Billion Oyster Project

Can you Out-Filter an Oyster?


Oysters & Organisms Lessons



Class Periods




Subject Areas

Science, Math


Students will work in small groups to build a “filter” out of household materials and compete against other groups to see who can do the best job filtering the special mixture of “harbor estuary water” that the teacher creates for them.


  1. Identify some of the common pollutants found in the New York Harbor estuary.
  2. Plan, diagram and design a filter that removes certain “pollutants” from the water
  3. Compare the functioning of their filter to the functioning of an oyster

Materials and Resources


  • filter Kit Supplies aluminum trays (approx 13”x9”) - 2 per group
  • colander - 1 per group
  • measuring cup - 1 per group
  • 250 mL plastic beaker - 1 per group
  • household materials for building filter
    • napkins
    • paper towels
    • sponges
    • coffee filters
    • gauze
    • cotton balls
    • cotton swabs
    • straws
    • masking tape
  • household materials for the “New York Harbor Estuary Solution"
    • salt
    • potting soil (with styrofoam pieces)
    • cooking oil
    • dish soap
    • Chocolate Rice Krispy Treats
    • food coloring

Before you get started

Tips for Teachers

  • “New York Harbor Estuary Solution” recipe (amounts are an approximate guide)
    • 1 ½ cups water
    • ¼ tsp salt
    • 1 Tbs potting soil
    • 1 tsp cooking oil
    • 1 tsp dish soap
    • 1 tsp Cocoa Krispies
    • 1-2 drops food coloring
  • Prepare all the “New York Harbor Estuary Solutions” in advance except one to do as a demo in front of the class.
  • Prepare all Filter Kits in advance.
  • This activity is designed to have the students design, build and test the filter only once. If you have the time, consider allowing the students to revise their design and build a second filter based on what they learned from the first test.


According to NOAA and the Chesapeake Bay Foundation, a single Eastern Oyster (crassostrea virginica) can filter up to 50 gallons of water a day.  Oysters are filter feeders, which means they eat by pumping large volumes of water through their body. In order to eat, oysters open their shells slightly, exposing the little hairlike structures on their gills, called cilia.  The oyster moves these cilia in a wavelike motion creating a localized water current, thereby drawing the water inward and over the gills.  This process both ventilates the oysters gills for respiration and captures particles that the oyster will eat. The exact mechanism of particle capture is a complex one, and is accomplished in two different ways: the hydrodynamic mechanism draws in particles through the movement of water; and the mucociliary mechanism uses cilia structures and mucous to capture particles. Particles removed from suspension by these two mechanisms are transported along the gills to the labial palps.

The mechanism by which oysters and other bivalves differentiate between different types of particles is not well understood. The labial palps are able to sort and select individual particles, moving the algae, food and nutrients towards the esophagus, while all other non-nutritious particles become pseudofeces and expelled before going into the digestive system.  

Most of the particles filtered by oysters are about 1-10 microns in diameter, approximately the same size as the single-celled phytoplankton (algae) that make up most of their diet. Some of the food particles are also ejected as pseudofeces without passing through the gut, because oysters need to ventilate their gills for more time than they need to feed.

Instruction Plan


  1. Show the students one of the Oyster Filtration Youtube videos listed under Teacher Resources. Discuss as fits the needs of your class.
  2. Separate students into small groups.
  3. Hand out a “Can You Out-Filter an Oyster?” worksheet to each student.
  4. Review activity directions/rules (you may want to add more of these rules to the “Directions” section of the worksheet:
  5. Use as few or as many materials as you choose.
  6. Materials may be altered (e.g. rip the sponge in half).
  7. The teacher will pour the estuary solution through each filter so the pouring is consistent and fair from group to group.
  8. Each filter is allowed to process the estuary solution for exactly one minute.
  9. You may not touch your filter in any way during the filtering (e.g. You may not press on the sponge to squeeze out the water).
  10. Use the colander as the foundation of your filter. Do not alter the colander in any way.
  11. The colander will sit in one aluminum tray, which will catch the water coming out of the filter. You will transfer the colander to the second aluminum tray at the end of one minute.  The liquid in the first aluminum tray will be poured into the 250mL beaker. Do not alter the trays in any way. 
  12. Create a “New York Harbor Estuary Solution” in front of the class.  Add ingredients one by one, soliciting from the class what happens to the ingredient in the water (dissolve, sink, suspend, float, etc.) and what the ingredient represents in real life.


  1. Hand out one Filter Kit to each group and review the included materials.
  2. Give students about 15 minutes to design and build their filter.  Consider requiring groups to draw a preliminary sketch of their filter for approval before they are permitted to build it.  
  3. When a group finishes their filter make sure it is placed in one of the aluminum trays.
  4. Pour the Estuary Solution through the filter slowly and evenly making a spiral motion around the bottom of the colander.  Let the water drain through for exactly one minute.
  5. When one minute is up transfer the colander to the second aluminum tray (as it will continue to drip) and pour the contents of the first tray into the 250mL beaker.
  6. Put a piece of masking tape on the side of the beaker and write the filter name.
  7. Students begin to work on “Part IV: Analyzing Your Filter” of the worksheet.


Once all filters have been tested bring all the beakers up to the font of the classroom and facilitate a discussion comparing and contrasting the results.  Solicit from students which materials they chose to use and how they used them.  Solicit from students what worked well and what they would do differently next time.  


Students calculate how their filter compares to an oyster (#7 and #8 on worksheet).


Students work either individually or in their groups complete the “Machine vs Nature” section of the worksheet.


CCLS - ELA Science & Technical Subjects

    • Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.

CCLS - Mathematics

    • Use ratio reasoning to convert measurement units; manipulate and transform units appropriately when multiplying or dividing quantities.

NGSS - Cross-Cutting Concepts

  • Energy and Matter

    • Within a natural or designed system, the transfer of energy drives the motion and/or cycling of matter.

NGSS - Disciplinary Core Ideas

  • ETS1.B: Developing Possible Solutions

    • A solution needs to be tested, and then modified on the basis of the test results in order to improve it. There are systematic processes for evaluating solutions with respect to how well they meet criteria and constraints of a problem. (secondary)
  • LS1.C: Organization for Matter and Energy Flow in Organisms

    • Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy.

NGSS - Science and Engineering Practices

  • Constructing Explanations and Designing Solutions

    • Apply scientific ideas or principles to design, construct, and test a design of an object, tool, process or system.

NYC Science Scope & Sequence - Units

  • Grade 6, Unit 3

    • Diversity of Life
  • Grade 6, Unit 4

    • Interdependence
  • Grade 8, Unit 4

    • Humans and the Environment: Needs and Tradeoffs

NYS Science Standards - Key Ideas

  • LE Key Idea 1

    • Living things are both similar to and different from each other and from nonliving things.
  • LE Key Idea 5

    • Organisms maintain a dynamic equilibrium that sustains life.
  • LE Key Idea 6

    • Plants and animals depend on each other and their physical environment.
  • LE Key Idea 7

    • Human decisions and activities have had a profound impact on the physical and living environment
  • PS Key Idea 2

    • Many of the phenomena that we observe on Earth involve interactions among components of air, water, and land.
  • PS Key Idea 4

    • Energy exists in many forms, and when these forms change energy is conserved.

NYS Science Standards - Major Understandings

    • Matter is transferred from one organism to another and between organisms and their physical environment. Water, nitrogen, carbon dioxide, and oxygen are examples of substances cycled between the living and nonliving environment.
    • The environment may contain dangerous levels of substances (pollutants) that are harmful to organisms. Therefore, the good health of environments and individuals requires the monitoring of soil, air, and water, and taking steps to keep them safe.

NYS Science Standards - MST

    • Students will apply technological knowledge and skills to design, construct, use, and evaluate products and systems to satisfy human and environmental needs.
    • Students will apply the knowledge and thinking skills of mathematics, science, and technology to address real-life problems and make informed decisions.