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Science is a Never-Ending Process



Age Level
Grades 6-12

One of the scientific terms most commonly misunderstood by the public is the word theory. By investigating one of two prominently supported theories — germ theory or plate tectonics — students will understand how these theories have changed over time while still maintaining their scientific rigor and relevance. Additionally, by participating in a historical case study, students will discard the common misconception of a systematic scientific method as the only blueprint for achieving discovery.

NGSS Standards

DCIs (Disciplinary Core Ideas)
Nature of Science:
Middle School Level
  1. MS-ETS1.A1: The more precisely a design task’s criteria and constraints can be defined, the more likely it is that the designed solution will be successful. Specification of constraints includes consideration of scientific principles and other irrelevant knowledge that are likely to limit possible solutions.
  2. MS-ETS1.B2: There are systematic processes for evaluating solutions with respect to how well they meet the criteria and constraints of a problem.
  3. MS-ETS1.B3: Sometimes parts of different solutions can be combined to create a solution that is better than any of its predecessors.
  4. MS-ETS1.C1: Although one design may not perform the best across all the tests, identifying the characteristics of the design that performed the best in each test can provide useful information for the redesign process — that is, some of those characteristics may be incorporated into the new design.
High School Level
  1. HS-ETS1.A1: Criteria and constraints also include satisfying any requirements set by society, such as taking issues of risk mitigation into account, and they should be quantified to the extent possible and stated in such a way that one can tell if a given design meets them.
  2. HS-ETS1.B1: When evaluating solutions, it is important to take into account a range of constraints, including cost, safety, reliability, and aesthetics, and to consider social, cultural, and environmental impacts.
Epidemiology Storyline:
Middle School Level
  1. MS-LS4.B1: Natural selection leads to the predominance of certain traits in a population, and the suppression of others.
  2. MS-LS4.B2: In artificial selection, humans have the capacity to influence certain characteristics of organisms by selective breeding. One can choose desired parental traits determined by genes, which are then passed on to offspring.
  3. MS-LS4.C1: Adaptation by natural selection acting over generations is one important process by which species change over time in response to changes in environmental conditions. Traits that support successful survival and reproduction in the new environment become more common; those that do not become less common. Thus, the distribution of traits in a population changes.
High School Level
  1. HS-LS4.B1: Natural selection occurs only if there is both (1) variation in the genetic information between organisms in a population and (2) variation in the expression of that genetic information — that is, trait variation — that leads to differences in performance among individuals.
  2. HS-LS4.B2: The traits that positively affect survival are more likely to be reproduced, and thus are more common in the population.
  3. HS-LS4.C1: Evolution is a consequence of the interaction of four factors: (1) the potential for a species to increase in number (2) the genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for an environment’s limited supply of the resources that individuals need in order to survive and reproduce, and (4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment.
  4. HS-LS4.C2: Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically, behaviorally, and physiologically well suited to survive and reproduce in a specific environment. That is, the differential survival and reproduction of organisms in a population that have an advantageous heritable trait leads to an increase in the proportion of individuals in future generations that have the trait and to a decrease in the proportion of individuals that do not.
  5. HS.LS4.C3: Adaptation also means that the distribution of traits in a population can change when conditions change.
Plate Tectonics Storyline:
Middle School Level
  1. MS-ESS1.C2: Tectonic processes continually generate new ocean sea floor at ridges and destroy old sea floor at trenches.
  2. MS-ESS2.B1: Maps of ancient land and water patterns, based on investigations of rocks and fossils, make clear how Earth’s plates have moved great distances, collided, and spread apart.
High School Level
  1. HS-ESS1.C1: Continental rocks, which can be older than 4 billion years, are generally much older than the rocks of the ocean floor, which are less than 200 million years old.
  2. HS-ESS2.A1: Earth’s systems, being dynamic and interacting, cause feedback effects that can increase or decrease the original changes.
  3. HS-ESS2.A2: Evidence from deep probes and seismic waves, reconstructions of historical changes in Earth’s surface and its magnetic field, and an understanding of physical and chemical processes lead to a model of Earth with a hot but solid inner core, a liquid outer core, a solid mantle and crust. Motions of the mantle and its plates occur primarily through thermal convection, which involves the cycling of matter due to the outward flow of energy from earth’s interior and gravitational movement of denser materials towards the interior.
  4. HS-ESS2.B1: The radioactive decay of unstable isotopes continually generates new energy within Earth’s crust and mantle, providing the primary source of the heat that drives mantle convection. Plate tectonics can be viewed as the surface expression of mantle convection.
  5. HS-ESS2.B2: Plate tectonics is the unifying theory that explains the past and current movements of the rocks at Earth’s surface and provides a framework for understanding its geologic history. Plate movements are responsible for most continental and ocean floor features and for the distribution of most rocks and minerals within Earth’s crust.
  6. HS-ESS2.E1: The many dynamic and delicate feedbacks between the biosphere and other Earth systems cause a continual coevolution of Earth’s surface and the life that exists on it.
Performance Expectations
Nature of Science:
Middle School Level
  1. MS-ETS1-1: Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
  2. MS-ETS1-2: Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
  3. MS-ETS1-3: Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
High School Level
  1. HS-LS2-1: Use mathematical and/or computational representations to support explanations of factors that affect carrying capacity of ecosystems at different scales.
  2. HS-ETS-1-1: Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
  3. HS-ETS-1-3: Evaluate a solution to a complex real-world problem based on prioritized criteria and trade-offs that account for a range of constraints, including cost, safety, reliability, and aesthetics as well as possible social, cultural, and environmental impacts.
Epidemiology Storyline:
Middle School Level
  1. MS-LS4-4: Construct an explanation based on evidence that describes how genetic variations of traits in a population increase some individuals’ probability of surviving and reproducing in a specific environment.
  2. MS-LS4-5: Gather and synthesize information about technologies that have changed the way humans influence the inheritance of desired traits in organisms.
  3. MS-LS4-6: Use mathematical representations to support explanations of how natural selection may lead to increases and decreases of specific traits in populations over time.
High School Level
  1. HS-LS4-2: Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and produce in the environment.
  2. HS-LS4-3: Apply concepts of statistics and probability to support explanations that organisms with advantageous heritable trait tend to increase in proportion to organisms lacking this trait.
Plate Tectonics Storyline:
Middle School Level
  1. MS-ESS2-2: Construct an explanation based on evidence for how geoscience processes have changed Earth's surface at varying time and spatial scales.
  2. MS-ESS2-3: Analyze and interpret data on the distribution of fossils and rocks, continental shapes, and seafloor structures to provide evidence of the past plate motions.
High School Level
  1. 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.
  2. 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.
  3. HS-ESS2-3: Develop a model based on evidence of Earth’s interior to describe the cycling of matter by thermal convection.
  4. HS-ESS2-7: Construct an argument based on evidence about the simultaneous coevolution of Earth’s systems and life on Earth.
Other Relevant NGSS References
  1. NGSS Appendix F: Science and Engineering Practices in the NGSS
  2. NGSS Appendix G: Crosscutting Concepts
  3. NGSS Appendix H: Understanding the Scientific Enterprise: The Nature of Science in the Next Generation Science Standards
  4. NGSS Appendix J: Science, Technology, Society and the Environment

Note: Due to the nature of this entire unit, these four appendices are a vital component of why these activities are important in the science classroom. While a wide variety of science topics are selected to demonstrate the nature of science, all five mini-unit lesson sets incorporate the ideals of these four appendices and provide numerous opportunities for the application of scientific knowledge across a variety of disciplines.

This is a beta version of Lesson Two.

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