Lesson 4: Runoff and Infiltration on Your Schoolyard

Download Lesson 4 Professional Development

Water moves across the landscape, carrying sediment and pollutants into streams, rivers, and eventually into larger bodies of fresh water. As a reminder, fresh water is natural water with very low concentrations of dissolved salt, such as the water found in lakes, rivers, wetlands, and groundwater. Human activities—like construction, agriculture, and urban development—can change how water moves, often increasing runoff and erosion. In this lesson, students will investigate how water flows through their own schoolyard and how it interacts with different surfaces. They’ll come away with a clear understanding of runoff (water that flows across the surface) and infiltration (water that soaks into the ground).

As water moves across hard or compacted surfaces, it picks up pollutants that can harm nearby waterways and ecosystems. Watershed conservation efforts aim to reduce runoff and prevent this pollution from reaching streams and rivers. One key strategy is to increase infiltration—helping water soak into the ground where it lands, rather than letting it run across the surface.

This hands-on activity gives students the chance to observe how different surfaces respond when water is poured on them, but it’s also a chance to focus on local phenomena. For many, it will be the first time they examine their schoolyard with a critical eye: What surfaces are there, and where does the water go when it rains?

Materials:

Materials you will need to gather:

  • Lesson Slides
  • Activity 1: Outline of your schoolyard/school property (created by you, the teacher using Google Maps,) 1 per student
  • Activity 1: Clipboards and pencils/colored pencils/crayons/markers (for recording observations outdoors), 1 per student
  • Activity 1: 5 gallons of water in reused milk jugs or a bucket (the milk jugs are easier to carry!)

Lesson Preparation: Before the lesson, prepare a blackline master map of the schoolyard—an outline of your school property using Google Maps. Print copies for students to use as their Runoff Observation Sheet, where they will record their data during the outdoor investigation.

Learning Objectives:

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

  • Observe and document how water moves across different land surfaces. STEELS Standard(s): 3.4.6-8.C, 3.3.6-8.H
  • Identify surfaces that will cause runoff and those that will cause infiltration based on permeability. STEELS Standard(s): 3.4.6-8.E
  • Map their schoolyard by hand, indicating different land covers. STEELS Standard(s): 3.3.6-8.E, 3.4.6-8.H

Activities:

Water moves downhill across the land in different ways depending on the surface it encounters. Some areas allow water to soak in, while others create runoff that flows toward drains, ditches, or low-lying areas. In this activity, students will investigate their schoolyard to track the movement of rainwater and identify patterns in runoff, infiltration, and possible sources of pollution.

Before heading outside, ask students where they think rainwater drains on the school grounds. Many may not know. Despite spending time outside daily, students often don’t notice storm drains, retention areas, or even how the ground is shaped to guide water. By grounding the concepts of runoff and infiltration in their own environment, students will better relate to the content, carry that understanding with them beyond the lesson, and begin laying the foundation for the unit’s final action plan.

Take students outside and ask them to think about where they have seen water collect during a rainstorm. Is there a section of the sidewalk or parking lot that always has a puddle? Do parts of the sports fields become soggy after a storm? Have they noticed water flowing toward a storm drain or ditch?

After a brief discussion, distribute the Runoff Observation Maps. Explain that students will use the maps to identify different land surfaces, record areas of runoff and infiltration, trace the direction water moves, and document potential sources of pollution across the schoolyard.

As you move through the schoolyard, visit a variety of locations, such as:

  • Impervious surfaces – sidewalks, parking lots, roads
  • Pervious surfaces – lawns, gardens, athletic fields
  • Drainage features – storm drains, gutters, ditches
  • Conservation features – rain gardens, bioswales, planted buffer zones

At each location, ask students to:

  • Observe the surface. Is it pavement, concrete, gravel, grass, mulch, or another material?
  • Predict what will happen to water. Will the water soak into the ground (infiltration), collect in puddles, or flow across the surface (runoff)?
  • Test the prediction. Pour a small amount of water onto the surface and observe what happens.
  • Record observations on the map. Note whether the area promotes runoff or infiltration, the direction water travels, and any signs of puddling, erosion, storm drains, litter, or other potential sources of pollution.

Students should use colors, patterns, and symbols to make their observations visible on the map. For example, blue arrows can show runoff pathways, green shading can indicate areas where water infiltrates, and symbols can identify drains, puddles, erosion, or pollution sources.

Making Sense of the Observations

Return to the classroom and bring students together to analyze their maps. Which areas produced the most runoff? Were there any surprises? If conservation features were present (e.g. rain gardens, bioswales, vegetative infiltration basins), did they seem to help? Encourage students to connect their observations to larger watershed issues. If rainwater can’t soak into the ground, where does it go? How might pollutants like trash, sediments, or chemicals travel with it?

Wrap up by asking: If you could design a more sustainable schoolyard, what changes would you make? Their discoveries will set the stage for the next lesson, where they will build and test their own watershed models to explore erosion and conservation strategies.

Adaptations & Extensions:

Infiltrometers

To add a quantitative component to the Schoolyard Runoff Tour, replace the simple “pour and observe” test with an infiltration tube, or infiltrometer. At each location students visit, place the tube firmly on the ground, pour 250 mL of water into the tube, and use a stopwatch to measure how long it takes for the water to infiltrate. Students can record infiltration times directly on their Runoff Observation Maps and compare results across the different surfaces they investigate.

The infiltrometer allows students to move beyond simply identifying areas of runoff and infiltration to measuring how quickly water enters the ground. Students often discover that areas that appear similar—such as a lawn and a meadow—can have very different infiltration rates.

Teacher Tip: Infiltrometers can be purchased or made from clear plastic tubes approximately 12 inches long and 2 inches in diameter. If creating a watertight seal is difficult, use clay, playdough, foam, or a rubber gasket around the bottom edge of the tube.

Assessment:

  • Exit Ticket

    After exploring your schoolyard, choose one spot where you saw water behave in an interesting way. Describe what happened when water was poured there. Did it soak in or run off? Why do you think that happened?

  • Follow-up Question

    If we wanted to help more rainwater soak into the ground at our school, what’s one change we could make to a spot that did not allow water to infiltrate well?