APPENDIX: Instructor’s Guide
• Fill a common bowl (or multiple bowls, if more convenient for classroom setup) with water.
• Place pennies in bowl(s) of water. Make sure there are enough pennies for each student using the bowl to have one.
• Give each student one cup, each labeled with the name of an organism in a local food web (copepod, mummichog, or
striped bass in our example). Thus, each student represents an organism in that food web. (The instructor can hold onto
the large “human” cup.)
Procedure Details: Instructions For Instructors And Students
Discussion prompts are printed in italics.
Ingesting Pollutants (~5 minutes)
What do organisms need to survive?
• Students should eventually provide the answer water.
• Students use the bowl(s) of water to fill their cups roughly halfway with water.
What do you think will happen when these organisms live in and drink from a polluted water source?
• Students should identify that the organisms will have pollution in them as well.
• Instructor drops one penny into each student’s cup to represent the methylmercury that they have ingested.
• It may help to explain that each penny represents a relatively small amount of methylmercury—not enough to cause any
negative health effects for the organisms. This clarification should prevent students from panicking that their organisms are
dying of mercury poisoning.
Ingesting Plant Material (~5 minutes)
Other than water, what do organisms need to survive?
• Students should eventually provide the answer food.
What do zooplankton and copepods eat? What do mummichogs eat? What do striped bass eat?
• Students may not be familiar with these organisms, so it may help to explain that zooplankton and copepods are herbivores, mummichogs are omnivores, and striped bass are carnivores. The food chain graphic (Figure 1) may also help familiarize students with their organisms.
• Zooplankton and copepods eat algae and phytoplankton (microscopic aquatic plants).
• Mummichogs eat both plant and animal material (e.g., algae, plants, zooplankton, copepods, insects, insect larvae, worms,
and small crustaceans, mollusks, and fish).
• Striped bass eat smaller fish (e.g., mummichogs), as well as eels, crabs, mollusks, and other aquatic animals.
• Instructor places a few cereal pieces into the cups of each student holding a zooplankton, copepod, or mummichog cup.
This cereal represents the algae that these organisms have consumed.
Simulating Bioaccumulation (~5 minutes)
The zooplankton and copepods are almost full of food and water. What organisms do when they are full?
• Students should identify that organisms excrete waste.
• Students with zooplankton and copepod cups “excrete waste” by carefully pouring some of the contents of their cups back
into the bowl(s) of water.
Do you get rid of all the water in your bodies when you go to the bathroom?
• The zooplankton and copepods also shouldn’t lose all of their water when they excrete waste.
• Emptying the cups only partway allows the pennies to remain in the cups, while water and cereal are lost.
• Students observe the zooplankton and copepod cups and record their observations (Observation Worksheet).
• Students should observe that the methylmercury remains in the zooplankton and copepods, even when regular food and
water are excreted.