Biomagnification and bald eagles

In this activity, students will study biomagnification by using paper cutouts to represent food containing chemicals eaten by fish. The students will then repeat this activity but as an eagle collecting fish. The amount of chemicals taken in by each eagle will then be compared to amounts taken in by each fish.

A lesson plan for grade 6 Science

By Elizabeth Caveny, Janet Carson, Heather Subleski, and Jeannie Galluzzo

Learn more

• Gould Education activities on foodwebs
• Carolina Raptor Center Located in Charlotte, the CRC has an eagle program as well as other programs available that teach about biomagnification and the effect of pollutants on birds of prey

Related pages

• Outer Banks Center for Wildlife Education: Students will learn the importance of North Carolina's wildlife resources at this environmental education facility.
• Tanglewood Park Nature Education Center: In spring and fall, Tanglewood Park offers quality nature education programs which are correlated with the N.C. Standard Course of Study for Science or Social Studies.
• Jockey's Ridge State Park: Experience a world of the shifting sands and a barren, desert environment as well as an estuarine environment of the tidal waters of the Roanoke Sound at Jockey's Ridge State Park in Nags Head, North Carolina.

Related topics

• Learn more about animals, biomagnification, birds of prey, eagles, ecosystems, environmental science, fish, food webs, and science.

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Learning outcomes

The students will enhance their understanding of biomagnification and will see the effects of contaminant flow through the food web.

Teacher planning

Time required for lesson

1 hour

Materials/resources

• strips of green colored paper to represent aquatic plants (any size, 4–5 per student)
• strips of orange colored paper to represent fish (2 per student)
• 3–5 strips of brown colored paper to represent eagles
• masking tape
• markers or crayons for each student

Pre-activities

• Review food webs. Most textbooks as well as the Project WILD materials and the Gould Education websitehave suggestions for activities that teach and review food webs.
• Introduce the concept of biomagnification.

Activities

1. Post a key at the front of the room identifying what each color strip represents: green for aquatic plants, orange for fish, and brown for eagles.
2. Give each student four or five of the strips of paper representing aquatic plants. Using markers or crayons have the student place two colored dots on one strip, three dots on the next strip, four dots on the next strip and five dots on another strip. The optional fifth strip may be left plain or have one dot put on it. Explain that these dots represent chemicals that have been taken into the plants from pollution in the water.
3. Collect all of the strips then scatter them about the room. Do not let the students watch you do this.
4. Tell the students that they are going to be fish eating the plants, then give them about fifteen to twenty seconds to go out and collect as much food as they can.
5. When students have returned to their seats, have them count the number of dots their fish “ate” and put the total number of dots onto a new colored strip to represent their fish (this paper was given to the students in the beginning). Have them also make another fish with the same number of dots as the first. Set this second set of fish to the side for use in step seven.
6. Draw a number line on the bottom of the board and label numbers covering the range of dots the fish took in. Each student can then tape one of his/her fish above the appropriate number, making an effective pictograph or line plot of the results. Discuss what information can be obtained from the graph and determine the mean, mode, median, and range of the graphed data. Discuss what each of these terms means and how it might be important.
7. Take up the second fish from each student and scatter them about the room as was done with the “plants.”
8. Pick three to five students to now act out the part of eagles eating from your “river.” Give the students fifteen to twenty seconds to collect as many fish as they can.
9. Repeat step six using the brown colored strips to represent eagles.
10. Compare the amount of chemicals taken in by the fish with the amount of chemicals taken in by the eagles.

Assessment

Take up all of the “fish” strips and all of the “eagle” strips. Divide the students into two or three smaller groups. Next, randomly distribute the fish strips then the eagle strips to the groups. Have students make their own pictographs from the data collected, then write their own definition of biomagnification.

Teachers tell your students the following:

• You should be able to draw the pictograph using a key that shows a fish and eagle standing for a particular amount (i.e., one fish is equal to two dots).
• You need to correctly show the numbers of dots the fish and the eagles had.
• You will need to give a brief definition, in your own words, of what biomagnification is (A sample student definition might be: when chemicals like DDT get into rivers and other bodies of water and build up into plants that animals eat. Those chemicals build up in the animals as they move through the food chain).

Supplemental information

Comments

Extension Activities:

1. If you have more time, the effects of biomagnification can be made clearer by adding an additional tropic level (ie. medium fish eating small fish, insects eating plants or fish eating insects).
2. A further math extension would be to figure the contaminate level of fish and of eagles as percent of weight. Students may research average bald eagle weights and average weight of fish caught, or you may use ten pounds as the average eagle weight and 1¹/₂ pounds for each fish weight.
3. For younger students or students who need more movement or just want to have more fun, put limitations on the way the students can move. For example, fish must walk using a shuffling step and must say “bubble, bubble” before they pick up their piece of food. Eagles must flap their wings (arms) as they move and must say “fish” before they pick up their food.
4. Use the graphs to discuss the meaning of a mean and how sensitive the mean is to extremes in the data.

This lesson plan was designed as a pre-visit activity for a sixth grade field trip to Carolina Raptor Center. It was created for the Science Museum Inquiry Project in collaboration with the Grassroots Science Museums Collaborative, the Carolina Raptor Center, and LEARN NC. It can, however, be used as a stand-alone activity for any group studying biomagnification.