Mercury Levels are Rising!

Lesson Content

• Lesson Plan Template:

  General Lesson Plan

• Learning Objectives: What should students know and be able to do as a result of this lesson?

  
  
  • Describe the research conducted by scientists on mercury levels in the oceans and the significance of their findings.
  • Explain how human activities have impacted mercury levels and why this concerns scientists.
  • Cite specific and relevant text evidence to support analysis of a text.
  • Use vocabulary strategies to determine the meaning of unknown academic and domain-specific words in a text.
  • Determine the central ideas of a text.
  • Construct a written response that clearly establishes the main point(s), contains relevant textual evidence to support the main point, utilizes transitions to maintain flow, effectively uses domain-specific vocabulary, and provides an appropriate conclusion.

   

• Prior Knowledge: What prior knowledge should students have for this lesson?

  
  

  In regards to science:

  • General familiarity with mercury poisoning would be beneficial to students. This site offers a brief and simple overview.
    • This five-minute video titled "The Effects of Mercury on the Brain" (uploaded by YouTube user GoodFightUK) describes the specific effects of mercury on the brain.
    • This article from Scientific American, titled "What is Mercury Poisoning?",describes the specifics of mercury poisoning.
  • Students should also have a basic understanding of biological magnification, as well as how these interactions can be shaped by ecological factors such as habitat loss and fragmentation.
    • This student-created video titled "Biomagnification" (2:39, uploaded by YouTube user TheQueenknn) covers biological magnification and might be useful for review.
    • This short video titled "Bioaccumulation and Biomagnification Animation" (1:22, uploaded by YouTube user Video Chat-one) illustrates bioaccumulation and biological magnification.
    • NOAA's biomagnification online activity is short, and it offers a great interactive way for students to review how biomagnification works.
  • Students should also have general knowledge of ecosystems and food webs.
    • This is a great 3-minute video by TedEd titled "Dead Stuff: The Secret Ingredient in Our Food Chain - John C. Moore" that discusses the flow of energy through an ecosystem.
    • This TedEd resource titled "The Secret Life of Plankton" (CPALMS Resource ID 117792) is a beautiful 6-minute video illustrating a marine ecosystem. This will allow the students to better understand the trophic levels in a marine ecosystem, which is where one would find tuna or orange roughy (these are referenced in the main article for this lesson).

  In regards to literacy skills:

  • Students should have prior experience utilizing various vocabulary strategies to determine the meaning of unknown words in a text. For this lesson, it would be helpful if students had prior experience using context clues, word parts, and dictionary skills to determine the meaning of unknown words.
  • Students should understand the term "central idea" and be able to distinguish central ideas from key details.
  • "Central idea" means the same thing as "main idea." The central idea is the author's main point about the topic or topics in a text. The central ideas are the dominant, most important, or chief ideas that emerge from all the ideas presented in a text. Students should be aware that the author can have several main points he or she wants to make about the topic or topics in a piece of writing, and as a result, there can be multiple central ideas in a text, especially in longer more complex pieces.
  • Key, or in other words, important, details in a text help an author support and develop his or her central ideas.
  • Students should be aware of text features that can help them locate and learn information when reading a text. The text features in the NSF article include a title, subtitle, photographs, and captions.
  • Based on the writing rubric provided with this lesson, students should be able to respond to a writing prompt in a clear, organized manner that includes use of an introduction to establish the main point(s), a body paragraph(s) that support the main point(s) and includes relevant and specific textual evidence, and a conclusion that supports the main point(s).
  • Students should have some awareness that use of transition words or phrases can help a piece of writing flow smoothly from one point or idea to the next. This site provides transitions teachers might provide to help students utilize transitions in their writing.

   

• Guiding Questions: What are the guiding questions for this lesson?

  
  
  1. Why is there a need to determine the amount of mercury in the oceans?

     Mercury is a neurological poison. It is both naturally occurring and formed as a by-product from human activity. Mercury does not breakdown in humans and is stored in our tissues. Over time it causes neurological damage and even death. Fish and aquatic organisms can be high sources of mercury.

  2. Why is it important for scientists to be able to determine the amount of mercury that is naturally occurring versus that which is occurring due to human activity?

     Scientists need to be able to determine the amount of mercury produced by human activity to aide in their predictions of mercury levels in the future and to serve as evidence that can be used to argue for the importance of regulating mercury pollution. The first global measurements of mercury levels show that mercury levels in shallow water have increased three times since the Industrial Revolution. We cannot continue to increase the concentrations of mercury in our environment and expect to have healthy ecosystems.

  3. What were scientists able to determine using phosphate and carbon dioxide?

     Phosphate behaves like mercury so scientists were able to use phosphate to estimate the amount of mercury in deeper water. Deeper water has not been exposed to the atmosphere since the Industrial Revolution. The mercury in those waters provides a baseline for how much mercury is released naturally.

     Carbon dioxide is one of the most well-studied gases of the past 40 years. Human-produced carbon dioxide comes from some of the same activities that produce mercury pollution. Scientists were able to measure the amounts of carbon dioxide in shallower waters, water that has been exposed to the atmosphere. Because of the link between mercury and carbon dioxide, scientists were able to estimate the amount of mercury that is produced by humans.

  4. Explain the significance of the scientists' findings. How have human activities impacted mercury levels and why does this concern scientists?

     Please see the text-dependent questions sample answer key. The writing prompt sample answer deals with these questions.

   

• Teaching Phase: How will the teacher present the concept or skill to students?

  
  
  1. Begin the lesson by posing a general question to the class: "What is mercury poisoning?"
     • Some students may be able to give general details about the effects of mercury poisoning. For example: vision problems, the feeling of pins and needles, lack of coordination, muscle weakness, impaired speech, impaired hearing and walking, tremors, headaches and twitching. Many students will know it can cause death.
  2. Next, ask the class this question: "Where does mercury come from?"
     • At least some students in the class should know that mercury is a naturally occurring element. A few students might speculate that it is also produced by humans. Few students will know that mercury is a byproduct of activities like burning coal and making cement. Students may also mention fish in reference to mercury.
  3. Next, ask students: "How does mercury become part of our bodies?"
     • Student answers will vary. The biggest source of mercury is consuming fish, other sources of mercury include dental fillings, jewelry, older thermometers and gold mining.
  4. End the discussion by informing students that we will be reading an article that addresses the problem of mercury in our environment and how scientists came up with a method to determine how much is produced by human activity.

   

• Guided Practice: What activities or exercises will the students complete with teacher guidance?

  
  
  1. Provide each student with a copy of the article "Mercury in the World's Oceans: On the Rise." For class discussions that will follow, it might be helpful to have students number each paragraph.
  2. Provide each student with a note-taking guide.
  3. Before students begin reading, direct them to pay attention to the text features of the article to help them learn and locate information:
     • Title: Mercury in the World's Oceans: On the Rise
     • Subtitle: New results show three times as much in upper oceans since Industrial Revolution times
     • Captions: Located under each photograph
  4. Students can read the text for the first time and then complete the vocabulary portion of the note-taking guide. Students will need access to print or online dictionaries. The teacher should monitor students as they work and provide support and guidance as needed. The note-taking guide is structured so that students will work to define their own unknown words. Teachers can modify this part of the guide by directly providing vocabulary that students will define. After students have defined their unknown vocabulary words, students can use these definitions to help them as they re-read the text. After re-reading the text, students can use the text to help them complete the remaining portions of the note-taking guide.

  Formative Assessment (How will teachers check for student understanding?):

  1. Teachers can check students' understanding by collecting students' completed note-taking guide, checking their work, providing written feedback, or grading the assignment. Or, teachers can have students share out their responses and the teacher can provide verbal corrective feedback, allowing students to make corrections to their work during the discussion.
  2. Teachers can use this sample answer key to help them assess students' answers.
  3. For discussion on students' answers to words they defined, teachers are encouraged to not only ask students to explain the meaning they determined for a word, but the strategy they used to arrive at that meaning. This will allow the teacher to provide alternative suggestions as to how the student could have arrived at the correct meaning of the word.

  Common errors/misconceptions to anticipate and how to respond:

  1. One common error is that mercury is still used in thermometers, but this is incorrect. The most common additive is alcohol.
  2. Students often use the 10% law to try to explain how contaminants move throughout an ecosystem. Mercury cannot be broken down in the body to be used as energy. Instead, it is stored in tissues and becomes more concentrated the higher we move up the food web.
  3. Students that don't eat fish often can push this off as "not their problem." They need to be reminded that all trophic levels are connected one way or the other and that all ecosystems are important.

   

• Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the lesson?

  
  

  Provide each student with a copy of the text-dependent questions to complete. Students should be reminded to continually refer back to the text and to use relevant and specific evidence from the text to support their answers.

  Formative Assessment (How will teachers check for understanding?):

  1. Teachers can check students' understanding by collecting students' answers to the text-dependent questions, checking their work, providing written feedback, and maybe grading the assignment. Or, teachers can have students share out their responses and the teacher can provide verbal corrective feedback, allowing students to make corrections to their work during the discussion.
  2. Teachers can use the sample answer key provided at the end of the text-dependent questions to help them assess students' answers.

  Common errors/misconceptions to anticipate and how to respond: Please see the text-dependent questions sample answer key.

   

• Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?

  
  
  1. Before students complete the writing prompt for the summative assessment be sure to review responses to the text-dependent questions as a class, including covering the misconceptions and key points described in the sample answer key.
  2. The following article should be read aloud together as a class. This article by Nature, titled "Humans Have Tripled Mercury Levels in Upper Ocean," provides more quantitative measurements on the amount of mercury produced by human activity, in addition to other details about the scientists' research on mercury levels, the significance of their findings, and the impact current mercury levels are having on people and marine life. This article should be read before students begin the summative assessment. The summative assessment will allow students to pull together the two articles in order to form a solid understanding of the mercury problem. After reading this second article, discuss the following questions as a class.
     • Why is the new analysis of the amount of mercury in the oceans better than the previous computer models?

     It fills in important pieces of information--where the mercury came from and how deep it is found in the ocean.

     • How have ocean circulation patterns helped to decrease the effects of the rise of marine mercury?

     The circulation patterns drive very cold and salty water into the deep ocean, carrying a lot of mercury from the shallower waters with it.

     • David Krabbenhoft states that the oceans are not uniformly contaminated. Why is that beneficial?

     This is beneficial because it shows that mercury levels are generational. If that is the case, there is real hope that if we make changes to decrease mercury pollution, that it really will be able to make a difference.

  3. After students' written responses for the summative assessment have been graded and returned with feedback, teachers might wish to use the provided sample response with the class. Students who are struggling writers can benefit greatly from seeing a well-organized, detailed written response. The teacher could show the sample response on an overhead or with an LCD projector and discuss some of the following.
     • Have students identify the main points in each body paragraph: an explanation on what mercury is and where it comes from, the purpose and description of the scientists' research, the scientists' findings, the current and future threats to health, hope for the future.
     • Have students identify accurate use of domain-specific vocabulary (e.g., element, environment, phosphorus, carbon dioxide, atmosphere, Industrial Revolution, pollution) and academic vocabulary (e.g., byproduct, detectable, regulation, tracer, compounds).
  4. Final closure: A great way to pull this lesson to a close is to have the students conduct some independent research and produce a public service announcement or poster to help educate people about the sources of mercury poisoning and fish they should avoid eating.

   

• Summative Assessment

  
  
  1. Students will individually respond to the writing prompt. They should be directed to respond with a multi-paragraph response, with a clear introduction, body section, and conclusion. They can refer back to the texts as they construct their response.
  2. Provide students with a copy of the rubric and go over the rubric with them so they will know how their written response will be assessed.
  3. Go over the writing prompt with students and make sure students understand what the prompt is asking them to address.

     The prompt: Using information from both texts in this lesson (the one from NSF and the one from Nature), describe the research conducted by scientists on mercury levels in the oceans, as well as the significance of their findings. How have human activities impacted mercury levels and why does this concern scientists?

  4. Teachers will use the rubric to assess students’ written responses.

   

• Formative Assessment

  
  

  Specific suggestions for conducting the Formative Assessment can be found in the Guided Practice and Independent Practice phases of the lesson.

   

• Feedback to Students

  
  

  Specific suggestions for providing Feedback to Students can be found in the Guided Practice and Independent Practice phases of the lesson where it says, "Common errors/misconceptions to anticipate and how to respond."