Lesson 2: What We Know About Our Watersheds

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This lesson builds students’ foundational understanding of watersheds by focusing on how water moves across land and how that movement connects places and communities. The central idea is simple but powerful: water flows downhill due to gravity, and the shape of the land determines where that water goes. This movement creates watersheds, which connect everything within them. What happens upstream in a watershed can affect water far downstream.

A watershed is the area of land where rain and runoff drain to a common body of water, such as a stream, lake, bay, or ocean.

Rather than presenting the definition of a watershed up front, students develop their understanding through observation and sensemaking. Using River Runner, they trace the path of water across real landscapes and look for patterns in how water moves. As they explore, students discover that water follows predictable downhill pathways, that small streams join to form larger rivers, and that water from many different locations can ultimately reach the same river, bay, or ocean. These observations help students recognize that watersheds are interconnected systems through which actions in one location can influence places far downstream.

Students then use Model My Watershed to investigate the relationship between land, water, and human activities. As they examine their schoolyard and surrounding community, they explore how different land covers—such as pavement, lawns, forests, and agricultural areas—influence runoff, infiltration, and evapotranspiration. By testing different land-use scenarios, students begin to see how human decisions affect the movement of water and the health of local watersheds.

Materials:

Materials you will need to gather:

Learning Objectives:

At the completion of this lesson, students will be able to:

  • Describe how gravity and topography determine the one-way, downhill movement of water across land. STEELS Standard(s): 3.4.6-8.C
  • Define a watershed as an area of land where all water drains to a common body of water, and identify and describe the local watershed using mapping tools. STEELS Standard(s): 3.4.6-8.C, 3.4.6-8.E
  • Use digital modeling tools such as River Runner and Model My Watershed to trace water pathways and analyze how smaller tributaries connect within larger watershed systems. STEELS Standard(s): 3.4.6-8.E, 3.5.6-8.Q
  • Analyze how different types of land cover (e.g., pavement, forest, agriculture) influence the movement of water and the health of watersheds. STEELS Standard(s): 3.3.6-8.N, 3.4.6-8.D
  • Evaluate how modifications to land cover or the addition of conservation practices can reduce runoff and improve infiltration within a local watershed. STEELS Standard(s): 3.3.6-8.N

Activities:

Driving Question: Where does the rain go after it falls on our schoolyard?

This activity introduces a simple but powerful idea: the rain that falls on the schoolyard does not stay there. Pulled by gravity, water flows downhill through streams and rivers, becoming part of larger watershed systems and connecting places along the way.

Begin by grounding students in a familiar location. Project a satellite image of your schoolyard (a screenshot from Google Maps works well) and pose the question: Where does our water go?

Students’ initial answers are often local—a puddle, storm drain, creek, or nearby river. Using River Runner, enter the school’s location and trace the pathway of water together. As the path unfolds, encourage students to notice patterns: Where is the water going? What bodies of water does it join? What direction is it moving?

Next, have students explore a new location, such as their home, a park, or another familiar place. As they compare the route water takes from different locations, they begin to recognize that water follows the shape of the land. Some locations drain quickly to major rivers, while others pass through multiple tributaries before reaching larger waterways.

If you choose to use the Where Do Our Rivers Flow? handout, students can use it to record and compare observations from their investigations.

Bring the class back together using the school pathway as a shared reference point. Shift the discussion from what happened to why it happened. Water follows elevation, not property lines or political boundaries. The shape of the land determines where water flows and where it collects. This is the moment to introduce the term watershed—the area of land where all water drains to a common body of water.

To close the activity, show the short video What is a Watershed? And Why You Should Care. Encourage students to connect what they observed in River Runner to the larger ideas that topography drives water movement and that human activities can influence water quality throughout a watershed.

In this activity, students use Model My Watershed to investigate the watershed that contains their school and explore the land uses that shape it. Building on Activity 1, students move from tracing where water flows to examining the landscape through which that water travels.

Using the Exploring Your Local Watershed with Model My Watershed handout, students begin by locating their school and identifying the HUC-12 watershed in which it is located. As they examine the watershed boundary, they develop a more concrete understanding of a watershed as an area of land that drains to a common body of water.

Next, students investigate land cover within their watershed using data contained in Model My Watershed. Using land use data, they identify the dominant land types and consider how forests, agricultural areas, developed land, and other landscape features may influence the movement of water across the landscape.

Students then shift their focus to the schoolyard. Using the Draw Area tool, they outline the school property and analyze the different land covers present. Comparing the schoolyard to the larger watershed helps students recognize that different parts of a watershed have different land-use patterns and surface characteristics.

To conclude the activity, bring the class together to discuss patterns they observed. How does the land cover of the schoolyard compare to that of the larger watershed? What types of surfaces dominate each area? How might these differences influence the movement of water when it rains? This discussion helps students connect land use, water movement, and watershed processes while preparing them for later lessons focused on stormwater and water quality.

Adaptations & Extensions:

If students need a more hands-on way to visualize how water moves across land, Building a model of a watershed provides a simple and effective extension. In this activity, students crumple a sheet of paper to create a landscape of high and low points, then use markers to create a town and spray water to see how rain would move across the landscape. As they observe where water collects and how it travels downhill, the idea of ridgelines and watershed boundaries becomes more visible. This is a good option if students are struggling to connect the digital models to physical landforms, or if you want to reinforce the idea that the shape of the land determines where water flows.

Assessment:

Use the following questions to show what you’ve learned about watersheds:

  • How do our actions affect others?

    Imagine someone pours oil down a storm drain near your school. Using what you know about watersheds and downhill flow, explain how that oil could move and who might be affected.

  • Using evidence from a model or map.

    Choose one place you explored using River Runner or Model My Watershed. Describe how water moves from that location and explain how land cover along the way could affect water quality downstream.