Summary: Students collaboratively build models of watersheds by placing a large piece of butcher paper over various sized objects in a large pan. As students spray their model watersheds with water, they observe and mark on their map the movement and pooling representing rivers, lakes and ponds.
- 100 minutes (two 50-minute class periods)
- Several tall objects and short objects (2 or 3 of each per model)
- White butcher paper (3’ x 4’ sheets)
- Large waterproof tin trays
- Transparency film
- Small spray bottles with water
- Food coloring or tempra paint
Educators should construct and test the watershed model prior to class to become familiar with the project and to ensure that materials work appropriately.
Part 1 – Preliminary Discussion
Ask students key questions:
- Does anyone know what causes a river to flow in a certain direction or how its shape may be altered?
- Do you think the land around our rivers affects the quality of the water?
- Introduce the term watershed. One way to introduce this term is to ask students to separate the word into “water” and “shed” (to pour or cause to pour off; to emit) and discuss what each word means. Ask students what “sheds” water? (The land around a river.)
- Inform the class that they will be learning about watersheds using a model, which is a simplified representation of a natural phenomenon. Models help scientists represent their current understanding of natural phenomena as well as construct new understanding.
Part 2 – Preparing for the Build
- Preview the materials and demonstrate how to build the watershed model.
- Connect the watershed model to the real world.
- What might be the purpose of this watershed model? Have students describe what the pieces of the model represent.
- Paper = land; Spray bottle = precipitation.
Have students form groups:
- Hand out Part 1 of the student worksheet: What is a Watershed?
- Assign roles to group members: object placer, paper placer, taper, watershed transparency map creator, and/or sprayer. (Assigning roles is one strategy to facilitate small group interaction until students become adept at working together.)
- Remind students that they are all responsible for creating individual watershed maps, filling out their predictions, observations and explanations, and taking notes on the concepts they identify.
- Distribute materials.
NOTE: Do not have the students get water bottles yet!
Part 3 – Build a Watershed Model
- Review set-up procedure with students. (Steps 1-4 on the work sheet.)
- Monitor students as they build their watershed models.
- Create an elevation map.
- Describe the procedure for making an elevation map. (Steps 5-6 on the work sheet.) Students will mark high areas with “H” and low areas with “L” on both their model and on a separate transparency.
- Monitor students as they create maps and have groups raise their hands when maps are completed.
- Predict water flow. Review steps for making predictions. (Step 7 on the work sheet.)
- Monitor students as they make predictions and explanations on their worksheets or in journals, about how water will flow over their watershed model.
- Have groups raise hands when predictions are completed.
- Observe and test models. Inform the students that they are now ready to test their models and make observations. Remind them to keep detailed notes of their observations: they will use their observations to help explain their models.
- Give each group a spray bottle. Students will use spray bottles to test their watershed model.
- Monitor groups as students make observations. Return materials.
Part 4 – Discuss the Results
Have a few groups share their transparency elevation maps using an overhead projector.
- Ask the class to answer the following questions:
- How did the water flow over the surface of the land? What patterns did you observe?
- How did the water accumulate? Where did the water accumulate?
- In what direction did the water flow? What caused the water to flow that way?
Now that the students have built a model (a representation) of a watershed, review key concepts:
- What is a model? What is the purpose of a model?
- Have students describe what the pieces of the model represent.
- Previously introduced watershed model parts:
- Paper = land
- Spray = precipitation
- Newly introduced watershed model parts:
- Branching pattern of the water flow (smaller rivers leading into larger rivers) = a river system
- Wet portions of the paper = absorption of water by land
- Flow of water over the paper = runoff
- Change in elevations on land = slope
- Entire model = watershed
- Discuss how using the models can help them investigate their river.
- Remind students that they observed the results from testing a model. To enhance understanding, students may wish to take notes, create a classroom chart, or make entries in a journal.
- The following key concepts should emerge:
- A watershed is an area of land that drains into a river system.
- Water moves from areas of high elevation to areas of lower elevation, following the slope in land.
- The flow of water occurs in a branching pattern in streams and rivers (i.e. stream system). Branches may combine to form lakes or larger rivers.
- Effects of precipitation — i.e. rain and snow might be absorbed by the ground, or might form runoff that feeds into rivers.
- Ask student to describe the direction of water flow within the watershed. Prompt students by asking them how elevation affects the flow of water. A common misconception is that all rivers flow south.
- Be sure to emphasize that rivers flow in all directions depending on the change in elevation in the watershed. (Use Michigan as an example.)
- Ask students to draw the flow of water on their own maps.
- Have students come to the front of the room and draw the flow of water for a specific part of the map. Students should explain why the water flows as they predict.
- Repeat the above step until all map parts are explained.
Predict, Observe, Explain
The cycle of predicting, observing and explaining is a strategy to support students in constructing understanding. Emphasize the reasons that predictions, observations and explanations are made. Encourage students to question each other, elaborate on their ideas, and share their thinking with other groups.
The purpose of sharing ideas is to determine that students understand main ideas. Often, however, there is not enough time for all groups to present their observations. Consider having a few groups present ideas, while others participate in the discussions by stating whether or not they observed the same patterns.
Assessment & Standards
See separate document: Lesson Assessment, State of Michigan Content Expectations and National Benchmarks (PDF)