere, atmosphere and hydrosphere (water cycle).
Water is a solvent.
Each element moves among different reservoirs (biosphere, lithosphere, atmosphere, hydrosphere).
Scientific Inquiry Abilities
Develop descriptions and explanations using evidence.
Communicate procedures and explanations.
Materials and Tools:
v Plastic Bin (larger bins are best, but any size will suffice)
v Miscellaneous objects that may be used to create the model infrastructure, such as buckets, bowls, rolls of paper towels, clay, wood blocks, rocks, etc.
v Plastic sheet or Plastic Wrap(2 x 2 meters)
v Spray bottle with water
v Red food coloring
v Permanent marker that will write on plastic or black electrical tape
v Topographic map
Gather materials/tools needed, separate so each group of students gets one watershed set-up. If a yard or outdoor space is available and conducting this lesson in that space is feasible, it may reduce the mess/clean-up.
How to Make the Model:
1. Designate work area- If working indoors, have students build their model in the plastic bins. If working outdoors, find an open space that students can wet with water.
2. You and your students gather the various objects to make the model, such as a plastic sheet, rocks, buckets, sponges, spray bottles with water, and food coloring.
3. Have the students arrange objects of various sizes inside the area. The tallest objects will become ‘mountains’. Shorter objects or buckets or bowls may become hills, lakes, or plains.
4. Cover the entire area and all of the objects with a sheet of plastic. Have the students use their hands to mold the plastic loosely around the covered objects. This is a model of a landscape with hills, valleys, and connections between them.
5. Have the students predict what will happen if it ‘rains’ on their model. Where will the water go? Will it go faster in some places? Will some places form pools? How do you know?
6. Use the spray bottle to ‘rain’ on the top of your highest ‘mountain’. Continue raining until you can see where streams, rivers, and lakes form.
7. Have the students choose a small pool on their model to be their “Hydrology Site.” Mark the site with a marker, stone, or other object.
8. Ask the students to make it rain by using the spray bottle. Ask the students questions. Where does the water come from that flows to your Hydrology Site? Where does water flow away from your Site? What things on the landscape determine what will be part of your basin? What determines the watershed? Explain to the students that the places where water hits and flows into their Hydrology Site are in the catchment basin for their site, the watershed is the basin boundary.
9. Ask students: Where would be a good place on their model to have their school? Where would you like your house to be? Have the students mark these places on the model.
10. Have students explore the consequences of changes in their catchment basin. Here are some things you can do:
a. What happens if you dam the stream that flows to your water site? (Use a sponge to create a dam).
b. What happens if you plant a forest above your site? (Use a large flat sponge for the forest - it will soak up water for a time just like soil and vegetation) What happens if you remove the forest?
c. What happens if someone builds an industry that causes pollution? (Use a small piece of sponge soaked in food color where your industry will be and watch the ‘pollution plume’ as it rains.)
d. What happens if someone decides to use water from your stream for irrigation or urban use? (Make ‘canals’ that take the water away from your stream to other places.)
National Science Standards:
Identify questions and concepts that guide scientific investigations.
Formulate and revise scientific explanations and models using logic and evidence.
Recognize and analyze alternative explanations and models.
Communicate and defend a scientific argument.
Design and conduct scientific investigations. Designing and conducting a scientific investigation requires introduction to the major concepts in the area being investigated, proper equipment, safety precautions, assistance with methodological problems, recommendations for the use of technologies, clarification of ideas that guide the inquiry, and scientific knowledge obtained from sources other than the actual investigation. The investigation may also require student clarification of the question, method, controls, and variables; student organization and display of data; student revision of methods and explanations; and a public presentation of the results with critical response from peers. Regardless of the scientific investigation performed, students must use evidence, apply logic, and construct an argument for their proposed explanations.