Claim-Evidence-Reasoning and the Wallace Line
Like most public high schools in California, my school district adopted the Next Generation Science Standards (NGSS) three-year model for high school, which means that all three “traditional” curricula of biology, chemistry, and physics now have the course-relevant Earth/space science performance expectations embedded.
For many teachers, this has been perceived as a significant challenge. I sympathize with those who struggle with what seems like an inclusion of more content to teach, as well as those who argue that “I’m neither a geologist nor an astrophysicist.” The key to success is in recognizing that, by bundling related life science and Earth science standards, teachers have an even richer opportunity to help their students uncover the reality that Earth and life evolve together.
Evolution is not only one of the four anchoring topics in the NGSS Life Science Standards, but it is also recognized as the underlying principle governing a true understanding of how life works. By expecting all students to achieve age-appropriate mastery of Earth and Space Science Standards, the NGSS provide both a challenge and an opportunity for teachers to help students understand that the story of life on planet Earth is one of coevolution of the planet and the life on it. By explicitly teaching examples of life and Earth’s coevolution, I strengthen my students’ understanding of biological evolution, both as a process and as a theory, as we explore many different lines of evidence for evolution together.
One of those lines of evidence is the field of biogeography. Biogeography allows my students and me to study the coevolution of life and Earth’s systems. An additional benefit of studying the simultaneous history of Earth and life is that it allows us to meet several of the NGSS Earth Sciences Performance Expectations (PEs) that are now embedded in many life science curricula. One of these PEs is HS-ESS2-7: “Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.”
I use the story of A.R. Wallace and his discoveries in the Malay Archipelago as a way to help my students accomplish the above goals. The following lesson not only provides students with an opportunity to achieve age-appropriate mastery of the Disciplinary Core Ideas specified by the “Natural Selection and Evolution” PEs, but it also simultaneously allows students to engage in another dimension of the PEs: the Science and Engineering Practices (SEPs). As the lesson progresses, students progress through a series of SEPs, including obtaining, evaluating, and communicating information; making and using models; and constructing explanations. The lesson culminates in an assessment piece in which students argue from evidence using the “claim-evidence-reasoning” (CER) pedagogical technique. They experience the authentic scientific process of supporting a claim with evidence and providing the underlying reasoning.
We begin our study of biogeography by viewing the BioInteractive video The Animated Life of A.R. Wallace. This film introduces my 9th grade biology students to both Wallace and the Malay Archipelago in an engaging, entertaining way. I tell my students that they are now going to become explorers, following in Wallace’s footsteps as they search for patterns in the data Wallace collected during his time in the archipelago.
Students use the faunal data provided in the “Discovering the Wallace Line” activity to create a faunal map of the archipelago (Student Handout, Part 1, Questions 1–3). When students are finished, we review their completed maps to find that they have a rough approximation of the Wallace Line. After that, they brainstorm possible reasons for the existence of this line (Student Handout, Part 1, Question 4). Students share suggestions and consider the following question: “What were Mr. Wallace’s ideas about the patterns he observed?”
To answer this question, we watch the BioInteractive short film The Origin of Species: The Making of a Theory from 17:46 on, focusing on Wallace’s work and noting that he made the claim that the line exists because landmasses surrounding the Malay Archipelago had moved over time. However, at the time, there was no geologic evidence to support Wallace’s claim.
Today, of course, we have such evidence! I now show my students the two supplemental animations linked on the “Discovering the Wallace Line” activity page. As instructed on the Student Handout (Questions 5 and 6), students use the evidence in these animations to support Mr. Wallace’s claim with modern evidence and provide the reasoning for their explanation. I collect the completed handouts for evaluation.
Engaging in Wallace’s story and walking in his footsteps (he was, after all, not so much older than my students when he set off on his adventures!) is a potent way to facilitate my students’ progression from being passive recipients of information (however interesting) to being actively engaged in making sense of the world around them. Critical/analytical thinking is a “muscle” that must be developed and exercised, and I find it very satisfying to see the growth in my students’ science literacy when I assess their CERs. This kind of assessment challenges students to demonstrate proficiency in all three NGSS dimensions: they must communicate core ideas in evolutionary biology (the Disciplinary Core Ideas), they must argue from evidence (a Science and Engineering Practice), and they must show insight into how Earth and life function together as a system (a Crosscutting Concept).
For educators who are using the 5E lesson model in their classrooms, it should be noted that this lesson follows the sequence of Engage, Explore, Elaborate, Explain, Evaluate. The progression is outlined below; a link to the full lesson plan follows.
Lesson Outline: Biogeography as Evidence for Evolution
Objective: Students will explore how biogeography provides evidence in support of the process of evolution.
NGSS Performance Expectations:
- HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
- HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.
- HS-ESS2-7. Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.
Conceptual connections to:
- HS-ESS1-5. Evaluate evidence of the past and current movements of continental and oceanic crust and the theory of plate tectonics to explain the ages of crustal rocks.
- HS-ESS2-1. Develop a model to illustrate how Earth’s internal and surface processes operate at different spatial and temporal scales to form continental and ocean-floor features.
NGSS Science and Engineering Practices:
- Obtaining, evaluating, and communicating information
- Making and using models
- Constructing explanations
- Arguing from evidence
ENGAGE/EXPLAIN: BioInteractive short video: The Animated Life of A.R. Wallace
EXPLORE: BioInteractive activity: “Discovering the Wallace Line”, Part 1, Questions 1–4
ELABORATE: BioInteractive short film: The Origin of Species: The Making of a Theory, plus discussion of the following question: “What was Wallace’s claim about the underlying cause of the Wallace Line?”
- Ask the following question: “Is there evidence that supports Wallace’s claim that the landmasses have changed over time?”
- Show the two supplemental animations linked on the “Discovering the Wallace Line” activity page.
- Have students complete Part 2 of the Student Handout (Questions 5 and 6) to support Wallace’s claim with modern evidence and provide the underlying reasoning for their explanation.
EVALUATE: Collect completed handout(s) for assessment.
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Nikki Chambers teaches Introductory Biology to 8th and 9th graders and Astrobiology to 12th graders in Torrance, California. She is a member of the NGSS Science Expert Panel with the California Department of Education. She loves sharing the wonder of knowing that all life is connected and that we are all made of stardust. During her nonteaching months, she is thrilled to do research on the effects of climate change on insects on this planet, as well as the possibility of relict life on our neighboring planet, Mars.
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