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Exploring the Color of Coral Using a Primary Source

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This post was written by Lesley Anderson, 2021-2022 Albert Einstein Distinguished Educator Fellow at the Library of Congress.

Primary sources can be a wonderful opportunity to contextualize an anchoring phenomenon in the science classroom. Showing students this primary source can spark a great conversation in the classroom. Ask students to share what they observe in the picture with a neighbor. Encourage them to reflect on what they think might be happening in this picture, and record their questions and share with the class.

Students may identify that they are looking at corals and they may question whether these corals have any color. Students may also wonder why the divers have removed the coral from the ocean. The caption, “Coral Divers with their Wealth,” also implies that there may be economic gain associated with the extraction of the corals from the ocean. Ask students what they think this means in context with the primary source.

Image of men surrounded by coral.
Coral Divers with their Wealth, on the Great Barrier Reef, Australia, 1921

This primary source can be used to introduce the concept of human impacts on coral reef ecosystems. Encourage students to think about why the divers might have chosen to collect the corals and then make predictions about the impacts that this effort might have had on that ecosystem. This is a great opportunity to discuss how actions that might have been acceptable in the past can have a significant impact on the future.

Teachers working with this primary source can introduce their students to another indirect human impact on coral reef ecosystems, coral bleaching. Discuss how the symbiotic relationship between corals and zooxanthellae is impacted when events like ocean acidification or rapidly changing ocean temperatures occur in coral reefs. This anchoring phenomenon, including a demonstration and a contextualizing primary source analysis, can help students understand that coral bleaching does not occur from sunlight damage, but instead the changing ecosystem can put a strain on the symbiosis and affect the coral reef health while it is vulnerable.

Demonstrate to students by placing colorful candies with a hard shell in a circle on the outside ring on a white plate, covering the candy with warm water, and asking students to observe what happens when the warm water reaches the candy. The color eventually leaves the candy, leaving a white shell, much like the zooxanthellae leave the coral. Using this demonstration to reinforce the impact of climate on ecosystems can help solidify this phenomenon for students.

Connecting again to the primary source, students may wonder how humans and the changing climate have contributed to the current state of our coral reef ecosystems today. Students can research the different ways in which governments work to prevent overfishing and removal of living organisms from their natural habitats. How might students design a solution to minimize the human impacts on coral reef ecosystems to prevent them from being eliminated entirely in the near future?

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