A novel way to learn about science content and the practice of modeling.

Transcription

1 A novel way to learn about science content and the practice of modeling. Lauren Barth-Cohen and Edwing Medina October

2 Important science phenomena such as atomic structure, evolution, and climate change are often hard to observe directly. That s why an important scientific practice is to use scientific models to represent one s current understanding of a system. Using models has been included as an essential science and engineering practice in the Next Generation Science Standards (NGSS Lead States 2013). This article describes an instructional unit that uses an iterative process of generating, critiquing, and revising complex scientific models that address sea level rise. Modeling sea level rise Climatology models are not easily accessible to most high school students, who have limited computer programming and mathematical modeling experience. Yet, climate change is a timely and important topic of interest to the general public, students, and teachers. We wanted students final models to approximate those of professional scientists. In climatology, an Aqua Planet is a scientific model commonly used to investigate large-scale patterns (Hess, Battisti, and Rasch 1993; Neale and Hoskins 2000). The Aqua Planet represents a hypothetical ocean-covered globe with which one can straightforwardly reason about global-level climate patterns such as ocean currents. Although climatologists typically use a computational Aqua Planet, we worked with a conceptual version that was a two-dimensional drawing. Our instructional unit (Figure 1) focused on sea level rise as a consequence of climate change. It involved approximately 10 hours of instruction and was built around a few core physics and Earth science concepts (e.g., convection currents) that are widely applicable beyond climatology (see On the web for the lesson plans). The unit is appropriate for an advanced Earth science course or an elective environmental science class, or perhaps as an end-of-year unit in a physics class. We implemented this unit in a weeklong summer professional development (PD) workshop for seventh- to 12thgrade physical science teachers. The unit aligns with the NGSS (see box, p. 36). Central to the instruction was using a series of increasingly complex models to reason about factors influencing sea level. Principal among these was temperature, thermal expansion, and melting ice, which influence each other through feedback mechanisms (model examples, Figure 2). Before participants made the initial model, we used laboratory activities to illustrate convection currents and the Coriolis effect (the apparent deflection of moving objects to the right in the Northern Hemisphere and to the left in the Southern Hemisphere due to the rotation of the Earth). These were then used in the initial Aqua Planet model to reason about ocean currents. The second model added dry land (a small increase in complexity), allowing for reasoning about the effects of that land on ocean currents and sea level. Between the second and third model, we did an albedo laboratory activity (albedo is a measure of brightness, that is, how much solar radiation is reflected). The third model added ice and increased complexity by needing to account for how the different albedo of the land and ice would affect temperature and sea level. In this model, FIGURE 1 Overview of the sea level rise unit. Framing Question: What factors influence sea level? Physics Concepts: Coriolis Effect, convection currents, albedo Lab activities to investigate core physics concepts (Coriolis effect and convection currents). Model 1: Aqua Planet: 2D model of a planet with no land and no ice. Model 2: Add land to the Aqua Planet model. How does the temperature change? How does that influence sea level? Lab activity to investigate albedo. Model 3: Add ice to the model. How does temperature change? How does that influence sea level? Model 4: Realistic planet. What factors influence sea level? Model 5: Future planet. What happens if temperature increases by one, three, and five degrees? How does the sea level change? Model 6: Global vs. local sea level factors. Exploring tides, wind, currents, land elevation, and local rainfall using online NOAA data sets and GIS tools. Which locations experience the greatest sea level rise? What factors are most important? How does it vary across the U.S. East, West, and Alaskan coasts? Final discussion: What factors will lead to an increase in sea level? Instructional sequence 34 The Science Teacher

3 Using Models to Understand Sea Level Rise FIGURE 2 Progression of models from the sea level rise unit. Aqua planet. Aqua planet plus land. Aqua planet plus land and ice. Realistic planet (upper left) and future planets. as ice melts, the resulting additional surface area becomes either dry land or open water, both of which absorb more solar energy than ice. This process causes an increase in the Earth s temperature, which in turn, causes more melting in a positive feedback loop. When adding land or ice to these models, instructions about amount and location were kept deliberately general, ensuring differences among the group s models. The fourth model was a realistic Earth with all seven continents and ice at both poles, where currents become even more complicated. The fifth model involved hypothetically raising the Earth s temperature one, three, and five degrees Celsius to examine how the currents, and in turn sea level, would change as a result. Afterward, we generated the sixth and final model using a jigsaw activity (an instructional technique where small groups build expertise from a larger knowledge base then reassemble into different groups and share that expertise to complete a task that relies on everyone). For this activity, small groups were instructed to pick three locations on the U.S. shoreline along the East, West, and Alaskan coasts. Within each group, one person was assigned to consider one of five factors (tides, currents, winds, land elevation, and rainfall and runoff) that potentially influence local sea level at each location. Using scientific data sets available online from the National Oceanic and Atmospheric Administration (NOAA) and other online resources (see On the web ), the groups researched their factor s data at each of their three chosen October

4 Connecting to the Next Generation Science Standards (NGSS Lead States 2013). Standards HS-ESS2 Earth s Systems HS-ESS3 Earth and Human Activity Performance Expectations The chart below makes one set of connections between the instruction outlined in this article and the NGSS. Other valid connections are likely; however, space restrictions prevent us from listing all possibilities. The activities outlined in this article are just one step toward reaching the performance expectations listed below. HS-ESS2-4. Use a model to describe how variations in the flow of energy into and out of Earth s systems result in changes in climate. HS-ESS3-1. Construct an explanation based on evidence for how the availability of natural resources, occurrence of natural hazards, and changes in climate have influenced human activity. MS-ESS2-6. Develop and use a model to describe how unequal heating and rotation of the Earth cause patterns of atmospheric and oceanic circulation that determine regional climates. Specific connections to classroom Dimension Name and NGSS code/citation activity Science and Engineering Practices Disciplinary Core Ideas Developing and Using Models Use a model to provide mechanistic accounts of phenomena. (HS-ESS2-4). Constructing Explanations and Designing Solutions Construct an explanation based on valid and reliable evidence obtained from a variety of sources. (HS- ESS3-1). ESS2.A: Earth Materials and Systems Changes to... climate can be caused by interactions among changes in the Sun s energy output or Earth s orbit, tectonic events, ocean circulation, volcanic activity, glaciers, vegetation, and human activities. (HS-ESS2-4) ESS2.C: The Roles of Water in Earth s Surface Processes. The complex patterns of the changes and the movement of water in the atmosphere, determined by winds, landforms, and ocean temperatures and currents, are major determinants of local weather patterns). Students generate, present, and discuss a series of increasingly complex models for the factors that impact sea level rise. Students compare each model with prior ones while discussing the assumptions and limitations of that model. The final models are used to construct an explanation for the factors affecting sea level rise. Student models show how the Coriolis effect, ocean currents, and albedo impact sea level. The jigsaw activity shows how changes in tides, currents, wind, land elevation, and rainfall and runoff impact local sea levels at different locations. Crosscutting Concepts Cause and Effect Empirical evidence is required to differentiate between cause and correlation. (HS-ESS2-4), (HS-ESS3-1). Stability and Change Feedback (negative or positive) can stabilize or destabilize a system. Student models show how the Coriolis effect, thermal expansion, and changes to the relative albedo can affect changes to the Earth s temperature and sea level. The jigsaw activity shows how tides, currents, wind, land elevation, and rainfall and runoff affect local sea levels at different locations. 36 The Science Teacher

5 Using Models to Understand Sea Level Rise This unit on sea level rise is a good example of how to teach important and less frequently covered topics in a manner that aligns with the NGSS (see box). We found that teachers and their students generally had a positive experience with this conceptual modeling approach. Finally, we note that for English language learners, this conceptual modeling approach provides visual supports that can aid in and increase the use of language (Moschkovich 2012). locations to examine whether the factor might lead to an increase or a decrease in sea level in a warming climate. This activity was challenging. Because the factors operate at various time scales (e.g., diurnal and seasonal, long and short term) and at different locations, various factors could have a stronger or weaker effect. For instance, many participants contrasted the dramatic effect of the uplift of land in Alaska (due to tectonic motions and the removal of ice load from melting glaciers; see On the web, ) to the sinking of land in New Orleans (due to a combination of natural geologic and human-induced processes; see On the web ). Finally, the small groups incorporated their research into their models, adding a further level of complexity and relevance. As the small groups worked, we held formative assessment gallery walks to observe, compare, and discuss peers models, including their differences and similarities in how they explained the phenomena. Summative assessment might involve showing students models similar to the ones they had created and asking them to reason with the model; for example, to make predictions about sea level rise in various locations. Some participants initially assumed that sea level rise is akin to stepping into a bathtub, raising the water level equally around the rim. However, sea level rise is not felt uniformly across the globe. As illustrated in the jigsaw activity, local factors can have dramatic effects, an important takeaway from this unit. Conclusion Data analysis from pre- and post-pd surveys along with exit interviews suggest that this approach was effective in teaching about the learning benefits of scientific modeling while also addressing the science of sea level rise in different regions. These conceptual modeling units were focused on these topics but could be widened to address the role of human activities in influencing sea level rise and climate change more broadly. When implementing this approach in other topic areas, we suggest starting with a few foundational science concepts, such as mechanisms of energy transfer, and then using those concepts repeatedly within both simple and complex models. Lauren Barth-Cohen (Lauren.BarthCohen@Utah.edu) is an assistant professor of science education at the University of Utah in Salt Lake City, and Edwing Medina is a doctoral student in STEM education at the University of Miami in Coral Gables, Florida. Acknowledgments We are grateful to all the teachers and students who participated in this project. Thanks to Kim Chamales for helping design the instruction and teach the course. This work was supported by a donation to the University of Miami, School of Education and Human Development. On the web Alaska sea level: New Orleans sinking: Wind and land elevation: Wind: Ocean surface currents: Ocean surface currents: Rainfall and runoff: Rainfall and runoff: Sea level rise and flooding effects: Sea level rise and flooding effects: digitalcoast/tools/slr References Hess, P.G., D.S. Battisti, and P.J. Rasch Maintenance of the intertropical convergence zones and the large-scale tropical circulation on a water-covered earth. Journal of the Atmospheric Sciences 50 (5): Moschkovich, J Mathematics, the Common Core, and language: Recommendations for mathematics instruction for ELs aligned with the Common Core. Commissioned papers on Language and Literacy Issues in the Common Core State Standards and Next Generation Science Standards, pp Proceedings of Understanding Language Conference. Palo Alto, CA: Stanford University. Neale, R.B., and B.J. Hoskins A standard test for AGCMs including their physical parametrizations: I: The proposal. Atmospheric Science Letters 1 (2): NGSS Lead States Next Generation Science Standards: For states, by states. Washington, DC: National Academies Press. October