Billion Oyster Project

Watersheds Part 3 - Build a Watershed Model


New York’s Urban Ecosystem Lessons



Class Periods




Subject Areas


Students will build a model of a watershed using a variety of materials in order to study the effects of runoff.


  • Observe how water flows over a watershed model with varied surfaces

  • Determine the effect pollutants have on the local watershed

Materials and Resources


  • Large aluminum pan or paint tray
  • Several pieces of paper (newspaper or scrap paper)
  • Tape
  • Aluminum foil, plastic wrap, butcher paper, and/or cloth
  • Small model pieces to represent buildings, cars, trees, etc. (optional)
  • Pieces of sponges
  • Variety of colored powders or dyes (cocoa, fruit drinks, food coloring, etc.)
  • Little pieces of plastic wrappers or similar plastic
  • Spray Bottle
  • Water

Before you get started

Tips for Teachers

You can get slightly different effects on your watershed model depending on which material you choose as the ground surface. The water will run more quickly down aluminum foil or plastic wrap and will absorb more into butcher paper or cloth. In this lesson students make their own watershed models. You can also buy watershed and sewershed models. Watershed models are expensive and bulky to store, but can last many years if well cared for. Both homemade and purchased models work best with students in small groups. Consider having students stand, instead of sit, around the models so they can easily see all aspects of the model. If you use a model as a demo in front of the whole class take extra care to make sure all students can see the model.





Instruction Plan


  1. Students get into small groups.

  2. Each group gets aluminum/paint tray, paper, tape, aluminum foil/plastic wrap, sponge pieces and small model pieces.

  3. Crumple several pieces of paper into balls and tape them down in the tray to create the foundation of a hilly topography.


  1. Note: Consider mimicking one of the topographic maps you looked at in the previous lesson, “Watersheds Day 2 - Paper Watersheds.”

  2. Cover the paper balls with more than one type of surface type (e.g. aluminum foil and cloth) and tape down.


  1. Place and tape down a couple pieces of sponges throughout the watershed.

  2. Tape small model pieces on the watershed if desired.

  3. Explore the different parts of the model (e.g. hills, valley, river, estuary).

  4. Spray the model with water using the spray bottle and discuss results.  Ask students to share their predictions and the results they observed.

  5. Name and then place different pollutants (i.e. powders, food coloring and plastics) on the model.

  6. Think about which materials could represent which kinds of pollutants (i.e. oil, litter, dog poop, etc.)

  7. Spray the now-polluted model with water and discuss results.

  8. Use the following discussion questions throughout the activity or in a worksheet.

    • Describe what the watershed model looks like.  What features does it include?

    • What features are similar to something you know or have seen in outdoors?

    • Sketch your watershed model.  Add to your sketch throughout the activity.

    • What do you predict will happen when you spray water on your watershed model?

    • What happened when you sprayed water on your watershed model? Record your observations in words and/or diagrams.

    • Which direction did the water flow?  What factors influence the direction of the water flow?

    • Where was the water absorbed?  Explain why it was absorbed there.

    • Where did the water collect?  Explain why it collected there.

    • Name some different types of pollutants you might find in the watershed? (Think about what you see on the street outside your school.)

    • What do you predict will happen when you spray water over the pollutants on your watershed model?

    • What happened to the pollutants when you sprayed water over them?

    • What specifically could YOU do to reduce the amount of pollutants in the watershed?

    • What are some larger scale actions that could reduce the amount of pollutants affecting the watershed?

    • What types of interventions could be designed and built that would help prevent pollutants in the watershed from entering the nearest waterbody?